Progress 10/01/04 to 09/30/05
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Disease resistance in soybean to root rot caused by Phytophthora sojae and Fusarium solani f.sp. glycines (= F. virguliforme) must be improved and available to breeders to minimize yield losses. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. Research objectives and approaches in this project focus on a better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations to identify and describe more effective and efficient use of resistance in soybean production. With the identification of new races of P. sojae (>18 in the 1990s) and increased inoculum potential for root rot by both P.
sojae and F. solani in soybean production fields, it is important to identify new and improved sources of resistance and to continue documenting distribution and frequency of races and strains to maximize disease control strategies. Soybean is the major oilseed crop in the world with an annual value of nearly 14 billion dollars in the U.S. Cultivars and germplasm with improved chemical composition and yield potential must have resistance to major pathogens to make production profitable. This project will focus on root rot diseases caused by Phytophthora sojae (Phytophthora root rot) and Fusarium solani f. sp. glycines (sudden death syndrome). Yield losses attributed to soybean diseases exceed 14% annually. However, Phytophthora root rot has the potential to cause much higher yield losses if resistance is not regularly incorporated into enhanced germplasm. The Rps1-k gene is currently a widely used form of resistance incorporated in cultivars, but it is not effective against race 25
and several new races identified in Indiana and Ohio during the 1990s. Recent reports by NCR- 137 and North Central Soybean Research Program (NCSRP) committees indicate that more information is needed about population dynamics of P. sojae races and about host/pathogen interactions in sudden death syndrome (SDS). Losses from SDS, a relatively new root rot disease caused by a toxin-producing strain of F. solani, are not well documented but have increased dramatically in the 1990s. Initially, SDS damage was more extensive in river floodplain areas, but now it poses a serious threat to soybeans throughout the Midwest. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. A better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations is needed and should lead to a more
effective and efficient use of resistance in soybean production. How serious is the problem? Why does it matter? Prior to the 1990s, races of Phytophthora sojae were controlled by growing soybeans with the Rps1-k gene and little is known about resistance and epidemiology of SDS caused by Fusarium solani f. sp. glycines, which is a relatively new disease of soybeans. Pathology research efforts are underway to verify the current race situation and population dynamics of P. sojae and F. solani f. sp. glycines common to Indiana soybean production fields. Representative races maintained for pathology and breeding efforts are being utilized to incorporate additional Rps genes (gene combinations and the recently identified Rps8 gene) into elite soybean breeding lines to provide improved Phytophthora resistance. Yield reductions due to Phytophthora are estimated at $124,000,000 per year for the U.S. in the 1990s. Managing Phytophthora with genetic resistance currently available would
provide full season disease control and result in significant economic benefit and reduce the need for fungicide treatment that only provides partial or temporary control. Yield reductions due to sudden death syndrome (SDS) are similar to that listed above for Phytophthora and they continue to increase throughout the Midwest states. Almost all soybean varieties are highly susceptible to SDS and yield losses in Indiana were common in central as well as southwest Indiana in recent years. Identification and incorporation of genetic resistance is needed and would reduce important losses caused by this relatively new soybean disease. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? National Program 303, Plant Diseases This project will contribute to the National Program mission to reduce crop losses resulting from diseases by defining the genetic, physiological, and biochemical processes that operate in the host and pathogen
during disease development, determining influence of crop production practices on disease vulnerability, determining critical processes in pathogenesis that can be interrupted or prevented, and by identifying and manipulating new and existing sources of resistance to root diseases of soybean. Although bridging slightly into a couple of other components, the project will make primary contributions in Component 4 - Pathogen Biology, Genetics, Population Biology, Spread and Relationship with Hosts and Vectors. New and important biotypes of major soybean pathogens regularly evolve and overcome once-effective management tactics. The ongoing soybean disease research is needed to devise effective management strategies to keep up with the changing disease situation. Documentation of new races or biotypes of major soybean pathogens and identification of host resistance permit enhancement of soybean germplasm and contributes to the development of soybean cultivars that minimize yield losses
caused by soybean disease pathogens. National Program 301, Plant, microbial, and insect germplasm conservation and development is officially identified and is directly related but specific objectives are not identified. Germplasm enhancement relative to disease resistance is addressed by ongoing cooperative research with breeders and by the coordination of the USDA Uniform Soybean Tests Northern Region assigned to this project by the USDA-ARS National Program Staff. 2. List the milestones (indicators of progress) from your Project Plan. Objective 1 Research Component: Identify and describe predominant strains of root rot pathogens (Phytophthora sojae and Fusarium solani f. sp. glycines) and assess the effectiveness of soybean resistance genes for incorporation into improved germplasm. Data for P. sojae will be developed utilizing plant and soil samples from random production fields whereas plant samples from selected production fields will be used for the F. solani f. sp. glycines
data. Milestone 1: Develop population and race dynamics year-1 data base (FY2004) Milestone 2: Develop population and race dynamics year-2 data base (FY2005) Milestone 3: Develop population and race dynamics year-3 data base (FY2006) Milestone 4: Complete analysis for population and race dynamics and evaluate data (FY2007) Objective 2 Research Component: Identify and determine genetic variability of new and established Phytophthora sojae races currently maintained by this project for germplasm enhancement and race identification of new field isolates. Milestone 1: Procure and verify virulence of selected races (new & geographical) and begin developing AFLP analysis protocol (FY2004) Milestone 2: Develop AFLP analysis protocol, analyze profiles, and determine genetic relationships (FY2005) Milestone 3: Complete analysis and evaluate data (2006) Objective 3 Research Component: Determine the impact of infection at different stages of host development on severity of SDS to reveal
potentially vulnerable phases in the disease cycle. Colonization data for F. solani f. sp. glycines and other F. solani strains (non-toxin producers will be developed based on root samples but seed and root samples will be used for the Diaporthe/Phomopsis data. Milestone 1: Develop population dynamics for pathogens and soybean yield - yr-1 (FY2004) Milestone 2: Develop population dynamics for pathogens and soybean yield - yr-2; and, refine assay for greenhouse evaluation of toxin strains (FY2005) Milestone 3: Develop population dynamics for pathogens and soybean yield - yr-3; Complete analysis of Diaporthe/Phomopsis spp. based on data for two years (FY2006) Milestone 4: Complete analysis of F. solani strains based on data for three years (FY2007) Objective 4 Research Component: Determine the influence of crop management practices on root colonization of Fusarium solani f. sp. glycines and population dynamics of Phytophthora sojae races in soybean field plots. Data for P. sojae
will utilize samples from established tillage plots with a history (>6-yrs) of resistant (Rps1-k) vs. susceptible (rps) soybean cultivars in a corn-soybean and continuous soybean production system. Disease data for F. solani f. sp. glycines will involve studies in the established tillage-rotation (c-s and s-s) plots and the IPM plots that include wheat in the rotation (c-s, s-s, and c-s-w) with and without winter-crop management. Milestone 1: Develop population and race dynamics year-1 data base (FY2004) Milestone 2: Develop population and race dynamics year-2 data base (FY2005) Milestone 3: Complete P. sojae analysis based on yr-1 and yr-2 data; Continue to develop population dynamics year-3 database for F. solani f. sp. glycines (FY2006) Milestone 4: Complete F. solani f. sp. glycines analysis for population dynamics and evaluate data (FY2007) 3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met,
substantially met, or not met. If not met, why. 1. Develop populations and race dynamics year-2 data base Milestone Substantially Met 2. Develop AFLP analysis protocol, analyze profiles, and determine genetic relationships. Milestone Not Met Progress slowed by resource limitation (human,fiscal,equipment, etc. 3. Develop populations dynamics for pathogens and soybean yield - yr-2: and, refine asay for greenhouse evaluation of toxin strains. Milestone Substantially Met 4. Develop population and race year-2 data base. Milestone Substantially Met 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? During FY2006 milestone 3 for each of the four objectives should be completed. Year-3 data involving population dynamics for the root-rot pathogens are scheduled for Objectives 1, 3, and 4. Development of the AFLP analysis protocol, profile analysis, and
