Location: Foreign Disease-weed Science Research2010 Annual Report
1a. Objectives (from AD-416)
The objectives of the project are: 1) test U.S. wheat cultivars for resistance to the wheat blast pathogen, Magnaporthe grisea; 2) characterize wheat blast resistance; and 3) develop tools for the rapid detection of M. grisea. This project will enhance research in Project 1920-220000-035-00D, under Sub-objectives 1.A “ Develop accurate and rapid means for identification and detection”, 2.B “Elucidate the range of potential hosts for foreign plant pathogens”, 2.C “Evaluate environmental parameters on the initiation, establishment and progression of disease”, and 3” Screen germplasm for resistant sources to emerging and foreign fungal plant pathogens”.
1b. Approach (from AD-416)
A nursery of U.S. commercial wheat cultivars will be established at the Foreign Disease-Weed Science Research Unit. Plants in the vegetative stage will be inoculated with conidia of M. grisea and subsequent disease assessed 7 days after inoculation. A disease rating scale has already been established. Each cultivar will be tested with a minimum of 5 geographically distinct isolates of M. grisea from Mato Grosso do Sul and Parana, Brazil, where the disease is a major problem. These trials will be repeated three times. Cultivars identified as resistant will be field tested in Brazil through a cooperator in Brazil.
3. Progress Report
Wheat blast, caused by Magnaporthe grisea, is a new and emerging a fungal disease in South America. Initially described in Brazil in 1986, it has spread to Bolivia, Paraguay, and most recently Argentina. This Reimbursable Agreement provides funding for travel and student assistance to support the research goals of the parent project. The project was monitored by the ADODR by direct participation in development of experimental protocols and execution of the studies, conference calls with Co-principal investigators at Kansas State University (KSU) and one site visit to KSU. A nursery of diverse wheat cultivars obtained from the USDA regional germplasm collections was establish on location and approximately 272 cultivars were screened in the containment greenhouse for resistance to foliar and spike infection using one isolate of wheat blast. Results from foliar infection were inconclusive and did not correlate to spike resistance. Though no cultivars were totally resistant to spike infection, 28 cultivars had less than 10% infection and are currently being retested. This work supports the parent project Milestone 3.A.2, months 36, 48 and 60, to assess U.S. wheat germplasm for wheat blast resistance. Separate experiments were conducted to determine the effect of dew period and conidial concentration on wheat infection. In addition, experiments to determine the effects of temperature and relative humidity on conidial survival were also conducted. These studies are relevant to parent program plan milestone 2.C.3, months 36 and 48, “If introduced, wheat blast could become established in the wheat growing areas of the U.S.” A meeting was held in Florida attended by a scientist from ARS, The Brazilian Agricultural Research Corporation (EMBRAPA), the International Maize and Wheat Improvement Center, Mexico and University of Gottingen, Germany, to plan for an international workshop on wheat blast. In May,2010, the 1st International Workshop- “Wheat Blast a Potential Global Threat to Wheat Production”, was held in Passo Fundo, Brazil resulting in a proposal to establish an international wheat blast consortium to facilitate the exchange of isolates, establishment of nurseries for germplasm testing in Brazil and Bolivia, and applying for international research funding to address the identified research priorities. Contacts were made to obtain isolates from Bolivia, Paraguay, Argentina, and Brazil. A second meeting was held in Brasilia with EMBRAPA administrators and attorneys to discuss procedures for working within Brazil’s Biodiversity laws, which have prevented us from obtaining new field isolates of the disease.