Abstract

CRUZ, Maria Fernanda A. et al. Molecular pattern and virulence of Pyricularia grisea isolates from wheat. Trop. plant pathol. [online]. 2009, vol.34, n.6, pp. 393-401. ISSN 1982-5676.  http://dx.doi.org/10.1590/S1982-56762009000600005.

The use of molecular tools and virulence evaluations of Pyricularia grisea, the causal agent of rice and wheat blast, has permitted identification of strains of the pathogen, especially those occurring in the rice crop. Microsatellites have already demonstrated efficiency to classify P. grisea isolates by genetic similarity groups. The objectives of this work were to characterize the genetic diversity of 18 isolates of P. griseacollected from wheat by applying 8 microsatellite primers; and to compare the molecular and virulence results of isolates, when inoculated in seedlings of 70 wheat genotypes. The most informative primer was PG 5 with 4 alleles. The primers MG 21 and PG 12 permitted separation of Py 5020 and Py 5038 in distinct groups, with less than 50% similarity in relation to others. The genetic similarity of isolates presented more than 75% similarity among them. In the virulence analysis, 15 out of 18 tested isolates showed more than 85% of similarity. The molecular pattern and virulence were similar for the isolates, except for Py 5002 isolate. The absence of resistance to all isolates confirms the need to seek new sources or better genetic combinations of wheat that are more resistant to disease.

Keywords : microsatellite markers; allele; plant disease resistance; rice blast.