determination of genetic relationships for selected P. sojae races are scheduled for Objective 2. Milestone 4 for objectives 1,3, and 4 are scheduled to be completed during FY2007; this involves finalizing analysis of population dynamics for the primary root rot pathogens based on three years of data. For objectives 2 milestone 3 is somewhat rescheduled and should be completed in early FY2007. During FY2008 new objectives and milestones will be developed and/or revised based on a new CRIS project. The following narrative provides additional insights about the anticipated accomplishments of the Project Plan listed above and includes pertinent information about activities involving the project's P. sojae culture collection, germplasm enhancement and coordination of the `northern states uniform soybean tests'. Long-term studies to verify and update the frequency of predominant races or biotypes of Phytophthora sojae and Fusarium solani in Indiana soybean production fields are cardinal
to this project. This information is needed to document changes in the pathogens and to develop control strategies. In addition, we will continue to identify and provide selected P. sojae races (i.e. races 1, 3, 4, 7, 25, and 28) that can be utilized in the 'Soybean Pathogen Germplasm' initiative currently being coordinated by Dr. Dan Phillips, University of Georgia, and Dr. Peter Bretting, USDA-ARS, NPS. Additional information about the soybean pathogen germplasm initiative (i.e., Phytophthora sojae and Heterodera glycines germplasm) and the uniform soybean tests involving this project is available in the subordinate project reports. Virulence evaluations of isolates in the culture collections are critical to germplasm enhancement and have to be documented regularly. Evaluations will be expanded to include additional sources of soybean PR-differentials. Preliminary disease reactions of the selected Plant Introductions identified in previous years (parent research project) merit
additional evaluation and the elite lines will be used in adding disease resistance to improved breeding lines. The selected germplasm has a high potential for resistance to most races of Phytophthora sojae and/or Fusarium solani. Data from the SDS field evaluations will provide important information on the value of resistance for this relatively new disease of soybean and also document the correlation of field and greenhouse data involving SDS. Studies to identify potentially new sources of Phytophthora resistance previously initiated using seed of 36 selected Plant Introduction are being increased and will be revaluated. This germplasm appears to have new (i.e. Rps8) and possibly other unique P. sojae resistance traits based on preliminary data and will be evaluated to determine the genetic control. Crosses performed with several of the Plant Introduction were established in collaboration with the Purdue soybean breeder, Dr. Alan Leroy. In additional collaborative efforts, soybean
germplasm with enhanced seed composition and specialty germplasm for the vegetable market will be evaluated for Phytophthora resistance. Dr. Leroy established crosses to incorporate Rps8 and Rps gene combination (Rps1-k + 3-a and Rps1-c + 3a) in advanced Leroy established crosses to incorporate Rps8 and Rps gene combination (Rps1-k + 3-a and Rps1-c + 3a) in advanced breeding lines with potential for the vegetable market and in several advanced lines with enhanced seed composition that Dr. J. R. Wilcox, former USDA-ARS scientist, developed. The research involving physiological and pathological studies of new and established P. sojae races common to Indiana will be continued. Germplasm enhancement studies with general and unique molecular characteristics of P. sojae races will receive more emphasis in FY2006 and FY2007 particularly for new races that appear to be widespread in occurrence and have virulence patterns somewhat similar to established races. Studies designed to evaluate
the role of management practices on Phytophthora root rot and sudden death syndrome disease are unique and enhanced by being able to conduct the research in established, long-term tillage-crop rotation plots. The information will contribute to our understanding of the role of tillage, crop rotation, and cultivar resistance in soybean. Specifically, the information will provide data relative to root colonization by F. solani f.sp. glycines, methods of assessment, and new insight about the role of Rps resistance in soybean cultivars as it (i.e., resistant Rps1-k vs. susceptible rps cultivars) impacts P. sojae population dynamics and inoculum potential of this soil borne pathogen in soybean production fields. Research to confirm the roles of the two forms of F. solani that infect soybean roots will be continued. Two forms of F. solani are regularly isolated from soybean roots. Little is known about the root rot damage caused by the two forms individually or the role of root rot in yield
reduction when foliage symptoms caused by the toxins produced by F. solani f. sp. glycines do not occur. Additional studies evaluating root colonization and foliage symptoms of SDS in soybeans are needed. These studies in combination with evaluation of resistance to SDS in diverse germplasm and advanced breeding lines will aid in identifying epidemiology aspects of the disease. The epidemiology information will contribute to our understanding of the genetic control of resistance. 4a What was the single most significant accomplishment this past year? "Rps Gene Combinations Needed to Control Phytophthora Root Rot" Soybean yield losses due to races of Phytophthora sojae that are not controlled by the Rps1-k gene have increased in recent years. Plant and soil samples from Indiana soybean fields were evaluated and compared to previous years data to identify races of the genetically diverse pathogen. Results of current research continue to identify 12 predominant races and verify a limited
number of intra-race-isolates with genotypic variability capable of defeating the new Rps8 gene (Rps8 was initially reported to control all races). New races will be defined as Rps8 is integrated into the standard soybean differentials. This 2005 race virulence information defines or documents the need for gene combinations (gene-stacking) to control Phytophthora root rot; and Rps virulence data for the P. sojae isolates suggest Rps gene combinations (1- k or 1-c + 3-a and/or the new Rp8 gene) will control races identified in soybean fields, whereas disease control using the commonly deployed Rps1- k or 1-c resistance genes would be less than 50%. This type of research provides new insights about genetic diversity and distribution of P. sojae that will provide clues to key factors influencing change in this important pathogen and it is impacting development of resistant soybean cultivars, which should result in significant economic benefit. 4b List other significant
accomplishments, if any. The need for evaluation of soybean germplasm to enhance seed yield and composition along with the need to minimize disease losses are increasing. The Northern Region USDA Uniform Soybean Tests are coordinated by this project. These tests evaluate elite, publicly developed breeding lines. Data from the tests are used to determine which advanced breeding lines merit release as germplasm or as improved cultivars for commercial production. The Lead Scientist provides disease data each year for Phytophthora root rot resistance and late season fungal infection of seed for the advanced breeding lines. Phytophthora and seed health data for the publicly developed breeding lines were reported each year in the Northern Region report compiled and distributed by this project. In addition, ongoing research with a high protein soybean cultivar C1981 developed in previous research by this project also relates to this accomplishment. This high protein soybean line approved
for release was crossed with germplasm lines to incorporate root rot resistance. Root rot resistance is important since C1981 will be used in public and private breeding programs. Soybean populations involving new and combinations of Rps genes crossed to various elite high yielding parents were also increased. Breeding lines with low seed phytic acid were increased to continue evaluating the nutritional quality of the meal in livestock feeding trials, and to evaluate phosphorus in manure from non-ruminant livestock. Seeds of low phytic acid lines have been transferred to several commercial companies and researchers via Materials Transfer Agreements. These activities will enable companies to determine how effectively the seed composition traits can be incorporated into commercial cultivars. 4d Progress report. Influence of management practice(s) on SDS of soybean: Studies documenting the role of Fusarium solani f.sp. glycines root infection and SDS yield losses in soybean with tillage
(no-till vs. conventional tillage), crop rotation, host resistance, and planting date were continued in 2005. The limited research reported in southern states has indicated SDS is more likely to occur in soybeans with minimum tillage than with conventional tillage and that crop rotation has little impact on SDS. Indiana data collected to date do not agree with this statement. Root colonization of soybean plants by F. solani and SDS yield reductions were consistently higher in tilled (conventional plow and chisel) plots than in the no-till plots. The early appearance of foliage symptoms and root infection results also indicated that soybeans with continuous cropping are more likely to develop SDS than plants in the corn-soybean or corn-soybean-wheat rotations. Also the frequency and severity of SDS in early-planted soybeans continue to be much higher than in later planted soybeans regardless of tillage or rotation. Evaluation of soybean germplasm and pathogens to minimize disease
losses: Studies established in previous years were continued in 2005 to verify and update the frequency of dominant races or biotypes of P. sojae and F. solani in soybean production fields. This information is needed to document changes in the pathogens and to develop control strategies. Management and culture of the P. sojae germplasm collection were continued in 2005. In addition, the Lead Scientist will continue to identify and provide selected P. sojae races for germplasm enhancement. Virginia State University and USDA-ARS approved the soybean cultivars Asmara, 'Randolph' and Moon Cake for release. The three vegetable varieties were jointly released in 2003, 2004 and 2005. These jointly developed 'vegetable' soybeans also have excellent mature seed agronomic qualities as wells as resistance to a number of important fungal pathogens. Mature seeds can be used for several soyfood products. 5. Describe the major accomplishments over the life of the project, including their
