Instability of the Magnaporthe oryzae avirulence gene AVR-Pita alters virulence.
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.
Zhou
Erxun
E
Department of Plant Pathology, South China Agricultural University, Guangzhou, Guangdong, PR China.
Jia
Yulin
Y
Singh
Pratibha
P
Correll
James C
JC
Lee
Fleet N
FN
D000595:Amino Acid Sequence; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics; D005800:Genes, Fungal; D017343:Genes, Plant; D042822:Genomic Instability / Q000235:genetics*; D020082:Magnaporthe / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D014774:Virulence / Q000235:genetics
D004251:DNA Transposable Elements; C413574:Pi-ta protein, Oryza sativa; D010940:Plant Proteins; D018160:Receptors, Cytoplasmic and Nuclear