Resumen

GONZALEZ, Alex et al. Lineage diversity and virulence of a Venezuelan population of  Pyricularia oryzae, the cause of rice blast. Bioagro [online]. 2014, vol.26, n.1, pp.29-37. ISSN 1316-3361.

The main phytopathological problem of rice production in Venezuela is caused by fungus Pyricularia oryzae (= P. grisea), causal agent of rice blast. The pathogen populations have high variability which reduces the durability of resistant varieties and decreases the efficacy of specific fungicides. Given the level of importance of this disease, the objective of this study was to determine the diversity of lineages and virulence of a Venezuelan population of the fungus P. oryzae in order to use strains with large discriminatory power in the breeding programs for resistance to rice blast. Thus, 81 isolates from the fungus collection (2005 and 2006) and representatives of the six Venezuelan lineages were evaluated using the Pot2 molecular marker; and 45 isolates of the 2006 collection were inoculated on 26 rice cultivars. By calculating the Dice coefficient, isolates were grouped in 13 patterns, from which three are known lineages, and ten came out to be new lineages. No isolates were found for three previously reported lineages. Analysis of variance showed different virulence spectra in the behavior of isolated strains to the cultivars. A Procrustes analysis determined that both methods discriminate similarly (68 %), giving more than 70 % consensus between them, and showed the existence of a relationship between haplotypes and patotypes. We identified new lineages and strains with a broad virulence spectrum that can be used in later studies for purposes of blast resistance in rice.

Palabras clave : Pyricularia grisea; Oryza sativa; isolate; molecular marker.

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