Septin-Mediated Plant Cell Invasion by the Rice Blast Fungus, Magnaporthe oryzae

Abstract

Blasting Through The fungus that causes rice blast disease, Magnaporthe oryzae , can lead to devastating reductions in rice yields. M. oryzae enters the plant by developing specialized infection structures called appressoria. Appressoria generate enormous internal turgor pressure that somehow creates invasive forces that physically break the plant cuticle. Dagdas et al. (p. 1590 ) found that a toroidal (doughnut-shaped) filamentous actin network forms at the base of the appressorium at the precise point where the penetration peg, which ruptures the rice leaf cuticle, will emerge. This network is scaffolded by means of four septin guanosine triphosphatases, which form a dynamic ring structure that colocalizes with F-actin. The findings reveal how fungi translate extreme pressure into localized physical force.