predicted or actual impact. Research objectives of the project address the primary needs to achieve improved disease resistance in soybean. Significant progress in the early years of the program cycle was addressed in the progress reports above and is in-line with the milestones. Identification of predominant P. sojae races and race isolates capable of defeating the Rps8 resistance gene are cardinal to the soybean industry. Also much of this information builds on accomplishments of the previous project, which is highlighted in the following paragraphs. The project research has advanced the knowledge about soybean seed composition and the need for root rot resistance to minimize losses from Phytophthora root rot and sudden death syndrome. Much of the research is innovative and is best illustrated by simply describing objectives and routinely developing data to logically identify and describe unknowns (i.e., potentially vulnerable phases in a disease cycle). The following is a
recent example of innovative research by this project. It is assumed long-term usage of soybeans with specific Rps resistance genes favor development of genetically diverse Phytophthora sojae populations. Population dynamics data for P. sojae races were further verified where resistant (Rps1-k) vs. susceptible (Rps) soybean cultivars had been planted for more than 10-years. Thirteen races were identified. The race diversity was similar whether a resistant or susceptible cultivar was grown during the previous decade. However, P. sojae had 5-times the population density in field plots where susceptible cultivars had been grown compared to field plots where the resistant soybeans were planted. This new and innovative information will impact management strategies used to control this devastating soybean disease. Technology transfer has occurred regularly and information about the research is routinely requested by public and private soybean researcher, extension specialists and by
soybean producers. Several new races of Phytophthora sojae that cause root rot and extensive yield loss in soybeans were identified and compared to other races of the pathogen causing root rot of soybeans. In addition to identifying the new races, specific Rps resistance gene(s) for resistance to the races were also identified. Since several of these new P. sojae races can attack soybeans with the Rps1-k gene, information about new and dominant pathotypes of P. sojae is needed to develop effective control by Rps resistance genes. Yield reductions due to Phytophthora in Indiana are estimated at $90,000,000 annually. The race verification, population dynamics, and specific Rps gene resistance data will be useful to public and private soybean breeders for the development of cultivars that will improve resistance and minimize yield losses and help farmers select soybean cultivars resistant to Phytophthora root rot. The 'Sudden Death Syndrome' Feature article for the Plant Disease
Journal (81: 1100-1111) was co-authored and published in 1997 and continues to be requested and supplied on a regular basis. This is the first in-depth review article describing sudden death syndrome of soybean, which is still permitting soybean researchers in breeding and pathology programs to become more familiar with this relatively new soybean disease. Athow, an early maturity Group III soybean variety, was developed and released in Illinois and Indiana. The excellent yield potential, lodging resistance, and resistance to the pathogen causing Phytophthora root and stem rot of this cultivar is used regularly as a standard for new variety development and contributes to increased soybean production in the Midwest. The soybean strain C1943, with 7.6% saturated fats compared to 14.4% saturated fats of commonly grown cultivars was developed and released to the research community. This germplasm will enable public and private soybean breeders to develop and release cultivars with low
saturated fats in the oil. Two soybean strains were developed and released to the research community. C1944 and C1945 average 48.6% protein and 18.6% oil in the seed compared to currently grown cultivars that average 41.7% protein and 20.5% oil in the seed. The two germplasm releases average 89% of the yield of released cultivars. This germplasm will be useful to public and private soybean breeders for the development of improved cultivars with higher-than-normal seed protein. Two soybean mutants were created that reduce phytic acid in the seed by 50 and 70%, and that increase inorganic phosphorous in the seed by a corresponding amount. Seeds of these lines continue to be transferred to commercial companies and AES researchers through Materials Transfer Agreements. This enables additional evaluations and the companies to determine the feasibility of transferring the low phytic acid trait to commercial cultivars. USDA Uniform Soybean Tests Northern Region coordinated and report
distributed at February 2001, 2002, 2003, 2004 and 2005 Workshops. This is an annual report on the performance of advanced soybean breeding lines that have been developed by public soybean breeders in the U.S. and Canada. The report contains comprehensive data on morphological traits, agronomic performance, pest reaction, chemical composition, and herbicide sensitivity of these breeding lines. The data are results of cooperative tests, and are the basis for decisions as to which publicly developed breeding lines should be released for commercial production in the U.S. and Canada. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Compiled and distributed to soybean breeders throughout the northern US and Canada the 2004 Uniform Soybean Tests Northern
Region report in 2005. This is an annual report on the performance of advanced soybean breeding lines that have been developed by public soybean breeders in the US and Canada. The report contains comprehensive data on morphological traits, agronomic performance, pest reaction, chemical composition, and herbicide sensitivity of these breeding lines. The data are results of cooperative tests, and are the basis for decisions as to which publicly developed breeding lines should be released for commercial production in the US and Canada. The color bulletin emphasizing importance of "Rps Resistance in Soybeans" and "Frequently isolated Phytophthora sojae Races" prepared from data previously published in Plant Disease and Proc. World Soybean Res. Conf. was modified and updated using data developed in 2004. This updated "Color Flyer" identifies USDA, ARS research at Purdue University and now also includes data documenting the status of Rps gene usage in soybean cultivars available to
producers in the Midwest region of the U.S. It has been distributed and used extensively by Purdue Coop. Ext. specialists and Private Seed Companies due to the extensive development of Phytophthora problems throughout Indiana and neighboring states. Copies were distributed at the, Purdue Diagnostic Training Center, at Purdue Univ. soybean field day, and by the Purdue Diagnostic Lab to clients identifying a problem with Phytophthora root rot of soybeans. Another color bulletin emphasizing diagnostic symptoms of Sudden Death Syndrome, from data previously published in Plant Disease was modified and distributed in 2004 and 2005. Again, the Purdue Coop. Ext. specialists have used this "Color Flyer" extensively. Copies were distributed at the Certified Crop Advisors Conference sponsored by the American Agronomy Society at Purdue University, Univ. Missouri Crop & Pest Control Conference, Southwest Indiana SDS field day for Extension Educators, Crop Specialists and Farmers, and to
Agriculture Educators from counties in southwest, southeast, and central Indiana and other crop specialists from private industry; at the Purdue soybean field day; and by the Purdue Diagnostic Lab to clients identifying a problem with SDS of soybeans. The constant changing of microbial populations with time is a major constraint to long-term usage of disease information identifying dominant pathogen biotypes and soybean germplasm with specific genetic resistance. However, soybean producers will benefit from information documenting changes in the pathogen and being able to determine whether resistant soybean germplasm is needed annually. Benefits from the disease and host resistance data that are compiled and shared regularly with breeders for the development of germplasm with improved resistance may not be realized by soybean growers for about 5-7 years when new soybean varieties with improved disease resistance are released. 7. List your most important publications in the popular
press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Abney, T.S. 2004. Des Moines, IA - National Soybean Yield Summit. News release for Midwest Soybean Conference featuring insights about improving soybean yields by "Top breeders and researchers from State Universities & USDA". Communication specialist, K. Mescher, Iowa Soybean Association, developed information for a press release. Abney and some of the other researchers felt that opinions are mixed on the issue of 'stagnating soybean yields'. It was emphasized that the more research we do, the better our varieties get. Speakers provided summaries of their soybean research prior to the conference and gave presentations and participated in panel discussions during the conference. The news release was initially used to advertise the 2004 Midwest Soybean Conference; it was also published in several Midwest newspapers and popular Agriculture
Publications. This new and timely information alerted soybean researchers and producers about the importance of selecting soybean cultivars with specific Rps genes for improved control of root rot and the importance of the elite soybean germplasm developed by public researchers that is evaluated in the Uniform Soybean Tests. This elite germplasm identifies a bright light at the end of the tunnel for yield- seekers. These improved breeding lines have a high yield potential and that same germplasm will eventually make its way into varieties available to soybean growers.
