Rhizoctonia solani is a major fungal pathogen of rice (Oryza sativa L.) that causes great yield losses in all rice-growing regions of the world. Here we report the draft genome sequence of the rice sheath blight disease pathogen, R. solani AG1 IA, assembled using next-generation Illumina Genome Analyser sequencing technologies. The genome encodes a large and diverse set of secreted proteins, enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, which probably reflect an exclusive necrotrophic lifestyle. We find few repetitive elements, a closer relationship to Agaricomycotina among Basidiomycetes, and expand protein domains and families. Among the 25 candidate pathogen effectors identified according to their functionality and evolution, we validate 3 that trigger crop defence responses; hence we reveal the exclusive expression patterns of the pathogenic determinants during host infection.

Scytalidium auriculariicola is the causative pathogen of slippery scar disease in the cultivated cloud ear fungus, Auricularia polytricha. In the present study, the mitogenome of S. auriculariicola was sequenced and assembled by next-generation sequencing technology. The circular mitogenome is 96,857 bp long and contains 56 protein-coding genes, 2 ribosomal RNA genes, and 30 transfer RNA genes (tRNAs). The high frequency of A and T used in codons contributed to the high AT content (73.70%) of the S. auriculariicola mitogenome. Comparative analysis indicated that the base composition and the number of introns and protein-coding genes in the S. auriculariicola mitogenome varied from that of other Leotiomycetes mitogenomes, including a uniquely positive AT skew. Five distinct groups were found in the gene arrangements of Leotiomycetes. Phylogenetic analyses based on combined gene datasets (15 protein-coding genes) yielded well-supported (BPP = 1) topologies. A single-gene phylogenetic tree indicated that the nad4 gene may be useful as a molecular marker to analyze the phylogenetic relationships of Leotiomycetes species. This study is the first report on the mitochondrial genome of the genus Scytalidium, and it will contribute to our understanding of the population genetics and evolution of S. auriculariicola and related species.

The target pathogen Villosiclava virens (teleomorph: claviceps oryzae-sativae) was isolated from the infected rice, where it caused false smut. In our study, the forming processes of the chlamydospores, chlamydospore balls, conidiospores, and secondary conidiospores during the asexual reproduction were observed more precisely and in greater detail than previous descriptions. The microstructure of the infected rice kernel showed that the outer dense chlamydospores piled around the false smut balls grown on XBZ medium; moreover the sclerotia consisting of dense mycelium were found. The different morphology was observed across the different growing conditions. In addition, we observed the nuclear numbers of both the conidiospores and hyphae using 4',6-diamidino-2-phenylindole (DAPI) staining. Because the fungus has small chromosomes and the numbers were not previously known, we analyzed the electrophoretic karyotype using a pulsed field gel electrophoresis (PFGE) technique. The results showed that V. virens has at least 10 chromosomes ranging in size from 0.6 kb to 6 Mb. The V. virens genome size is estimated to be 23 Mb. Here, we report the morphological characteristics of the fungus and the process of asexual spores forming asexual propagules, along with the first analyze the molecular karyotype of V. virens. These results supply a foundation for further study of the pathogenicity and biology of this devastating pathogen.

Ganoderma is well known for its use in traditional Chinese medicine and is widely cultivated in China, Korea, and Japan. Increased temperatures associated with global warming are negatively influencing the growth and development of Ganoderma. Nitric oxide is reported to play an important role in alleviating fungal heat stress (HS). However, the transcriptional profiling of Ganoderma oregonense in response to HS, as well as the transcriptional response regulated by NO to cope with HS has not been reported. We used RNA-Seq technology to generate large-scale transcriptome data from G. oregonense mycelia subjected to HS (32 °C) and exposed to concentrations of exogenous NO. The results showed that heat shock proteins (HSPs), “probable stress-induced proteins”, and unigenes involved in “D-amino-acid oxidase activity” and “oxidoreductase activity” were significantly up-regulated in G. oregonense subjected to HS (P < 0.05). The significantly up-regulated HSPs, “monooxygenases”, “alcohol dehydrogenase”, and “FAD/NAD(P)-binding domain-containing proteins” (P < 0.05) regulated by exogenous NO may play important roles in the enhanced HS tolerance of G. oregonense. These results provide insights into the transcriptional response of G. oregonense to HS and the mechanism by which NO enhances the HS tolerance of fungi at the gene expression level.

Villosiclava virens (anamorph: Ustilaginoidea virens) was isolated from infected rice plants, where it caused false smut. Similar to other ascomycetes, the sexual compatibility of V. virens is controlled by the mating type (MAT) locus. In this study, we applied a PCRbased approach to screen mating type genes in the single asexual spore isolate. Our results showed that V. virens possesses the two master genes required for mating (MAT1-1-1 and MAT1-2-1), suggesting that this fungus is likely to be homothallic. Mating type primer pairs were developed to genotype the single ascospore isolates from different places in China. These analyses provided further evidence that V. virens is a homothallic species and suggest novel genetic mechanisms of sexual reproduction in V. virens.