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ARS Home » Southeast Area » Stuttgart, Arkansas » Dale Bumpers National Rice Research Center » Research » Publications at this Location » Publication #287585
Title: Induction of avirulence in U.S. virulent field isolates of Magnaporthe oryzae by AVR-Pita 1

Author
item DAI, YUNTAO - University Of Arkansas
item Crowley, Eugenia
item CORRELL, JAMES - University Of Arkansas
item Jia, Yulin

Submitted to: Annual International Plant & Animal Genome Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/14/2012
Publication Date: 1/14/2014
Citation: Dai, Y., Crowley, E.W., Correll, J.C., Jia, Y. 2014. Induction of avirulence in U.S. virulent field isolates of Magnaporthe oryzae by AVR-Pita 1. Poster presentation for International Plant & Animal Genome XX/ January 14-18, 2012, San Diego, CA.

Interpretive Summary: The avirulence gene AVR-Pita1 in rice blast fungus Magnaporthe oryzae determines the stability of resistance mediated by the Pi-ta resistance gene. In the present study, the avirulence function of AVR-Pita1 was induced in field isolates (TM2, ZN19, B2 and B8) that originally were virulent on Pi-ta containing rice cultivars using homologous recombination. The presence of AVR-Pita1 in the independent recombinants was detected by PCR and verified by DNA sequencing and Southern blot analysis. We showed that the AVR-Pita1-recombinate isolates were not able to infect rice cultivars Katy and Drew possessing Pi-ta. In contrast, control isolates that were transformed with inserts lacking the AVR-Pita1 gene remained virulent. These findings should facilitate the development of effective strategies to prevent rice blast disease.

Technical Abstract: The AVR-Pita1 gene, from the Chinese isolate O-137 of Magnaporthe oryzae, is an effector that determines the efficacy of the Pi-ta rice blast resistance gene. In the present study, the avirulence function of AVR-Pita1 was induced in field isolates (TM2, ZN19, B2 and B8) that originally were virulent on Pi-ta containing rice cultivars using homologous recombination. The AVR-Pita1 gene, from the strain O-137, was introduced into the virulent field isolates TM2, ZN19, B2 and B8, by standard homologous recombination. The presence of AVR-Pita1 from O-137 in the independent recombinants was detected by PCR using AVR-Pita1 specific primers and verified by DNA sequencing and Southern blot analysis using the AVR-Pita1 coding region as the probe. Interestingly, the results from pathogenicity assays showed that the AVR-Pita1-recombinate isolates were not able to infect rice cultivars Katy and Drew possessing Pi-ta. Control isolates that were transformed with inserts lacking the AVR-Pita1 gene remained virulent. Our findings in this current study have implications on how the evolution of the fungal effector protein, AVR-Pita1 can be used for crop protection.