Progress 09/15/01 to 09/14/04
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? Diseases incited by viruses, bacteria, and fungi cause serious losses to production of vegetable crops. This new project was established April 25, 2003 to develop effective, biologically-based management practices that do not rely on conventional pesticides to control these diseases. The objectives of research under this project are to: 1) elucidate etiology and epidemiology of major diseases of vegetable crops caused by viruses and other pathogens to identify vulnerable areas that provide biologically-based control opportunities, 2) utilize one or more biologically-based control method such as host resistance, use of antagonistic organisms, or elimination of pathogen reservoirs to develop new and effective management practices against targeted diseases, and 3) identify sources of genetic disease and/or
vector resistance and facilitate the incorporation of this resistance into enhanced germplasm or new varieties of vegetable crops. The project to be undertaken falls under National Program 303 - Plant Diseases, with National Program Components: II, Biological Control; IV, Pathogen Biology, Genetics, Population Dynamics, Spread, and Relationship with Hosts and Vectors; and V, Host Plant Resistance to Disease. New and effective control measures are greatly needed against viral, bacterial, and fungal diseases, because these diseases of vegetable crops are major production limiting factors. For many vegetable crop diseases there are no known control methods that are both effective and economically feasible. For many other diseases, effective current control methods rely on conventional pesticides which are being withdrawn. Biologically-based, more environmentally-compatible strategies are greatly needed to provide effective controls that are economically feasible, environmentally
compatible, and acceptable to consumers. Such control methods are critical to ensuring a continued, affordable, safe supply of nutritious vegetable crops. 2. List the milestones (indicators of progress) from your Project Plan. This is a new project. The Project Plans and Milestones have yet to be established. 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 an effective seed treatment method for Pepino mosaic virus on tomato seeds. Milestone Fully Met 2. Sequence the virus genome and develop an infectious transcript Milestone Fully Met 3. Develop transgenic plants (Nicotiana benthamiana and tomato) that express the coat protein gene of Pepino mosaic virus and evaluate disease resistance under greenhouse conditions. Milestone Not Met Redirection of Research focus due to change in priorities 4. Survey and characterize Ralstonia solanacearum, the causal
agent of bacterial wilt of tomato. 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? Year 1 (FY 2006) Survey and characterize prevalent strains of viruses and bacteria on vegetable crops. Work with plant breeders to develop efficient disease resistant screening protocols and perform preliminary screenings of germplasm collections, breeding lines, and cultivars. Develop Real-time PCR and microarray-based pathogen identification system for vegetable pathogens. Establish a global gene expression study of bacterial biofilm formation and colonization of plant roots. Year 2 (FY 2007) Expand Real-time PCR and microarray-based detection method to wide range of vegetable pathogens and for study of pathogen population change and strain shift. Generate and identify molecular markers for resistant genes to facilitate breeding
process through marker-assisted breeding programs. Initiate a survey for biological (bacterial and fungal) agents with control potential of bacterial diseases of crucifers. Year 3 (FY 2008) Continue molecular marker study for resistant genes to facilitate breeding process through marker-assisted breeding programs. Develop map-based cloning system to initiate mapping and cloning of the identified resistant genes. Initiate Bio-based control field trials of peppery leaf spot and black rot pathogens. 4a What was the single most significant accomplishment this past year? Researchers under this project have successfully characterized the viral geneome sequence of two new isolates of PepMV, an emergent virus of tomato, and its mode of transmission. These findings are important because the newly discovered information will facilitate studies on the evolution of the virus and the development of effective treatments. The understanding that PepMV is seed borne but not seed transmitted on tomato
