ARS | Publication request: MOLECULAR CHARACTERIZATION OF MAGNAPORTHE GRISEA AVIRULENCE AVR-PITA ALLELES IN US PATHOTYPES

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2004
Publication Date: July 30, 2004
Citation: Winston, E.M., Singh, P., Correll, J., Jia, Y., Rutger, J.N. 2004. Molecular characterization of Magnaporthe grisea avirulence AVR-Pita alleles in US pathotypes. American Phytopathological Society Annual Meeting. Phytopathology. 94(6):47.

Technical Abstract: The Pi-ta gene in rice confers resistance to Magnaporthe grisea isolates containing the corresponding avirulence gene AVR-Pita. Maintaining durable Pi-ta-mediated resistance is challenging due to the high degree of pathogenic variability and genetic instability of M. grisea. Genetic mapping demonstrated that the M. grisea AVR-Pita gene is closely linked to the telometric region residing on chromosome 3. Evidence suggests that a blast race TM2 can delete allelic sequences from its genome, thereby infecting Pi-ta containing rice cultivars. The objective of this study was to determine the functionality of AVR-Pita alleles in isolates of M. grisea races found in the Southern United States. Utilizing gene specific primers, the native promoter and coding regions of the AVR-Pita gene were amplified from cDNA and genomic clones of the M. grisea wild-type isolates 0-137 and ZN61 (race IB-49), respectively. Fragments were directionally cloned into the vector pBluescript SK+. Clones were analyzed by restriction digestion and PCR amplification using AVR-Pita gene specific primers. Clones homologous to AVR-Pita genomic sequence were subsequently transformed into the race-shift isolate TM2. Complementation studies will be subsequently performed by inoculating the recombinant pathogen onto Pi-ta containing rice cultivars.