Progress 03/18/01 to 07/31/05
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? The corn crop in the southeastern U.S. often suffers serious losses due to insect feeding on ears and leaves and contamination of the grain with aflatoxin, a carcinogenic mycotoxin produced by Aspergillus flavus. The losses associated with insect damage to the ears exacerbate the infection of the grain by A. flavus and increase subsequent contamination by aflatoxin. The chronic problems of insect damage and aflatoxin contamination drastically reduce the quality of field and sweet corn, often resulting in a product that does not meet food or feed safety requirements. Because it is a known carcinogen, contamination by aflatoxin reduces the marketability of corn both domestically and internationally. The difficulty of producing an aflatoxin-free crop has contributed to a reduction in corn acreage in the
southern U.S. Limited crop rotation options for growers impact the control of diseases and nematodes in other crops. Pearl millet has been proven to be a good poultry feed ingredient due to its nutritional quality and minimal processing cost. The chinch bug and the false chinch bug cause significant damage and loss of seedling stands of this new cover crop in Georgia and other southeastern states of the U.S. The goals of this project are to further the understanding of the mechanisms of resistance to insect damage and aflatoxin contamination in maize and pearl millet and to develop innate genetic resistance in regionally-adapted corn germplasm and inbreds to reduce losses from corn earworm, fall armyworm, and maize weevil feeding, and aflatoxin contamination. Successful completion of this research will result in the release of germplasm and inbreds with innate (non-transgenic) host resistance to both insect feeding and aflatoxin contamination and will improve regional grain
production. 2. List the milestones (indicators of progress) from your Project Plan. Since a project plan was not in place for this project from 2001 until July, 2005 due to an SY retirement and SY vacancies, there were no milestones for 2001-2005. 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. There were no milestones for 2005. Milestone Not Met Other 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? The project will expire in FY2005. 4a What was the single most significant accomplishment this past year? The most significant accomplishment this past year was the identification of appropriate methodologies for inoculation of corn with Aspergillus flavus. A method has been identified that allows for efficient and
practical screening of maize germplasm. 4b List other significant accomplishments, if any. Germplasm with resistance to both the Corn earworm and maize weevil has been identified. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Release of three populations with high maysin (SIM, EPM, and ZC2451F) that have increased resistance to the corn earworm, fall armyworm, and other Lepidoptera pests. These populations can be used as non-transgenic sources of resistance to Lepidoptera pests, which could be useful to non- traditional sectors of the agricultural arena, such as organic production. While no project plan was is place, this accomplishment meets the overall goal of this project to release germplasm with innate resistance to insects. 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? Three high-maysin maize populations were publicly released, transferring these technologies to other scientists in the public and private sectors. It is unknown if or when the technology will become available to the end user (the farmer) since private companies do not release information concerning the use of publicly-available germplasm in their breeding programs. A constraint to the adoption of these technologies is the time and resources required to incorporate the high-maysin traits into the breeding germplasm used by the companies.
Impacts
(N/A)
Publications
- Ni, X., Krakowsky, M.D. 2004. Insect screening results: evaluation of corn hybrids for resistance to insects. Corn Performance Tests. In Coy, A.E., Day, J.L., Rose, P.A. Georgia Agricultural Experiment Stations Research Report #696. p. 34-37.
- Ni, X., Mullis, J.C. 2004. Evaluation of grain sorghum hybrids for resistance to the sorghum midge. Georgia 2004 Soybean, Sorghum Grain and Silage, and Summer Annual Forages Performance Tests. Georgia Agricultural Experiment Station Research Report #697. pp. 44-45.
- Krakowsky, M.D., Lee, M., Coors, J.G. 2005. Quantitative trait loci for cell wall components in recombinant inbred lines of maize (Zea mays L.) I: stalk tissue. Journal of Theoretical and Applied Genetics. 111:337-346.
