Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2004
Publication Date: 11/15/2004
Citation: Jia, Y., Winston, E.M., Singh, P., Zhou, E., Wamishe, Y., Jia, M.H., Correll, J. 2004. Molecular mechanisms of durable rice blast resistance [abstract]. In: Proceedings, 2nd International Rice Functional Genomics Conference, Tucson, Arizona. Abstract p. 72.
Technical Abstract: Durable resistance to the blast pathogen, Magnaporthe grisea, can be achieved by deploying a resistance gene that recognizes a virulence factor that is essential for the pathogen to cause disease. The Pi-ta gene in rice is effective in preventing the infection of M. grisea races containing the corresponding avirulence gene AVR-Pita. Pi-ta is a single copy gene located at the centromere of chromosome 12. Pi-ta encodes a predicted cytoplasmic protein with a centrally located nucleotide-binding site and a leucine rich domain at its carboxyl terminus. AVR-Pita is a metalloprotease located near the teleometric region of chromosome 3 of M. grisea. Pi-ta appears to recognize AVR-Pita inside the host cell triggering effective defense response. A survey of rice germplasm (in different rice production regions) has identified one resistant (Pi-ta) haplotype and three susceptible pi-ta haplotypes. Pi-ta confers resistance to the major US M. grisea pathotypes; the polymorphic regions of Pi-ta that distinguish resistant and susceptible alleles of Pi-ta were successfully used for the development of dominant and codominant markers for marker assisted Pi-ta incorporation. Survey of the pathogen population in the USA indicates that the deletion of the AVR-Pita allele in some "race-shift" isolates of M. grisea can defeat protection provided by Pi-ta. Race-shift isolates have been selected and recovered from the field. Whether such isolates can prevail and cause economic losses depends on the role of AVR-Pita in both pathogenesis and pathogen fitness in the environment. Progress on the development of molecular strategies to control rice blast disease will be presented.