Analysis of early stage of infection in rice Magnaporthe grisea interactions.

Abstract

The infection process of the rice blast fungus into rice plant passes the stage of attachment of the spore to the leaf surface, germination, the appresorium formation, and the infectious hyphae formation. We analyzed the response of rice against blast fungus by using mutants that are arrested at each stage of infection. The accumulation of H₂O₂ and the phytoalexin in the rice was not seen in mgb1 that germinates but does not form the appresorium, whereas the accumulation of H₂O₂ beneath the appresorium was seen in mst12 that form no penetration peg. Differential expression of genes as well as the generation of H₂O₂ and phytoalexins was observed at 2 hrs after inoculation of wild type strain, Guy11, in an R-gene dependent manner. These results indicated that rice recognizes signals from pathogen before appresorium formation and the initiation of invasion is critical for the phytoalexin generation.