Impacts
(N/A)
Publications
- Mebrahtu, T., Devine, T.E., Donald, P.A., Abney, T.S. 2005. Registration of 'Asmara' Vegetable Soybean. Crop Science. 45:408-409.
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Progress 10/01/03 to 09/30/04
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Disease resistance in soybean to root rot caused by Phytophthora sojae and Fusarium solani f.sp. glycines (= F. virguliforme) must be improved and available to breeders to minimize yield losses. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. Research objectives and approaches in this project focus on a better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations to identify and describe more effective and efficient use of resistance in soybean production. With the identification of new races of P. sojae (>18 in the 1990s) and increased inoculum potential for root rot by both P.
sojae and F. solani in soybean production fields, it is important to identify new and improved sources of resistance and to continue documenting distribution and frequency of races and strains to maximize disease control strategies. Soybean is the major oilseed crop in the world with an annual value of nearly 14 billion dollars in the U.S. Cultivars and germplasm with improved chemical composition and yield potential must have resistance to major pathogens to make production profitable. This project will focus on root rot diseases caused by Phytophthora sojae (Phytophthora root rot) and Fusarium solani f. sp. glycines (sudden death syndrome). Yield losses attributed to soybean diseases exceed 14% annually. However, Phytophthora root rot has the potential to cause much higher yield losses if resistance is not regularly incorporated into enhanced germplasm. The Rps1-k gene is currently a widely used form of resistance incorporated in cultivars, but it is not effective against race 25
and several new races identified in Indiana and Ohio during the 1990s. Recent reports by NCR- 137 and North Central Soybean Research Program (NCSRP) committees indicate that more information is needed about population dynamics of P. sojae races and about host/pathogen interactions in sudden death syndrome (SDS). Losses from SDS, a relatively new root rot disease caused by a toxin-producing strain of F. solani, are not well documented but have increased dramatically in the 1990s. Initially, SDS damage was more extensive in river floodplain areas, but now it poses a serious threat to soybeans throughout the Midwest. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. A better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations is needed and should lead to a more
effective and efficient use of resistance in soybean production. How serious is the problem? Why does it matter? Prior to the 1990s, races of Phytophthora sojae were controlled by growing soybeans with the Rps1-k gene and little is known about resistance and epidemiology of SDS caused by Fusarium solanif. sp. glycines, which is a relatively new disease of soybeans. Pathology research efforts are underway to verify the current race situation and population dynamics of P. sojae and F. solani f. sp. glycines common to Indiana soybean production fields. Representative races maintained for pathology and breeding efforts are being utilized to incorporate additional Rps genes (gene combinations and the recently identified Rps8 gene) into elite soybean breeding lines to provide improved Phytophthora resistance. Yield reductions due to Phytophthora are estimated at $124,000,000 per year for the U.S. in the 1990s. Managing Phytophthora with genetic resistance currently available would
provide full season disease control and result in significant economic benefit and reduce the need for fungicide treatment that only provides partial or temporary control. Yield reductions due to sudden death syndrome (SDS) are similar to that listed above for Phytophthora and they continue to increase throughout the Midwest states. Almost all soybean varieties are highly susceptible to SDS and yield losses in Indiana were common in central as well as southwest Indiana in recent years. Identification and incorporation of genetic resistance is needed and would reduce important losses caused by this relatively new soybean disease. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? National Program 303, Plant Diseases (100%) This project will contribute to the National Program mission to reduce crop losses resulting from diseases by defining the genetic, physiological, and biochemical processes that operate in the host and
pathogen during disease development, determining influence of crop production practices on disease vulnerability, determining critical processes in pathogenesis that can be interrupted or prevented, and by identifying and manipulating new and existing sources of resistance to root diseases of soybean. Although bridging slightly into a couple of other components, the project will make primary contributions in Component 4 - Pathogen Biology, Genetics, Population Biology, Spread and Relationship with Hosts and Vectors. New and important biotypes of major soybean pathogens regularly evolve and overcome once-effective management tactics. The ongoing soybean disease research is needed to devise effective management strategies to keep up with the changing disease situation. Documentation of new races or biotypes of major soybean pathogens and identification of host resistance permit enhancement of soybean germplasm and contributes to the development of soybean cultivars that minimize
yield losses causes by soybean disease pathogens. National Program 301, Plant, microbial, and insect germplasm conservation and development is not officially identified but is directly related. Germplasm enhancement relative to disease resistance is addressed by ongoing cooperative research with breeders and by the coordination of the USDA Uniform Soybean Tests Northern Region assigned to this project by the USDA-ARS National Program Staff. 2. List the milestones (indicators of progress) from your Project Plan. Objective 1 Research Component: Identify and describe predominant strains of root rot pathogens (Phytophthora sojae and Fusarium solani f. sp. glycines) and assess the effectiveness of soybean resistance genes for incorporation into improved germplasm. Data for P. sojae will be developed utilizing plant and soil samples from random production fields whereas plant samples from selected production fields will be used for the F. solani f. sp. glycines data. Milestone 1: Develop
population and race dynamics year-1 data base (FY2004) Milestone 2: Develop population and race dynamics year-2 data base (FY2005) Milestone 3: Develop population and race dynamics year-3 data base (FY2006) Milestone 4: Complete analysis for population and race dynamics and evaluate data (FY2007) Objective 2 Research Component: Identify and determine genetic variability of new and established Phytophthora sojae races currently maintained by this project for germplasm enhancement and race identification of new field isolates. Milestone 1: Procure and verify virulence of selected races (new & geographical) and begin developing AFLP analysis protocol (FY2004) Milestone 2: Develop AFLP analysis protocol, analyze profiles, and determine genetic relationships (FY2005) Milestone 3: Complete analysis and evaluate data (2006) Objective 3 Research Component: Determine the impact of infection at different stages of host development on severity of SDS to reveal potentially vulnerable
phases in the disease cycle. Colonization data for F. solani f. sp. glycines and other F. solani strains (non-toxin producers will be developed based on root samples but seed and root samples will be used for the Diaporthe/Phomopsis data. Milestone 1: Develop population dynamics for pathogens and soybean yield - yr-1 (FY2004) Milestone 2: Develop population dynamics for pathogens and soybean yield - yr-2; and, refine assay for greenhouse evaluation of toxin strains (FY2005) Milestone 3: Develop population dynamics for pathogens and soybean yield - yr-3; Complete analysis of Diaporthe/Phomopsis spp. based on data for two years (FY2006) Milestone 4: Complete analysis of F. solani strains based on data for three years (FY2007) Objective 4 Research Component: Determine the influence of crop management practices on root colonization of Fusarium solani f. sp. glycines and population dynamics of Phytophthora sojae races in soybean field plots. Data for P. sojae will utilize samples from
established tillage plots with a history (>6-yrs) of resistant (Rps1-k) vs. susceptible (rps) soybean cultivars in a corn-soybean and continuous soybean production system. Disease data for F. solani f. sp. glycines will involve studies in the established tillage-rotation (c-s and s-s) plots and the IPM plots that include wheat in the rotation (c-s, s-s, and c-s-w) with and without winter-crop management. Milestone 1: Develop population and race dynamics year-1 data base (FY2004) Milestone 2: Develop population and race dynamics year-2 data base (FY2005) Milestone 3: Complete P. sojae analysis based on yr-1 and yr-2 data; Continue to develop population dynamics year-3 data base for F. solani f. sp. glycines (FY2006) Milestone 4: Complete F. solani f. sp. glycines analysis for population dynamics and evaluate data (FY2007) 3. Milestones: A. List the milestones (from the list in Question #2) that were scheduled to be addressed in FY 2004. How many milestones did you fully or
substantially meet in FY 2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. Objective 1 milestones and expected outcomes involve studies to identify year-1 population and race dynamics for P. sojae and F. solani f.sp. glycines. Plant and soil samples from random production fields are used for the Phytophthora data, but only plants from selected fields are used for the Fusarium data. Objective 2 milestones and expected outcomes involve studies to procure additional P. sojae isolates (new & geographical) of selected races, and to verify virulence. Development of a protocol for the AFLP analysis to analyze profiles, analyze profiles, and determine genetic relationships are also identified. Objective 3 milestones and expected outcomes involve studies to identify year-1 sudden death syndrome severity in soybeans inoculated with the toxin producing stain (f.sp. glycines) of F. solani. Disease severity data (year-1) for
