2007 Annual Report
1a.Objectives (from AD-416)
The long term goal of this project is to reduce losses in wheat and barley yield and quality caused by stripe, leaf, and stem rusts, and assure stable,sustainable wheat and barley production while protecting the environment. Over the next five years we will focus on the following objectives: 1)determine factors influencing epidemic development and host-pathogen interactions for rusts, including to identify and monitor emerging races of stripe rust on a national basis and to improve rust prediction and integrated control; 2)evaluate germplasm and breeding lines of wheat and barley for resistance to rusts,including to support breeding programs in developing cultivars with adequate and durable resistance and to identify new sources and genes of effective resistance to stripe rust; and 3)determine the genomic structure and functional genes of the stripe rust pathogen and molecular mechanisms of plant-pathogen interactions.
1b.Approach (from AD-416)
The prevalence, severity, and distribution of rusts will be monitored through disease surveys in commercial fields, monitoring nurseries, and experimental plots of wheat and barley, as well as wild grasses. Stripe rust races will be identified by testing rust samples on wheat and barley differential genotypes. Rust epidemics will be predicted based on environmental and cropping system factors. Geographic regions where stripe rust can over-winter and over-summer will be mapped by analyzing climatic and cropping data. Disease forecasting models will be developed for various epidemic regions by analyzing historical weather and disease data and tested with rust survey data. Fungicide tests will be conducted to identify new effective fungicides. Germplasms and breeding lines of wheat and barley will be evaluated in greenhouses with selected races and in field plots under natural infections of rusts to support breeding programs. New sources and genes of effective resistance to stripe rust will be identified through germplasm evaluation, genetic studies, and molecular mapping. Molecular markers for resistance genes will be developed using resistance gene analog, microsatellite, and other marker techniques. The genomic structure and functional genes of the stripe rust pathogen and molecular mechanisms of plant-pathogen interactions will be determined through constructing physical and functional gene maps. Fingerprinting and end-sequencing bacterial artificial chromosome (BAC) clones will be conducted to construct the physical map, which will be filled with functional genes identified from cDNA clones of the pathogen. Functional genes will be identified by comparing the sequences of full-length cDNA clones to genes in GenBank databases. Molecular markers will be developed using sequences of functional genes and BAC-ends for studying population structures of the stripe rust pathogen. Genes of wheat and the stripe rust pathogen involved in the plant-pathogen interactions will be identified. Formerly 5348-22000-010-00D (3/07).
This report serves to document research conducted under an International Science and Technology Center (ISTC) – ARS-Former Soviet Union Research Program project (Project Number: 5348-22000-007-01R; Project Title: Determination of epidemiological factors and control of fungal disease complex on cereal crops in russia using biotechnology and information technology). The project is collaborated with scientists in All-Russian Research Institute of Phytopathology in Moscow and other Russian institutes.
Initiated in 2002 and renewed in 2005, the project was supported with the US-former Soviet Union Program. The purpose of the program was to convert research of scientists in the Former Soviet Union countries previously involved in warfare development to civil research. The goal of this project is to develop and apply advanced biotechnology and information technology in disease management of cereal crops in Russia. The objectives of the project were to study genetic diversity of fungal pathogens and plant resistance in cereal crops, investigate emergency and development conditions of disease outbreaks on cereal crops in various regions of Russia under modern cultivation technologies and simulate epidemics, and develop effective disease forecasting systems and cereal crop disease control based on up-to-date information technologies. Disease monitoring and analyses of disease samples and historical disease data were conducted in the All-Russian Research Institute of Phytopathology and other Russian institutes. Species structures of major fungal pathogens and their importance, virulence structures of rust pathogens, and resistances of Russian cultivars were determined. Models for disease development and damage estimation were developed for stripe rust, leaf rust, powdery mildew, Fusarium head blight, and Septoria leaf and glume blotches. The new phase of the project has expanded from the European part of Russia to cover the major areas of cereal crops in the Asian part of Russia. The research revealed critical factors for these diseases, which are useful in designing effective control programs. As an ARS collaborator, my responsibilities included providing expertise in the project planning, problem solving, and overseeing the project. In 2007, we exchanged wheat germplasm and evaluated wheat genotypes that were selected from tests conducted in Russia in our experimental fields in Washington for stripe rust resistance. Since the resistant genotypes likely have genes different from those we have used in the US, they can be used to diversify resistance genes used in the US breeding programs. I reviewed the quarterly and annual reports of the project and submitted the reports in a timely manner. The objectives of the project scheduled for 2007 have been successfully accomplished.
1). Accurately predicted and monitored stripe rust in 2007. Accurate disease forecast is essential for timely management of the disease. In 2007, ARS scientists in Pullman, WA conducted long-term, mid-term, and short-term forecasts for stripe rust epidemics using the weather data, disease monitoring data, and cultivar resistance and send stripe rust alerts to growers as early as in March and throughout the growing season. As a result of the accurate forecasting, timely alerts, and advises for choosing resistant cultivars to plant and making decisions on whether or not to use fungicides, wheat growers implemented appropriate measures for stripe rust control, which prevented major yield losses for the hard red winter wheat growing regions in Washington and saved growers’ multimillion dollars by preventing unnecessary use of fungicides in many other regions. This research addresses NP303 (Plant Diseases) Component 2 (Biology, Ecology, Epidemiology, and spread of Plant Pathogens and Their Relationships with Hosts and Vectors), Problem Statement 2C: Population Dynamics, Spread, and Epidemiology of Pathogens.