seeds will allow the development of an effective seed treatment method. In fact a hot water soaking of tomato seed was effective to deactivate the virus infectivity with no adverse effect on seed germination. Understanding of the virus genome sequence allowed us to develop highly sensitive Real-time RT-PCR technique for detection of PepMV in various tissues, including leaf, fruit and seed. 4d Progress report. This report documents research funded by an Initiative for Future Agriculture and Food Systems grant and conducted through a reimbursable agreement between ARS and Cornell University. Research is conducted under the parent project 6659-22000-013-00D Identification, Elucidation, and Use of Disease and Nematode Resistances in Vegetable Crops under which additional information can be found. The N gene and the Me genes have been reported to control resistance to root-knot nematodes in pepper, Capsicum annuum. Although each gene system has been individually well characterized,
resistance controlled by the two genetic systems has not been compared in a single study. We characterized resistance to M. incognita race 3 in pepper genotypes carrying the N or Me genes. Twelve pepper genotypes that differ in the presence or absence of the N and Me genes were evaluated in this test. All four genotypes (PA-426, Carolina Cayenne, Charleston Belle, and Carolina Wonder) that carry the N gene (or alleles of the N gene) exhibited high resistance to M. incognita. Two genotypes HDA 149 and PM 687 that carry the Me3 and Me4 genes exhibited high resistance, similar to resistance of PM 217 that carries Me1 and Me2. HDA 330, which carries the Me1 gene, exhibited low resistance to M. incognita. These results are interesting because there appears to be a range of reactions to M. incognita among the root-knot nematode resistant genotypes tested; this information will aid in elucidating resistance conferred by the N and Me genes. All four of the susceptible check cultivars
(California Wonder, Yolo Wonder B, Keystone Resistant Giant, and PA-350) were susceptible to M. incognita, as expected. Seed of HDA 149, HDA 330, PM 217, and PM 687 was provided for these studies by Prof. Allain Palloix, Centre de Recherche Agronomique dAvignon, INRA, France. In efforts to identify genetic markers linked to the N gene in pepper, 234 polymorphic AFLP markers were identified as present in the root-knot nematode resistant cultivars Mississippi Nemaheart and Carolina Wonder (both carrying the N gene), but absent in susceptible Yolo Wonder B. The development of high-throughput molecular markers linked to the N gene would allow breeders to use marker- assisted selection (MAS) to rapidly develop root-knot nematode resistant genotypes. This project relates to Objective 1, Characterize and develop improved resistances to root-knot nematodes and diseases in vegetable crops including pepper, southernpea, sweetpotato, and watermelon, of the parent CRIS project 6659-22000-013.
5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. This is a new project. The major accomplishments were the identification and characterization of an emerging virus on tomato (Pepino mosaic virus), the molecular detection technique development and disease management through seed treatment technology. The future application of the seed treatment technology should enable seed companies to sell proper-treated tomato seeds and to protect U. S. tomato industry from potential economic loss incurred by this devastating disease. 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? None to report. New project. 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). Ling, K. S. 2005. High sequence homology between Pepino mosaic virus isolates from Chile and the USA. International working groups on legume and vegetable viruses, April 10-14, 2005, Ft. Lauderdale, FL. (ARS Log #172904) (also above Abstract appears on-line http://www.ifa.to.cnr. it/vvwg/documents/Abstracts_Rev.pdf). p20 Ling, K. S. 2005. Real-time immunocapture RT-PCR detection of Pepino mosaic virus on tomato seed and plant tissues in a single tube. Annual meeting of the American Phytopathological Society, Austin, TX, July 30- August 3, 2005. (ARS 115 Log #179098) Wechter, W.P. and Kluepfel, D.A. 2005 Global gene expression of Pseudomonas putida KT2440 during growth in the rhizosphere of Arabidopsis thaliana. Annual meeting of the American Phytopathological Society, Austin, TX, July 30-August 3, 2005. (ARS 115 Log #178993) Levi, A., Wechter, W.P., Davis, A.R., and
Alvaro, H. 2005. Constructing cDNA libraries and developing ESTs for watermelon fruit. Proceedings of the Workshop on Cucurbit Genomics Barcelona, Spain June 30 2005. (ARS 115 Log #183343)
Impacts
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Publications
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