soybean yield and root colonization in inoculated vs. non-inoculated will be documented. Root colonization data will include population dynamics for the SDS pathogen (F. solani f. sp. glycines), other F. solani strains (non-toxin producers) and Diaporthe/Phomopsis spp. Objective 4 milestones and expected outcomes involve studies to determine influence of crop management on sudden death syndrome and Phytophthora root rot. Data (year-1) for disease severity, soybean yield, and population dynamics for the two disease pathogens are identified. The P. sojae population and race dynamics information includes data for both plant and soil samples from tillage (reduced vs. conventional tillage) rotation plots, but the F. solani f. sp. glycines information is based only on plant samples. The influence of host resistance on P. sojae population and race dynamics includes data for established plots with a history of more than six years of Rps1-k vs. rps soybean cultivar(s) production. The
milestones and expected outcomes for objectives 1, 3, and 4 were fully or substantially met in FY2004. However, for objective 2 they were only partially met. Additional P. sojae isolates (new and geographic) of selected races were procured and virulence verified, but development of a protocol for the AFLP analysis to analyze profiles is not finalized. This activity has been delayed until personnel (i.e., graduate student or post-doctoral researcher) with qualifications to conduct the AFLP analysis can be recruited. B. List the milestones (from the list in Question #2) that you expect to address over the next 3 years (FY2005, FY2006, FY2007). What do you expect to accomplish, year by year, over the next 3 years for each milestone? During FY2005 milestone 2 for each of the four objectives should be completed. Year-2 data involving population dynamics for the root-rot pathogens are scheduled for Objectives 1, 3, and 4. Development of the AFLP analysis protocol, profile analysis,
and determination of genetic relationships for selected P. sojae races are scheduled for Objective 2. Milestone 3 for each of the objectives are scheduled to be completed during FY2006.; and milestone 4 (complete analysis of population dynamics for the primary root rot pathogens based on three years of data) for objectives 1,3, and 4 are scheduled to be completed during FY2007. The following narrative provides additional insights about the anticipated accomplishments of the Project Plan listed above and includes pertinent information about activities involving the project's P. sojae culture collection, germplasm enhancement and coordination of the 'northern states uniform soybean tests'. Long-term studies to verify and update the frequency of predominant races or biotypes of Phytophthora sojae and Fusarium solani in Indiana soybean production fields are cardinal to this project. This information is needed to document changes in the pathogens and to develop control strategies. In
addition, we will continue to identify and provide selected P. sojae races (i.e. races 1, 3, 4, 7, 25, and 28) that can be utilized in the 'Soybean Pathogen Germplasm' initiative currently being coordinated by Dr. Dan Phillips, University of Georgia, and Dr. Peter Bretting, USDA-ARS, NPS. Additional information about the soybean pathogen germplasm initiative (i.e., Phytophthora sojae and Heterodera glycines germplasm) and the uniform soybean tests involving this project is available in the subordinate project reports. Virulence evaluations of isolates in the culture collections are critical to germplasm enhancement and have to be documented regularly. Evaluations will be expanded to include additional sources of soybean PR-differentials. Seed of several PR-differentials is increased each year to enhance race verification and for distribution to soybean researchers. The P. sojae race collection maintained for use in the pathology and breeding programs supported by this project are also
needed for germplasm enhancement by numerous seed companies. Selected isolates and races with referenced virulence are also needed and used regularly for critical reference in identifying new and wild biotypes of the pathogens. Preliminary disease reactions of the selected Plant Introductions identified in previous years (parent research project) merit additional evaluation and the elite lines will be used in adding disease resistance to improved breeding lines. The selected germplasm has a high potential for resistance to most races of Phytophthora sojae and/or Fusarium solani. Data from the SDS field evaluations will provide important information on the value of resistance for this relatively new disease of soybean and also document the correlation of field and greenhouse data involving SDS. Studies to identify potentially new sources of Phytophthora resistance previously initiated using seed of 36 selected Plant Introduction are being increased and will be revaluated. This
germplasm appears to have new (i.e. Rps8) and possibly other unique P. sojae resistance traits based on preliminary data and will be evaluated to determine the genetic control. Crosses performed with several of the Plant Introduction were established in collaboration with the Purdue soybean breeder, Dr. Alan Leroy. In additional collaborative efforts, soybean germplasm with enhanced seed composition and specialty germplasm for the vegetable market will be evaluated for Phytophthora resistance. Dr. Leroy established crosses to incorporate Rps8 and Rps gene combination (Rps1-k + 3-a and Rps1-c + 3a) in advanced breeding lines with potential for the vegetable market and in several advanced lines with enhanced seed composition that Dr. J. R. Wilcox, former USDA- ARS scientist, developed. The research involving physiological and pathological studies of new and established P. sojae races common to Indiana will be continued. Germplasm enhancement studies with general and unique molecular
characteristics of P. sojae races will receive more emphasis in FY2005 and FY2006 particularly for new races that appear to be widespread in occurrence and have virulence patterns somewhat similar to established races. Isolates of P. sojae initially selected for DNA fingerprinting will consist of eight races (1,3,4,7,25,33,43, and 44). Amplified fragment length polymorphism (AFLP) techniques will be used to determine unique, race-specific markers and to establish genetic relationship among specific races. Studies designed to evaluate the role of management practices on Phytophthora root rot and sudden death syndrome disease are unique and enhanced by being able to conduct the research in established, long-term tillage-crop rotation plots. The information will contribute to our understanding of the role of tillage, crop rotation, and cultivar resistance in soybean. Specifically, the information will provide data relative to root colonization by F. solani f.sp. glycines, methods of
assessment, and new insight about the role of Rps resistance in soybean cultivars as it (i.e., resistant Rps1-k vs. susceptible rps cultivars) impacts P. sojae population dynamics and inoculum potential of this soilborne pathogen in soybean production fields. Research to confirm the roles of the two forms of F. solani that infect soybean roots will be continued. Two forms of F. solani are regularly isolated from soybean roots. Little is known about the root rot damage caused by the two forms individually or the role of root rot in yield reduction when foliage symptoms caused by the toxins produced by F. solani f. sp. glycines do not occur. Additional studies evaluating root colonization and foliage symptoms of SDS in soybeans are needed. These studies in combination with evaluation of resistance to SDS in diverse germplasm and advanced breeding lines will aid in identifying epidemiology aspects of the disease. The epidemiology information will contribute to our understanding of the
genetic control of resistance. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY 2004: Soybean yield losses due to races of Phytophthora sojae that are not controlled by the Rps1-k gene have increased in recent years. Plant and soil samples from Indiana soybean fields were evaluated and compared to previous years data to identify races of the genetically diverse pathogen. Results of current research now identify 12 predominant races and verify a need for gene combinations or the new Rps8 gene to control Phytophthora root rot; and Rps virulence data for the isolates suggest Rps gene combinations (1-k or 1-c + 3-a) or the new Rps8 gene will control races identified in soybean fields, whereas disease control using Rps1-k or 1-c resistance genes would be less than 50%. This type of research provides new insights about genetic diversity and distribution of P. sojae that will provide clues to key factors influencing change
in this important pathogen and it is impacting development of resistant soybean cultivars, which should result in significant economic benefit. B. Other Significant Accomplishments: The need for evaluation of soybean germplasm to enhance seed yield and composition along with the need to minimize disease losses are increasing. The Northern Region USDA Uniform Soybean Tests are coordinated by this project. These tests evaluate elite, publicly developed breeding lines. Data from the tests are used to determine which advanced breeding lines merit release as germplasm or as improved cultivars for commercial production. The Lead Scientist provides disease data each year for Phytophthora root rot resistance and late season fungal infection of seed for the advanced breeding lines. Phytophthora and seed health data for the publicly developed breeding lines were reported each year in the Northern Region report compiled and distributed by this project. In addition, ongoing research with a high
