GENOMIC CHARACTERIZATION OF RICE GERMPLASM
Location: Dale Bumpers National Rice Research Center
Title: MOLECULAR COEVOLUTION OF RICE RESISTANCE GENE PI-TA AND THE CORRESPONDING MAGNAPORTHE GRISEA AVIRULANCE GENE AVR-PITA
Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2005
Publication Date: January 15, 2005
Citation: Jia, Y., Winston, E.M., Singh, P., Zhou, E., Wamishe, Y., Jia, M.H., Correll, J., Rutger, J.N. 2005. Molecular coevolution of rice resistance gene pi-ta and the corresponding Magnaporthe grisea avirulance gene avr-pita [abstract]. In: Plant and Animal Genome Conference Proceedings. p. 74.
Understanding the population biology of both resistance genes and avirulence genes of rice blast fungus will allow the development of strategies to control rice blast 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 directly inside the host cell, triggering effective defense response. A survey of rice germplasm (in different rice production regions) has identified rice cultivars containing four haplotypes of the Pi-ta allele, 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 US 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.