2). Evaluated wheat and barley germplasms and breeding lines for resistance to stripe rust. For control of the rust diseases, it is critical to identify more resistant germplasms and to select resistant breeding lines of wheat and barley for resistance. In 2007, ARS scientists in Pullman, WA evaluated more than 17,000 wheat and barley entries for stripe rust resistance. From the evaluation studies, new germplasm and advanced breeding lines with stripe rust resistance were identified and new core collections of wheat and barley germplasms with resistance to stripe rust were established. These core germplasm collections can be used for identifying new genes for resistance to stripe rust. The data and information of stripe rust evaluation were provided to breeding programs that would lead to eliminating potential susceptible cultivars, and developing new cultivars with adequate resistance. This research addresses NP303 (Plant Diseases) Component Component 3 (Plant Disease Resistance), Problem Statement 3B: Disease Resistance in New Germplasm and Varieties.
3). Determined molecular mechanisms for Yr5-mediated race-specific resistance and basal defense to the stripe rust pathogen. Understanding plant–pathogen interactions is essential for effectively use of genetic resistance to control diseases like stripe rust. Yr5 represents a single R gene that confers all-stage resistance to all identified North American races of the wheat stripe rust pathogen. In a microarray study, ARS scientists in Pullman, WA used the Wheat GeneChip® to profile the changes occurring in two wheat isogenic lines that differed for the presence of the Yr5 gene after inoculation with the stripe rust pathogen. Numerous defense-related expressed genes that were important for R-gene-mediated race-specific resistance as well as basal defense were identified. Our data supported a model that links the pathogen recognition to the expression of plant defense responses. The results provide novel insights into the cellular mechanisms of wheat defense to an economically important pathogen, and the findings will be useful for the development of durable resistant cultivars. This research addresses NP303 (Plant Diseases) Component 3 (Plant Disease Resistance), Problem Statement 3A: Mechanisms of Plant Disease Resistance.
5.Significant Activities that Support Special Target Populations
Advises on disease control were provided to growers through seminars, field talks, on-farm visits, phone conversation, and e-mails, which directly benefit growers and field consulting companies, many of which have small farms and business.
|Number of non-peer reviewed presentations and proceedings||13|
|Number of newspaper articles and other presentations for non-science audiences||8|
Babcock, C., Chen, X., Crous, P.W., Dugan, F.M., Goates, B., Green, P.N. 2007. Plant germplasm centers and microbial culture collections: A users guide to key genetic resources for plant pathology. Plant Dis. 91:476-484.
Chen, X. 2007. Challenges and solutions for stripe rust control in the United States. Australian Journal of Agricultural Research 58:648-655.
Lin, F., Chen, X. 2007. Genetics and molecular mapping of genes for race-specific all-stage resistance and non-race specific high-temperature adult-plant resistance to stripe rust in spring wheat cultivar Alpowa. Theor. Appl. Genet. 114:1277-1287.
Ling, P., Meinan, W., Chen, X., Garland Campbell, K.A. 2007. Construction and characterization of a full-length cDNA library for the wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici). BMC Genomics 8:145.
Nirmala, J., Dahl, S., Steffenson, B., Kannangara, C.G., Von Wettstein, D., Chen, X., Kleinhofs, A. 2007. Proteolysis of the barley receptor-like protein kinase Rpg1 by a proteasome pathway is required for Rpg1 mediated stem rust resistance. PNAS 104:10276-10281.
Wan, A.M., Chen, X., He, Z.H. 2007. Wheat stripe rust in China. Australian Journal of Agricultural Research 58:605-619.
Yan, G.P., Chen, X. 2007. Molecular Mapping of the rps1.a Recessive Gene for Resistance to Stripe Rust in BBA 2890 Barley. Phytopathology 97:668-673.
Chen, X., Wood, D.A. 2006. Reduction of stripe rust severities on spring wheat by seed treatment with fungicides, 2005. F&N Tests 61:ST010.
Chen, X., Wood, D.A. 2006. Control of stripe rust of winter wheat with foliar fungicides, 2005. F&N Tests 61:CF023.
Chen, X., Wood, D.A. 2006. Control of stripe rust of spring barley with foliar fungicides, 2005. F&N Tests 61:CF024.
Chen, X., Wood, D.A. 2007. Control of stripe rust of winter wheat with foliar fungicides, 2006. Plant Disease Management Reports. 1:FC108.
Chen, X., Wood, D.A. 2007. Control of stripe rust of spring wheat with foliar fungicides, 2006. Plant Disease Management Reports. 1:FC109.
Chen, X., Wood, D.A. 2007. Fungicide seed treatments for reducing yield losses caused by stripe rust on spring barley, 2006. Plant Disease Management Reports 1:ST005.
Chen, X., Wood, D.A. 2007. Fungicide seed treatments for reducing yield losses caused by stripe rust on spring wheat, 2006. Plant Disease Management Reports. 1:ST006.
Chen, X., Wood, D.A. 2007. Fungicide seed treatments for reducing yield losses caused by stripe rust on winter wheat, 2006. Plant Disease Management Reports. 1:ST007.
Rossi, C., Cuesta-Marcos, A., Vales, I., Gomez-Pando, L., Orjeda, G., Wise, R.P., Sato, K., Hori, K., Capettini, F., Vivar, H., Chen, X., Hayes, P. 2006. Mapping multiple disease resistance genes using a barley mapping population evaluated in Peru, Mexico, and the USA. Molecular Breeding 18:355-366.