protein soybean cultivar C1981 developed in previous research by this project also relates to this accomplishment. This high protein soybean lines approved for release was crossed with germplasm lines to incorporate root rot resistance. Root rot resistance is important since C1981 will be used in public and private breeding programs. Soybean populations involving new and combinations of Rps genes crossed to various elite high yielding parents were also increased. Breeding lines with low seed phytic acid were increased to continue evaluating the nutritional quality of the meal in livestock feeding trials, and to evaluate phosphorus in manure from non-ruminant livestock. Seeds of low phytic acid lines have been transferred to two commercial companies and researchers via Materials Transfer Agreements. These activities will enable companies to determine how effectively the seed composition traits can be incorporated into commercial cultivars. C. Significant Activities that Support
Special Target Populations: None. D. Progress Report: Influence of management practice(s) on SDS of soybean: Studies documenting the role of Fusarium solani f.sp. glycines root infection and SDS yield losses in soybean with tillage (no-till vs. conventional tillage), crop rotation, host resistance, and planting date were continued in 2004. The limited research reported in southern states has indicated SDS is more likely to occur in soybeans with minimum tillage than with conventional tillage and that crop rotation has little impact on SDS. Indiana data collected to date do not agree with this statement. Root colonization of soybean plants by F. solani and SDS yield reductions were consistently higher in conventional tillage plots than in the no- till plots. The early appearance of foliage symptoms and root infection results also indicated that soybeans with continuous cropping are more likely to develop SDS than plants in the corn-soybean or corn-soybean- wheat rotations. Also the
frequency and severity of SDS in early-planted soybeans has been much higher than in later planted soybeans regardless of tillage or rotation. Evaluation of soybean germplasm and pathogens to minimize disease losses: Studies established in previous years were continued in 2004 to verify and update the frequency of dominant races or biotypes of P. sojae and F. solani in soybean production fields. This information is needed to document changes in the pathogens and to develop control strategies. Management and culture of the P. sojae germplasm collection were continued in 2004. In addition, the Lead Scientist will continue to identify and provide selected P. sojae races for germplasm enhancement. Virginia State University and USDA-ARS approved the soybean cultivar 'Randolph' for release. This is the second vegetable variety jointly released in 2003 and 2004. These jointly developed 'vegetable' soybeans also have excellent mature seed agronomic qualities as wells as resistance to a
number of important fungal pathogens. Mature seeds can be used for several soyfood products. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Research objectives of the project address the primary needs to achieve improved disease resistance in soybean. Significant progress in years 1 and 2 of the program cycle were addressed in the progress reports above and are in-line with the milestones. Much of the information builds on accomplishments of the previous project, which is highlighted in the following paragraphs. The project research has advanced the knowledge about soybean seed composition and the need for root rot resistance to minimize losses from Phytophthora root rot and sudden death syndrome. Much of the research is innovative and is best illustrated by simply describing objectives and routinely developing data to logically identify and describe unknowns (i.e., potentially vulnerable phases in a disease cycle).
The following is a recent example of innovative research by this project. It is assumed long-term usage of soybeans with specific Rps resistance genes favor development of genetically diverse Phytophthora sojae populations. Population dynamics data for P. sojae races were further verified where resistant (Rps1-k) vs. susceptible (Rps) soybean cultivars had been planted for more than 10-years. Thirteen races were identified. The race diversity was similar whether a resistant or susceptible cultivar was grown during the previous decade. However, P. sojae had 5-times the population density in field plots where susceptible cultivars had been grown compared to field plots where the resistant soybeans were planted. This new and innovative information will impact management strategies used to control this devastating soybean disease. Technology transfer has occurred regularly and information about the research is routinely requested by public and private soybean researcher, extension
specialists and by soybean producers. Seven new races of Phytophthora sojae that cause root rot and extensive yield loss in soybeans were identified and compared to other races of the pathogen causing root rot of soybeans. In addition to identifying the new races, specific Rps resistance gene(s) for resistance to the races were also identified. Since several of these new P. sojae races can attack soybeans with the Rps1-k gene, information about new and dominant pathotypes of P. sojae is needed to develop effective control by Rps resistance genes. Yield reductions due to Phytophthora in Indiana are estimated at $90,000,000 annually. The race verification, population dynamics, and specific Rps gene resistance data will be useful to public and private soybean breeders for the development of cultivars that will improve resistance and minimize yield losses and help farmers select soybean cultivars resistant to Phytophthora root rot. The 'Sudden Death Syndrome' Feature article for the
Plant Disease Journal (81: 1100-1111) was co-authored and published in 1997 and continues to be requested and supplied on a regular basis. This is the first in-depth review article describing sudden death syndrome of soybean, which is still permitting soybean researchers in breeding and pathology programs to become more familiar with this relatively new soybean disease. Athow, an early maturity Group III soybean variety, was developed and released in Illinois and Indiana. The excellent yield potential, lodging resistance, and resistance to the pathogen causing Phytophthora root and stem rot of this cultivar is used regularly as a standard for new variety development and contributes to increased soybean production in the Midwest. The soybean strain C1943, with 7.6% saturated fats compared to 14.4% saturated fats of commonly grown cultivars was developed and released to the research community. This germplasm will enable public and private soybean breeders to develop and release
cultivars with low saturated fats in the oil. Two soybean strains were developed and released to the research community. C1944 and C1945 average 48.6% protein and 18.6% oil in the seed compared to currently grown cultivars that average 41.7% protein and 20.5% oil in the seed. The two germplasm releases average 89% of the yield of released cultivars. This germplasm will be useful to public and private soybean breeders for the development of improved cultivars with higher-than-normal seed protein. Two soybean mutants were created that reduce phytic acid in the seed by 50 and 70%, and that increase inorganic phosphorous in the seed by a corresponding amount. Seeds of these lines were transferred to commercial companies and AES researchers through Materials Transfer Agreements. This will enable additional evaluations and the companies to determine the feasibility of transferring the low phytic acid trait to commercial cultivars. USDA Uniform Soybean Tests Northern Region coordinated
and report distributed at February 2001, 2002, 2003 and 2004 Workshops. This is an annual report on the performance of advanced soybean breeding lines that have been developed by public soybean breeders in the U.S. and Canada. The report contains comprehensive data on morphological traits, agronomic performance, pest reaction, chemical composition, and herbicide sensitivity of these breeding lines. The data are results of cooperative tests, and are the basis for decisions as to which publicly developed breeding lines should be released for commercial production in the U.S. and Canada. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Compiled and distributed to soybean breeders throughout the northern US and Canada the 2003 Uniform Soybean Tests
Northern Region report in 2004. This is an annual report on the performance of advanced soybean breeding lines that have been developed by public soybean breeders in the US and Canada. The report contains comprehensive data on morphological traits, agronomic performance, pest reaction, chemical composition, and herbicide sensitivity of these breeding lines. The data are results of cooperative tests, and are the basis for decisions as to which publicly developed breeding lines should be released for commercial production in the US and Canada. The color bulletin emphasizing importance of "Rps Resistance in Soybeans" and "Frequently isolated Phytophthora sojae Races" prepared from data previously published in Plant Disease and Proc. World Soybean Res. Conf. was modified and updated using data developed in 2003. This updated "Color Flyer" identifies USDA, ARS research at Purdue University and now also includes data documenting the status of Rps gene usage in soybean cultivars available
