ARS | Publication request: Natural variation of the rice blast resistance gene Pi-ta in Oryza species and its corresponding avirulence gene AVR-Pita in Magnaporthe oryzae

Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2006
Publication Date: January 13, 2007
Citation: Wang, X., Jia, Y., Correll, J., Lee, F.N., Wu, D., Shu, Q. 2007. Natural variation of the rice blast resistance gene Pi-ta in Oryza species and its corresponding avirulence gene AVR-Pita in Magnaporthe oryzae. Plant and Animal Genome Conference Proceedings.

Technical Abstract: The Pi-ta gene prevents the infections of M. oryzae races containing the corresponding avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta is a putative NBS type major resistance gene, and can directly recognize the AVR-Pita putative metalloprotease in triggering effective resistance. We have been investigating the natural variation of Pi-ta in 200 Oryza accessions, and AVR-Pita in M. oryzae isolates from USA, China and Colombia in an effort to infer the origin, distribution and evolution of both Pi-ta and AVR-Pita. To date, more nucleotide variations were observed in the intron region than in the coding regions of the Pi-ta alleles. In contrast, more nucleotide variations were observed in the coding regions than in the intron regions of the AVR-Pita alleles. These data suggest that the ratio of nonsynonymous substitution (Ka) to synonymous substitutions (Ks) is less than 1 for Pi-ta, and greater than 1 for AVR-Pita. Further sequence analysis of Pi-ta alleles in different Oryza species and AVR-Pita alleles in M. oryzae isolates will lead to insights on molecular dynamics of co-evolution between Pi-ta and AVR-Pita, and the results will be presented.