Virulence and molecular characterization of Magnaporthe grisea isolates from two upland rice cultivars in Brazil

• Published in: Phytopathology Vol. 95; no. 6
• Main Authors: Prabhu, A, Araujo, L G, da Silva, GB
• Format: Journal Article
• Language: English
• Published: 01-06-2005
• Subjects: Magnaporthe grisea; Oryza sativa
• ISSN: 0031-949X

The phenotypic and genetic diversity of the isolates of Magnaporthe grisea was studied, in a sample population collected from two upland rice cultivars Primavera and Maravilha, susceptible to rice blast in Brazil. Forty six isolates of M. grisea, from the cultivar Primavera and 31 from the cultivar Maravilha, were analyzed. The virulence pattern analysis showed that the isolates from Maravilha exhibited greater virulence than the isolates from Primavera, on 32 test genotypes as well as on twelve commercial rice cultivars. Furthermore, a majority of isolates exhibiting compatible reaction to Primavera were incompatible to Maravilha and vice versa. A high percentage of isolates virulent to genes Pi-1, Pi-2 e Pi-4b in the near isogenic lines of CO39 were pre-existent. A phenogram constructed from virulence phenotype data showed two main groups considering 70% similarity level, one constituted of only isolates from Primavera and the other with 83.6% of the isolates from Maravilha. Rep-PCR analysis of isolates using two primer sequences from Pot2 showed two distinct fingerprint groups (lineages). There was close correspondence between clusters based on rep-PCR and virulence data. The results further showed that the isolates of M. grisea were cultivar specific and had narrow phenotypic and genetic diversity.