to producers in the Midwest region of the U.S. It has been distributed and used extensively by Purdue Coop. Ext. specialists and Private Seed Companies due to the extensive development of Phytophthora problems throughout Indiana and neighboring states. Copies were distributed at the, Purdue Diagnostic Training Center, at Purdue Univ. soybean field day, and by the Purdue Diagnostic Lab to clients identifying a problem with Phytophthora root rot of soybeans. Another color bulletin emphasizing diagnostic symptoms of Sudden Death Syndrome, from data previously published in Plant Disease was modified and distributed in 2003 and 2004. Again, the Purdue Coop. Ext. specialists have used this "Color Flyer" extensively. Copies were distributed at the Certified Crop Advisors Conference sponsored by the American Agronomy Society at Purdue University, Univ. Missouri Crop & Pest Control Conference, Southwest Indiana SDS field day for Extension Educators, Crop Specialists and Farmers, and to
Agriculture Educators from counties in southwest, southeast, and central Indiana and other crop specialists from private industry; at the Purdue soybean field day; and by the Purdue Diagnostic Lab to clients identifying a problem with SDS of soybeans. The constant changing of microbial populations with time is a major constraint to long-term usage of disease information identifying dominant pathogen biotypes and soybean germplasm with specific genetic resistance. However, soybean producers will benefit from information documenting changes in the pathogen and being able to determine whether resistant soybean germplasm is needed annually. Benefits from the disease and host resistance data that are compiled and shared regularly with breeders for the development of germplasm with improved resistance may not be realized by soybean growers for about 5-7 years when new soybean varieties with improved disease resistance are released. 7. List your most important publications in the popular
press and presentations to organizations and articles written about your work. Abney, T.S. 2004. Des Moines, IA - National Soybean Yield Summit. News release for Midwest Soybean Conference featuring insights about improving soybean yields by "Top breeders and researchers from State Universities & USDA". Communication specialist, K. Mescher, Iowa Soybean Association, developed information for a press release. Abney and some of the other researchers felt that opinions are mixed on the issue of 'stagnating soybean yields'. It was emphasized that the more research we do, the better our varieties get. Speakers provided summaries of their soybean research prior to the conference and gave presentations and participated in panel discussions during the conference. The news release was initially used to advertise the 2004 Midwest Soybean Conference; it was also published in several Midwest newspapers and popular Agriculture Publications. This new 2004 information alerted soybean
researchers and producers about the importance of selecting soybean cultivars with specific Rps genes for improved control of root rot and the importance of the elite soybean germplasm developed by public researchers that is evaluated in the Uniform Soybean Tests. This elite germplasm identifies a bright light at the end of the tunnel for yield-seekers. These improved breeding lines have a high yield potential and that same germplasm will eventually make its way into varieties available to soybean growers.
Impacts
(N/A)
Publications
- Dorrance, A.E., Jia, H., Abney, T.S. 2004. Evaluation of soybean differentials for their interaction with phytophthora sojae. Plant Health Progress. 0309(1). Available: http://www.plantmanagementnetwork. org/sub/php/research/2004/psojae/
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Progress 10/01/02 to 09/30/03
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Disease resistance in soybean to root rot caused by Phytophthora sojae and Fusarium solani f.sp. glycines must be improved and available to breeders to minimize yield losses. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. Research objectives and approaches in this project focus on a better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations to identify and describe more effective and efficient use of resistance in soybean production. With the identification of new races of P. sojae (>18 in the 1990s) and increased inoculum potential for root rot by both P. sojae and F. solani in soybean production fields, it is important to identify new and improved sources of
resistance and to continue documenting distribution and frequency of races and strains to maximize disease control strategies. Soybean is the major oilseed crop in the world with an annual value of nearly 14 billion dollars in the U.S. Cultivars and germplasm with improved chemical composition and yield potential must have resistance to major pathogens to make production profitable. This project will focus on root rot diseases caused by Phytophthora sojae (Phytophthora root rot) and Fusarium solani f. sp. glycines (sudden death syndrome). Yield losses attributed to soybean diseases exceed 14% annually. However, Phytophthora root rot has the potential to cause much higher yield losses if resistance is not regularly incorporated into enhanced germplasm. The Rps1-k gene is currently a widely used form of resistance incorporated in cultivars, but it is not effective against race 25 and several new races identified in Indiana and Ohio during the 1990s. Recent reports by NCR- 137 and North
Central Soybean Research Program (NCSRP) committees indicate that more information is needed about population dynamics of P. sojae races and about host/pathogen interactions in sudden death syndrome (SDS). Losses from SDS, a relatively new root rot disease caused by a toxin-producing strain of F. solani, are not well documented but have increased dramatically in the 1990s. Initially, SDS damage was more extensive in river floodplain areas, but now it poses a serious threat to soybeans throughout the Midwest. The lack of basic knowledge concerning these two important soybean pathogens is a limiting factor restricting the development of improved control strategies and the ability to predict the severity of future outbreaks. A better understanding of the genetic basis of host resistance and genetic structure of these pathogen populations is needed and should lead to a more effective and efficient use of resistance in soybean production. 2. How serious is the problem? Why does it
matter? Prior to the 1990s, races of Phytophthora sojae were controlled by growing soybeans with the Rps1-k gene and little is known about resistance and epidemiology of SDS caused by Fusarium solani f. sp. glycines, which is a relatively new disease of soybeans. Pathology research efforts are underway to verify the current race situation and population dynamics of P. sojae and F. solani f. sp. glycines common to Indiana soybean production fields. Representative races maintained for pathology and breeding efforts are being utilized to incorporate additional Rps genes (gene combinations and the recently identified Rps8 gene) into elite soybean breeding lines to provide improved Phytophthora resistance. Yield reductions due to Phytophthora are estimated at $124,000,000 per year for the U.S. in the 1990s. Managing Phytophthora with genetic resistance currently available would provide full season disease control and result in significant economic benefit and reduce the need for fungicide
treatment that only provides partial or temporary control. Yield reductions due to sudden death syndrome (SDS) are similar to that listed above for Phytophthora and they continue to increase throughout the Midwest states. Almost all soybean varieties are highly susceptible to SDS and yield losses in Indiana were common in central as well as southwest Indiana in recent years. Identification and incorporation of genetic resistance is needed and would reduce important losses caused by this relatively new soybean disease. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? National Program 303, Plant Diseases (100%) This project will contribute to the National Program mission to reduce crop losses resulting from diseases by defining the genetic, physiological, and biochemical processes that operate in the host and pathogen during disease development, determining influence of crop production practices on disease vulnerability,
determining critical processes in pathogenesis that can be interrupted or prevented, and by identifying and manipulating new and existing sources of resistance to root diseases of soybean. Although bridging slightly into a couple of other components, the project will make primary contributions in Component 4 - Pathogen Biology, Genetics, Population Biology, Spread and Relationship with Hosts and Vectors. New and important biotypes of major soybean pathogens regularly evolve and overcome once-effective management tactics. The ongoing soybean disease research is needed to devise effective management strategies to keep up with the changing disease situation. Documentation of new races or biotypes of major soybean pathogens and identification of host resistance permit enhancement of soybean germplasm and contributes to the development of soybean cultivars that minimize yield losses causes by soybean disease pathogens. National Program 301, Plant, microbial, and insect germplasm
conservation and development is not officially identified but is directly related. Germplasm enhancement relative to disease resistance is addressed by ongoing cooperative research with breeders and by the coordination of the USDA Uniform Soybean Tests Northern Region assigned to this project by the USDA-ARS National Program Staff. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY 2003: Soybean yield losses due to races of Phytophthora sojae that are not controlled by the Rps1-k gene have increased in recent years. Plant and soil samples from Indiana soybean fields were evaluated and compared to previous years data to identify races of the genetically diverse pathogen. Results of 2002 research still identify ten predominant races and verify a need for gene combinations to control Phytophthora root rot; and Rps virulence data for the isolates suggest Rps gene combinations (1-k or 1-c + 3-a) or the new Rps8 gene will
