GKK1032A 2, a secondary metabolite from Penicillium sp. IBWF-029-96, inhibits conidial germination in the rice blast fungus Magnaporthe oryzae

摘要

The rice blast fungus Magnaporthe oryzae is the most important pathogen on cultivated rice because of its economic relevance and destructiveness.1 Blast disease caused by this heterothallic ascomycete destroys about 10-30% rice yield every year.2 In order to infect and colonize the host plant Oryza sativa, conidia of the fungus attach to the leaf surface and germinate by sending out a germ tube. Induced by the hard hydrophobic surface, appressoria required for penetration differentiate. Within the specialized infection structure compatible solutes, for example, glycerol, accumulate.3 The solutes are retained within the cell by a melanin layer. As a consequence, water flows into the infection structure to generate turgor required for a mechanically penetration of the plant cuticle. As the functionality of the appressor-ium is an essential prerequisite for a successful infection of the host plant, the melanin layer is a pathogenicity factor in M. oryzae.