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We isolated an MgATG1gene encoding a serine/threonine protein kinase from the rice blast fungusMagnaporthe grisea. In the ΔMgatg1mutant, in which the MgATG1gene had been deleted, autophagy was blocked; the mutant also showed fewer lipid droplets in its conidia, lower turgor pressure of the appressorium, and such defects in morphogenesis as delayed initiation and slower germination of conidia. As a result of lower turgor pressure of the appressorium, the ΔMgatg1mutant lost its ability to penetrate and infect the two host plants, namely, rice and barley. However, normal values of the parameters and infective abilities were restored on reintroducing an intact copy of the MgATG1gene into the mutant. Autophagy is thus necessary for turnover of organic matter during the formation of conidia and appressoria and for normal development and pathogenicity inM. grisea.

Rice ( Oryza sativa L.) is, on a global scale, one of the most important food crops. Although endophytic fungi and bacteria associated with rice have been investigated, little is known about the endophytic fungi of wild rice ( Oryza granulate ) in China. Here we studied the root endophytic mycobiota residing in roots of O. granulate by the use of an integrated approach consisting of microscopy, cultivation, ecological indices, and direct PCR. Microscopy confirmed the ubiquitousness of dark septate endophytes (DSEs) and sclerotium-like structures in root tissues. Isolations from 204 root segments from 15 wild rice plants yielded 58 isolates, for which 31 internal transcribed spacer (ITS)-based genotypes were recorded. The best BLAST match indicated that 34.5% of all taxa encountered may represent hitherto undescribed species. Most of the fungi were isolated with a very low frequency. Calculation of ecological indices and estimation of taxon accumulation curves indicated a high diversity of fungal species. A culture-independent approach was also performed to analyze the endophytic fungal community. Three individual clone libraries were constructed. Using a threshold of 90% similarity, 35 potentially different sequences (phylotypes) were found among 186 positive clones. Phylogenetic analysis showed that frequently detected clones were classified as Basidiomycota, and 60.2% of total analyzed clones were affiliated with unknown taxa. Exophiala , Cladophialophora , Harpophora , Periconia macrospinosa , and the Ceratobasidium / Rhizoctonia complex may act as potential DSE groups. A comparison of the fungal communities characterized by the two approaches demonstrated distinctive fungal groups, and only a few taxa overlapped. Our findings indicate a complex and rich endophytic fungal consortium in wild rice roots, thus offering a potential bioresource for establishing a novel model of plant-fungal mutualistic interactions.

The interaction between pathogens and their host plants is a ubiquitous process. Some plant fungal pathogens can form a specific infection structure, such as an appressorium, which is formed by the accumulation of a large amount of glycerin and thereby the creation of an extremely high intracellular turgor pressure, which allows the penetration peg of the appressorium to puncture the leaf cuticle of the host. Previous studies have shown that autophagy energizes the accumulation of pressure by appressoria, which induces its pathogenesis. Similar to other eukaryotic organisms, autophagy processes are highly conserved pathways that play important roles in filamentous fungal pathogenicity. This review aims to demonstrate how the autophagy process affects the pathogenicity of plant pathogens.