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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? The corn crop in the southeastern U.S. often suffers serious losses due to insect feeding on ears and leaves and contamination of the grain with aflatoxin, a carcinogenic mycotoxin produced by Aspergillus flavus. The losses associated with insect damage to the ears exacerbate the infection of the grain by A. flavus and increase subsequent contamination by aflatoxin. The chronic problems of insect damage and aflatoxin contamination drastically reduce the quality of field and sweet corn, often resulting in a product that does not meet food or feed safety requirements. The difficulty of producing an aflatoxin-free crop has contributed to a reduction in corn acreage in the southern U.S. Limited crop rotation options for growers impact the control of diseases and nematodes in other crops. Because it is a
known carcinogen, contamination by aflatoxin reduces the marketability of corn both domestically and internationally. Pearl millet has been proven to be a good poultry feed ingredient due to its nutritional quality and minimal processing cost. The chinch bug and the false chinch bug cause significant damage and loss of seedling stands of this new cover crop in Georgia and other southeastern states of the U.S. The goals of this project are to further the understanding of the mechanisms of resistance to insect damage and aflatoxin contamination in maize and pearl millet and to develop innate genetic resistance in regionally-adapted corn germplasm and inbreds to reduce losses from corn earworm, fall armyworm, and maize weevil feeding, and aflatoxin contamination. Successful completion of this research will result in the release of germplasm and inbreds with innate (non-transgenic) host resistance to both insect feeding and aflatoxin contamination and will improve regional grain
production. 2. List the milestones (indicators of progress) from your Project Plan. The major milestones of this project include publications of evaluations of maize germplasm for heterotic pattern and resistance to aflatoxin contamination and insect damage, effectiveness of methods of inoculation with A. flavus, genetic effects associated with resistance to aflatoxin contamination, selection of maize germplasm with multiple stressor resistance, and physical and biochemical traits and physiological markers for resistance to insects in maize and pearl millet, as well release of maize germplasm, and inbred lines with resistance to insect damage and aflatoxin contamination. 3. Milestones: 3.A. 2004 Milestones/Progress No milestones were met this year because the two SY on this project started within the last year and both positions had been vacant for at least one year prior and no project plan was in place. 3.B. 2005, 2006, and 2007 Milestones In 2005 we expect to publish results of a
study of the physical and chemical traits for fall armyworm resistance in maize foliage. In 2006 we expect to publish results of studies on a) mechanisms of corn earworm resistance in selected maize germplasm, b) biochemical markers for insect resistance in maize and pearl millet, c) physiological markers for insect resistance in maize and pearl millet, d) insect herbivory-aflatoxin contamination interactions, and e) selection of corn germplasm for multiple stressor resistance. In 2007 we expect to publish results of studies on a) Evaluation of exotic germplasm for heterotic pattern, b) germplasm with resistance to A. flavus / aflatoxin, c) A. flavus inoculation methods, and d) physical and chemical traits for fall armyworm resistance in maize foliage. 4. What were the most significant accomplishments this past year? There were no significant accomplishments for this project this year because the two SY on this project started within the last year and both positions had been vacant
for at least one year prior and no project plan was in place. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. There were no major accomplishments over the life of this project as no project plan is in place. A new project plan has been submitted this year. 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? No science and/or technology was transferred.
Impacts
(N/A)
Publications
- Widstrom, N.W., Butron, A., Guo, B.Z., Wilson, D.M., Snook, M.E., Cleveland, T.E., Lynch, R.E. Control of preharvest aflatoxin contamination in maize through pyramiding QTL involved in resistance to ear-feeding insects and invasion by Aspergillus sp. European Journal of Agronomy. 2003. v. 19. p. 563-572.
