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1. Instability of the Magnaporthe oryzae avirulence gene AVR-Pita alters virulence

Description:
The avirulence gene AVR-Pita of Magnaporthe oryzae determines the efficacy of the resistance gene Pi-ta in rice. The structures of the AVR-Pita alleles in 39 US isolates of M. oryzae were analyzed using polymerase chain reaction. A series of allele-specific primers were developed from the AVR-Pita gene to examine the presence of AVR-Pita. Orthologous alleles of the AVR-Pita gene were amplified from avirulent isolates. Sequence analysis of five alleles revealed three introns at identical positions in the AVR-Pita gene. All five alleles were predicted to encode metalloprotease proteins highly similar to the AVR-Pita protein. In contrast, the same regions of the AVR-Pita alleles were not amplified in the most virulent isolates, and significant variations of DNA sequence at the AVR-Pita allele were verified by Southern blot analysis. A Pot3 transposon was identified in the DNA region encoding the putative protease motif of the AVR-Pita protein from a field isolate B2 collected from a Pi-ta-containing cultivar Banks. These findings show that transposons can contribute to instability of AVR-Pita and is one molecular mechanism for defeating resistance genes in rice cultivar Banks.
Author:
Zhou, E.X. , Jia, Y.L. , Singh, P. , Correll, J.C. , Lee, F.N.
Subject:
Magnaporthe , plant pathogenic fungi , genes , virulence , alleles , introns , DNA primers , polymerase chain reaction , nucleotide sequences , transposons , pathogenicity , blast disease , Oryza sativa , rice
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Year:
2007

2. Rice Pi-ta gene confers resistance to the major pathotypes of the rice blast fungus in the United States

Description:
Includes references
Author:
Jia, Y. , Wang, Z. , Fjellstrom, R.G. , Moldenhauer, K.A.K. , Azam, M.A. , Correll, J. , Lee, F.N. , Xia, Y. , Rutger, J.N.
Subject:
Oryza sativa , rice , Magnaporthe grisea , plant pathogenic fungi , blast disease , pathogenicity , pathotypes , disease resistance , genes , cultivars , genetic variation , genetic markers , alleles , chromosome mapping
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Year:
2004