Molecular screening of avirulence genes in field isolates of Magnaporthe oryzae from Argentina

LAURA E. GIARROCCO, V. FABIANA CONSOLO, AND GRACIELA L. SALERNO

Mar del Plata

Congreso; VIII Encuentro Latinoamericano y del Caribe de Biotecnología, REDBIO 2013; 2013

Blast disease caused by the hemibiotrophic Magnaporthe oryzae is one of the most severe threats to rice production in Argentine. Utilization of rice cultivars in which resistance is mounted by co-expression of a resistance ® bene in rice and its cognate avirulence (Avr) gene in M. oryzae has been applied as the most economical and efficient way to control this disease. In order to obtain a comprehensive understanding of the structural and fuctional variation in the M. oryzae Avr genes for some broad-spectrum blast-resistance genes, we analyzed a collection of 50 field isolates of the pathogen from major rice-producing areas of Argentine. Molecular characterization of four M. oryzae Avr genes were evaluated in previously characterized native isolates using Pot2-DNA fingerprinting. Results were compared to those of virulence assays on a set of differential rice cultivars and near isogenic lines bearin different Pi genes. Different haplotypes of Avr genes were detected in the sequenced alleles. Frequency of Avr genes in native M. oryzae and the corresponding Pi resistance previously analyzed by molecular markers in 64 rices varieties of Argentinean rice germplasm were registered. The results will be useful for breeding rice cultivars with durable blast resistence.