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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? The corn crop in the southeastern U.S. often sustains serious losses due to insect feeding on ears and leaves and to contamination of the grain with aflatoxin, a carcinogenic mycotoxin produced primarily by Aspergillus flavus. The losses are associated in that damage to the ear exacerbates infection of the grain by A. flavus and increases subsequent contamination by aflatoxin. The chronic problems of insect damage and aflatoxin contamination drastically reduce the quality of field and sweet corn, and often result in a product that is unusable. The goal of this project is to develop genetic resistance in regionally adapted corn germplasm and inbreds to reduce losses from corn earworm and fall armyworm feeding, and aflatoxin contamination. Resistance to the insects has been identified and is being transferred into elite sweet corn inbreds. Efforts to pyramid genes for resistance to corn
earworm and aflatoxin contamination into inbreds are in progress. Successful completion of this research has the potential for reducing pesticide usage on sweet corn by an estimated 75 to 80%, will result in the release of germplasm and inbreds with resistance to both insect feeding and aflatoxin contamination, and will improve regional grain production. 2. How serious is the problem? Why does it matter? Because of the pattern of insect feeding in the ear, preventing damage by corn earworm in the sweet corn crop now requires frequent applications of insecticides (from 20 to 40 applications are commonly required) during the period of development until harvest. The cost to growers and the potential impact to the environment are obvious. The difficulty of producing an aflatoxin-free crop has contributed to a reduction in corn acreage in the southern U.S. Limited crop rotation options for growers impacts the control of diseases and nematodes in other crops. Because it is a known
carcinogen, contamination by aflatoxin reduces the marketability of corn both domestically and internationally. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? This research supports National Program 301 (Plant, Microbial, and Insect Resistance, Genomics, and Genetic Improvement I.). Within NP 301, this research supports components "Genetic resource management", and "Genomic characterization and genetic improvement". Although not specifically coded as such, this research also supports National Program 108 (Food Safety) component "Mycotoxins", and National Program 303 (Plant Diseases) component "Host plant resistance to disease". 4. What were the most significant accomplishments this past year? A. The single most important accomplishment during FY 2003: Statewide (Georgia) field-testing of high-maysin maize germplasm was conducted to assess the relationship between husk tightness and silk- based insect resistance. Tight
husks were found to be essential to the success of silk-based insect resistance. The outcome of this work was to begin a backcross breeding program to introduce tight husks into germplasm with high maysin, resistance to A. flavus, and drought conditions. B. Other Significant Accomplishment(s), if any. None C. Significant Activities that Support Special Target Populations. None D. Progress Report None 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Several cDNA fragments and RFLP markers have been identified that are associated with genes that control maysin concentration in silks and resistance to infection by A. flavus and contamination by aflatoxin. PCR- based markers are being prepared for use in marker-assisted selection, and transfer of the resistance genes to elite germplasm. The final increases of four high maysin sweet corn inbred were made for the production of high maysin hybrids. Resistance genes
controlling the production of maysin, apimaysin, 3' - methoxy-maysin, isoorientin and rhamhnosyl isoorientin have been identified using molecular techniques, conventional quantitative procedures and translocation techniques making possible the use of these compounds for transfer into silks of breeding material. The use of an efficient and less expensive technique for initial screening genotypes for resistance to A. flavus infection and aflatoxin production is now available to reduce the overall cost of the screening process, by use of a color mutant of A. parasiticus that causes a reddish stain in the aleurone layer of the corn kernel when infected. Numerous germplasm releases with resistance to corn and sorghum insects have been made over the years, resulting in hundreds of requests by seed companies and research scientists at state universities, USDA laboratories, and foreign research institutions for the germplasm. 6. What do you expect to accomplish, year by year, over the next 3
years? FY2004: Import and characterize early tropical and subtropical germplasm from CIMMYT for combining ability, regional adaptation, and resistance to insect pests and aflatoxin contamination. FY2005: Conduct collaborative multlocation evaluations of germplasm selected for regional adaptation, and with resistance to insects and aflatoxin contamination. FY 2006: Conduct collaborative studies for locating markers linked to genes associated with agronomic traits, and resistance to insects and aflatoxin contamination. 7. 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? Numerous requests for seed of germplasm releases have filled at the local, national, an international levels. Most of the requests are bing made by public and private plant breeders for
introgression into their breeding programs. Corn performance data on commercially grown hybrids was published and distributed in a University of Georgia Bulletin. These data are used primarily to assist growers in making decisions about which hybrids they will grow in the following year. Georgia corn fields were surveyed for contamination with aflatoxin to assess progress in reducing losses due to toxigenic fungi. Publicity received as a result of registering two high maysin populations in Crop Science and publication of associated articles in several trade journals has resulted in an unusual number of requests for additional information and seed of those populations. Many requests have come from state and federal scientists and breeders, but most have been received from commercial seed companies. The four sweet corn inbreds, into which maysin had been transferred into their silks, were released to Syngenta under the conditions outlined in the CRADA with that seed company.