control races identified in soybean fields, whereas disease control using Rps1-k or 1-c resistance genes would be less than 50%. This type of research provides new insights about genetic diversity and distribution of P. sojae that will provide clues to key factors influencing change in this important pathogen and it is impacting development of resistant soybean cultivars which should result in significant economic benefit. B. Other Significant Accomplishments: It is assumed long-term usage of soybeans with specific Rps resistance genes favor development of genetically diverse Phytophthora sojae populations. Population dynamics data for P. sojae races were further verified where resistant (Rps1-k) vs. susceptible (rps) soybean cultivars had been planted for more than 10-years. Thirteen races were identified. The race diversity was similar whether a resistant or susceptible cultivar was grown during the previous decade. However, P. sojae had 5- times the population density in field
plots where susceptible cultivars had been grown compared to field plots where the resistant soybeans were planted. This new information that will impact management strategies used to control this devastating soybean disease. C. Significant Activities that Support Special Target Populations: None. D. Progress Report: Influence of tillage and rotation on SDS of soybean: Studies documenting the role of Fusarium solani f.sp. glycines root infection and SDS yield losses in soybean with tillage (no-till vs. conventional tillage) and crop rotation were continued in 2003. The limited research reported in southern states has indicated that SDS is more likely to occur in soybeans with minimum tillage than with conventional tillage. Indiana data collected from 2002 does not agree with this statement. Root colonization of soybean plants by F. solani and SDS yield reductions were consistently higher in conventional tillage plots than in the no-till plots. The root infection results also
indicated that soybeans with continuous cropping are more likely to develop SDS than plants in the corn-soybean rotation. Evaluation of soybean germplasm and pathogens to minimize disease losses: Studies were established in 2003 to continue verifying and updating the frequency of dominant races or biotypes of P. sojae and F. solani in soybean production fields. This information is needed to document changes in the pathogens and to develop control strategies. Management and culture of the P. sojae germplasm collection were continued in 2003. In addition, the Lead Scientist will continue to identify and provide selected P. sojae races for germplasm enhancement. Virginia State University and USDA-ARS approved the soybean cultivar 'Asmara' for release in 2003. This jointly developed 'vegetable' soybean also has excellent mature seed agronomic qualities as wells as resistance to a number of important fungal pathogens. Mature seeds can be used for several soyfood products. Soybean disease
information for part of an Online- and CD-Rom Publication was completed that includes more than 20 different fungal diseases, five viral diseases, and three bacterial diseases. The diagnostic symptom of each disease is illustrated and information relative to management and control are described. The information describing symptoms, disease cycle, and control outlined in this Extension Publication will provide crop specialists and soybean growers current insight into disease diagnosis and management practices that will reduce disease losses. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. This is a new project based on a Project Plan certified by the OSQR 02/12/03, replacing 3602-21220-007-00D entitled Enhancing Soybean Seed Composition and Pest Resistance. Research objectives of the new project address the primary needs to achieve improved disease resistance in soybean. The four major objectives are below: 1. Identify
and describe predominant strains of root rot pathogens and assess the effectiveness of soybean resistance genes for incorporation into improved germplasm. 2. Identify and determine genetic variability of new and established Phytophthora sojae races currently maintained by this project for germplasm enhancement and race identification of new field isolates. 3. Determine the impact of infection at different stages of host development on severity of SDS to reveal potentially vulnerable phases in the disease cycle. 4. Determine the influence of crop management practices on root colonization of Fusarium solani f. sp. glycines and population dynamics of P. sojae races in soybean field plots. 6. What do you expect to accomplish, year by year, over the next 3 years? The following are anticipated accomplishments of the new Project Plan. FY 2004: We will conduct further studies to verify and update the frequency of dominant races or biotypes of Phytophthora sojae and Fusarium solani in
Indiana soybean production fields. This information is needed to document changes in the pathogens and to develop control strategies. In addition, we will continue to identify and provide selected P. sojae races (i.e. races 1, 3, 4, 7, 25, and 28) that can be utilized in the 'Soybean Pathogen Germplasm' initiative currently being coordinated by Dr. Dan Phillips, University of Georgia, and Dr. Peter Bretting, USDA-ARS, NPS. Virulence evaluations of isolates in the culture collections are critical to germplasm enhancement and have to be documented regularly. Evaluations will be expanded to include additional sources of soybean PR-differentials. Seed of several PR- differentials is being increased in 2002 and 2003 to enhance race verification and for distribution to soybean researchers. The P. sojae race collection maintained for use in the pathology and breeding programs supported by this project are also needed for germplasm enhancement by numerous seed companies. Selected isolates and
races with referenced virulence are also needed and used regularly for critical reference in identifying new and wild biotypes of the pathogens. Preliminary disease reactions of the selected Plant Introductions increased in 2001 and 2002 merit additional evaluation and elite lines will be used in adding disease resistance to elite breeding lines. The selected germplasm has a high potential for resistance to most races of Phytophthora sojae and/or Fusarium solani. Data from the SDS field evaluations will provide important information on the value of resistance for this relatively new disease of soybean and also document the correlation of field and greenhouse data involving SDS. Studies to identify potentially new sources of Phytophthora resistance initiated in 2001 using seed of 36 selected Plant Introduction are being increased and evaluated in 2003. This germplasm appears to have new (i.e. Rps8) and possibly other unique P. sojae resistance traits based on preliminary data and will
be evaluated to determine the genetic control. Crosses performed with several of the Plant Introduction were established in collaboration with the Purdue soybean breeder, Dr. Alan Leroy. In additional collaborative efforts, soybean germplasm with enhanced seed composition and specialty germplasm for the vegetable market will be evaluated for Phytophthora resistance. Dr. Leroy established crosses to incorporate Rps gene combination (Rps1-k + 3-a and Rps1-c + 3a) in advanced breeding lines with potential for the vegetable market and in several advanced lines with enhanced seed composition that Dr. J. R. Wilcox, former USDA-ARS scientist, developed. FY 2005: We will continue our physiological and pathological studies of new and established P. sojae races common to Indiana. Germplasm enhancement studies with general and unique molecular characteristics of P. sojae races will receive more emphasis and particularly for new races that appear to be widespread in occurrence and have virulence
patterns somewhat similar to established races. Isolates of P. sojae initially selected for DNA fingerprinting will consist of eight races (1,3,4,7,25,33,43, and 44). Amplified fragment length polymorphism (AFLP) techniques will be used to determine unique, race-specific markers and to establish genetic relationship among specific races. Studies designed to evaluate the role of post-herbicide weed control treatments on the sudden death syndrome disease reaction of soybean lines should be finalized based on two years of field data. The information will contribute to our understanding of the role of herbicide and disease interactions in soybean. Specifically, the information will provide data relative to root colonization by F. solani f.sp. glycines, methods of assessment, and new insight about the role of the widely used 'round-up-ready' gene in soybean disease development. FY 2006: We plan to conduct further studies to confirm the roles of the two forms of F. solani that infect
soybean roots. Two forms of F. solani are regularly isolated from soybean roots. Little is known about the root rot damage caused by the two forms individually or the role of root rot in yield reduction when foliage symptoms caused by the toxins produced by F. solani f. sp. glycines do not occur. Additional studies evaluating root colonization and foliage symptoms of SDS in soybeans are needed. These studies in combination with evaluation of resistance to SDS in diverse germplasm and advanced breeding lines will aid in identifying epidemiology aspects of the disease. The epidemiology information will contribute to our understanding of the genetic control of resistance.
Impacts
(N/A)
Publications
- Schweitzer, L.E., Abney, T.S, Shaner, G.E. Soybean diseases. In Soybean Growth, Development and Diagnostics ed. L.E. Schweitzer, Purdue University Cooperative Extension AY-4. Available from: http://www.agcom.purdue. edu/AgCom/pubs/menu.htm. and Soybean Growth, Development and Diagnostics. CD-ROM. West Lafayette, IN: Purdue University. 2003.
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