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.
Twenty-eight of 272 winter wheat cultivars previously shown in greenhouse inoculations to produce less than 10 percent infection to a single isolate of Magnaporthe oryzae (wheat blast) were retested and 21 cultivars still had less than 10% infection. Arrangements have been made to vernalize and field-test these cultivars at two sites in Bolivia and two sites in Paraguay this fall. Fifty-five spring barley cultivars were tested for blast resistance, and eight cultivars had less than 10 percent infection. These cultivars are being retested. A nursery of 222 spring wheat cultivars has been assembled for screening for blast resistance. Studies to determine the effect of dew period, temperature and conidial concentration on wheat infection are ongoing as greenhouse space permits. Studies to determine the rate of seed transmission and the efficacy of existing fungicidal seed treatments are underway.