Impacts
(N/A)
Publications
- Widstrom, N.W., Butron, A., Guo, B.Z., Wilson, D.M., Snook, M.E., Cleveland, T.E., Lynch, R.E. Control of preharvest aflatoxin contamination in maize through pyramiding QTL involved in resistance to ear-feeding insects and invasion by Aspergillus sp. European Journal of Agronomy. 2003. v. 19. p. 563-572.
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Progress 10/01/01 to 09/30/02
Outputs
1. What major problem or issue is being resolved and how are you resolving it? The corn crop in the Southeastern U. S. often sustains serious losses due to ear and leaf-feeding insects and to contamination of the grain with aflatoxin, a carcinogenic mycotoxin produced by several Aspergillus spp. of fungi. The losses are associated with one another in that damage to the ear exacerbates infection of the preharvest crop by A. flavus and A. paraciticus, and increases subsequent contamination by aflatoxin. Improving resistance of the host plant is being accomplished through selection for reduced ear damage by insects and selection for reduced ear infection by Aspergillus spp. and contamination by aflatoxin. The chronic problems of insect damage and aflatoxin contamination drastically reduce grain quality and often result in a product that is unusable. Sweet corn for both the fresh and processed sweet corn markets is extensively sprayed with pesticides to eliminate
insect damage. Resistance to the corn earworm, the major insect pest of sweet corn in the Southeast, has been identified and demonstrated as transferable to elite sweet corn inbreds. Efforts to pyramid genes for resistance to corn earworm and aflatoxin contamination into single inbred sources are now in progress. Successful completion of this research has the potential for reducing pesticide usage on sweet corn by an estimated 75-80%. 2. How serious is the problem? Why does it matter? The prevention of damage by corn earworm to the sweet corn crop now requires sustained applications of insecticides (a range of 20-40 applications are commonly required) during the period of development until harvest. The cost to the grower and endangerment to the environment due to pollution are quite obvious. Contamination by aflatoxin in corn grain has been documented as a cause for increased evidence of cancer in humans and animals, often resulting in death of pets and livestock when the
contaminated grain is ingested. The aflatoxin problem has been established as a worldwide health hazard. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? National Program: 301 Plant, Microbial and Insect Germplasm Conservation & Development, 100%, with Components: Germplasm Enhancement and Manipulation, allows research scientists to work with commercial plant breeders to transfer antibiotic resistance in silks to sweet corn inbreds and hybrids. The research also allows scientists to locate corn and sorghum germplasm that is resistant to insects and toxigenic fungi, improve it for release to public and private breeders, and develop and demonstrate ways to efficiently transfer that resistance to commercial hybrids. Research in this CRIS addresses Agency priorities of reduced usage of pesticides, improved food safety, and more sustainable agricultural production. 4. What was your most significant accomplishment this past
year? A. The single most important accomplishment during FY 2002: Research was initiated to combine resistance to corn earworm (silk maysin and husk tightness) with resistance to aflatoxin contamination (resistance to A. flavus infection and drought conditions) using molecular techniques in cooperation with Dr. B. Guo, Crop Protection and Management Research Unit, Tifton, GA. Genetic markers have been identified for silk-maysin, husk tightness and drought resistance. The outcome of this research is expected to provide germplasm with much reduced susceptibility to ear-feeding insects, infection by A. flavus and contamination by aflatoxin. B. Other significant accomplishments: None. C. Significant Activities that Support Special Target Populations: None. 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? Several cDNA fragments and RFLP markers have been identified that are associated with genes that control maysin
