Investigating the cell biology of plant infection by the rice blast fungus Magnaporthe oryzae

Rice blast disease, caused by the filamentous, ascomycete fungus, Magnaporthe oryzae, is one of the most important limiting factors in rice production. Infection starts when a three-celled conidium lands on the leaf surface, carried by wind or splash dispersal. To enter the rice leaf, the fungus forms a dome-shaped infection structure called an appressorium. The melanized appressorium develops a penetration peg, which differentiates into a narrow primary invasive hypha (IH) and subsequently into bulbous invasive hyphae that colonize the first host cell. Previous live-cell imaging studies have demonstrated that IH are surrounded by the extra-invasive hyphal membrane (EIHM), an invagination of the host plasma membrane, which bounds IH as they proliferate in epidermal rice cells.  We have generated a series of rice (cv. Kitaake) transgenic lines expressing green fluorescent protein (GFP)-labelled subcellular components, including the plasma membrane, endoplasmic reticulum (ER), Golgi, nuclei, F-actin, microtubules, early and late endosomes. Using these transgenic lines, we aim to characterize the temporal development of blast disease and create a spatial atlas of the major cellular changes associated with blast infection, in both compatible and incompatible interactions. We have shown that blast infection is associated with disintegration of the F-actin cytoskeleton. We have also classified major changes in membrane organization and integrity during invasive growth. We will report the major plant cellular changes that accompany host tissue colonization by M. oryzae.