concentration in silks and resistance to infection by A. flavus and contamination by aflatoxin. PCR- based markers are being prepared for use in marker assisted selection, and transfer of the resistance genes to elite germplasm. The implications of the developed germplasm are the reduction of pesticide usage, a safer environment and safer food and feed. The final increases for four sweet corn inbreds were made, completing the transfer of antibiotic resistance to the silks of those inbreds which will be used for the production of high maysin hybrids. Resistance genes controlling the production of maysin, apimaysin, 3'-methoxy- maysin, isoorientin and rhamnosyl isoorientin have been identified using molecular techniques, conventional quantitative procedures and translocation techniques making possible the use of these compounds for transfer into silks of breeding material. The use of an efficient and less expensive technique for initial screening of genotypes for resistance to A.
favus infection and aflatoxin production is now available to reduce the overall cost of the screening process. The technique utilizes a color mutant of A. parasiticus that causes a reddish stain in the aleurone layer of the corn kernel when infected. Numerous germplasm releases with resistance to corn and sorghum insects have been made over the years, resulting in hundreds of requests by seed companies and research scientists at state universities, USDA laboratories, and foreign research institutions for the germplasm. 6. What do you expect to accomplish, year by year, over the next 3 years? Although the incumbent in this position will retire in FY2002, it is expected that the work on locating markers linked to genes that are associated with agronomic traits will be continued and marker assisted selection will be used to improve germplasm for resistance to insects and aflatoxin contamination. Tentatively, the development of an effective expert system will continue through
incorporation of economic parameters with subsequent testing in on-farm situations. The distribution of released germplasm will continue as requests are received. The yearly evaluation of the performance of presently used commercial corn hybrids for resistance to insects is expected to continue. Other accomplishments will depend on the development of the breeding program for a successor in this position. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What are the constraints, if known, to the adoption durability of the technology? Numerous requests for seed of germplasm releases were filled at the local, national and international levels. Most of the requests are being made by public and private plant breeders for introgression into their breeding programs. Corn performance data on commercially grown hybrids was published and distributed in a University of Georgia
Bulletin. These data are used primarily to assist growers in making decisions about which hybrids they will grow in the following year. Georgia corn fields were surveyed for contamination with aflatoxin. This service is provided to assess the need to reduce losses due to toxigenic fungi, and to determine the losses due to these fungi so that informed decisions can be made regarding the distribution of research funding within the unit and within the state departments at the university level. Publicity received as a result of registering two high-maysin populations in Crop Science and publication of associated articles in several trade journals has resulted in an unusual number of requests for additional information and seed of those populations. Many requests have come from state and federal scientists and breeders, but most have been received from commercial seed companies. The four sweet corn inbreds, into which maysin had been transferred into their silks, were released to
Syngenta under the conditions outlined in the CRADA with that seed company. 8. List your most important publications and presentations, and articles written about your work (NOTE: this does not replace your review publications which are listed below) Widstrom, N.W. High-maysin corn available for breeding. Agricultural Research. May 2002. p. 22.
Impacts
(N/A)
Publications
- Widstrom, N.W., Snook, M.E. Recurrent selection for maysin, a compound in maize silks, antibiotic to earworm. Plant Breeding. 2001. v. 120. p. 357- 359.
- Widstrom, N.W., Snook, M.E. Registration of EPM6 and SIM6 maize germplasm, high silk-maysin sources of resistance to corn earworm. Crop Science. 2001. v. 41. p. 2009-2010.
- Widstrom, N.W., Burton, G.W., Gates, R.N. Registration of high digestibility maize germplasm. Crop Science. 2001. v. 41. p. 2010.
- Widstrom, N.W., Snook, M.E., Guo, B.Z. Synthesis of chemical defenses in maize silks against corn earworm and their inheritance in the flavonoid pathway. Ananthakrishnan, T.N., editor. Science Publishers, Inc., Enfield, NH. Insects and Plant Defense Dynamics. 2001. p.55-69.
- Guo, B.Z., Zhang, Z.J., Butron, A., Widstrom, N.W., Snook, M.E., Lynch, R. E., Plaisted, D. Quantitative effects of loci pl and al on the concentrations of maysin apimaysin, ethoxymaysin, and chlorogenic acid in maize silk tissue. Maize Genetic Cooperative Newsletter. 2001. V. 75. p. 64-66.
- Widstrom, N.W., Rector, B.G. Evaluation of corn hybrids for resistance to insects. Coy, A.E., Day, J.L., Rose, P.A., editors. Georgia Agricultural Experiment Stations Research Report Number 675. Georgia 2001 Corn Performance Tests. 2001. p. 38-40.
- Guo, B.Z., Li, R.G., Widstrom, N.W., Lynch, R.E., Cleveland, T.E. Genetic variation within maize population GT-MAS:gk and the relationship with resistance to Aspergillus favus and aflatoxin production. Theoretical and Applied Genetics. 2001. v. 103. p. 533-539.
- Butron, A., Widstrom, N.W. Mass selection for agronomic performance and resistance to ear-feeding insects in three corn populations. Maydica. 2001. v. 46. p. 2097-2012.
- Guo, B.Z., Butron, A., Li, H., Widstrom, N.W., Lynch, R.E. Restriction fragment length polymorphism assessment of the heterogeneous nature of maize population GT-MAS:gk and field evaluation of resistance to aflatoxin production by Aspergillus favus. Journal of Food Protection. 2002. v. 65. p. 167-171.
- Butron, A., Li, R.G., Guo, B.Z., Widstrom, N.W., Snook, M.E., Cleveland, T. E., Lynch, R.E. Molecular markers to increase corn earworm resistance in a maize population. Maydica. 2001. v. 46. p. 117-124.
- Butron, A., Widstrom, N.W., Snook, M.E., Wiseman, B.R. Recurrent selection for corn earworm (Lepidoptera:Noctuidae) resistance in three closely related corn southern synthetics. Journal of Economic Entomology. 2001. v. 95. p. 458-462.
- Mubatanhema, W., Wilson, D.M., Widstrom, N.W., Holbrook, C.C. A simplified method for field and research screening of aflatoxin in corn and peanut. Proceedings of 14th Aflatoxin Elimination Workshop. 2001. Phoenix, Arizona. p. 95.
- Guo, B.Z., Widstrom, N.W., Holbrook, C.C., Lee, R.D.,Coy, A.E., Lynch, R.E. Molecular genetic analysis of resistance mechanisms to aflatoxin formation in corn and peanut. Proceedings of 14th Aflatoxin Elimination Workshop. 2001. Phoenix, Arizona. p. 118.
- Guo, B.Z., Xu, G., Cao, Y.G., Widstrom, N.W., Lynch, R.E. RFLP markers associated with silk antibiosis and PCR-based markers for marker-assisted selection. Proceedings of 14th Aflatoxin Elimination Workshop. 2001. Phoenix, Arizona. p. 132.
- Butron, A., Li, H., Guo, B.Z., Widstrom, N.W., Lynch, R.E. RFLP assessment on heterogeneous nature of maize population GT-MAS:gk and field evaluation of resistance to aflatoxin production by Aspergillus flavus. Proceedings of 14th Aflatoxin Elimination Workshop. 2001. Phoenix, Arizona. p. 131.
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