Sequencing and Comparative Analysis of the Straw Mushroom (Volvariella volvacea) Genome

Abstract

Volvariella volvacea, the edible straw mushroom, is a highly nutritious food source that is widely cultivated on a commercial scale in many parts of Asia using agricultural wastes (rice straw, cotton wastes) as growth substrates. However, developments in V. volvacea cultivation have been limited due to a low biological efficiency (i.e. conversion of growth substrate to mushroom fruit bodies), sensitivity to low temperatures, and an unclear sexuality pattern that has restricted the breeding of improved strains. We have now sequenced the genome of V. volvacea and assembled it into 62 scaffolds with a total genome size of 35.7 megabases (Mb), containing 11,084 predicted gene models. Comparative analyses were performed with the model species in basidiomycete on mating type system, carbohydrate active enzymes, and fungal oxidative lignin enzymes. We also studied transcriptional regulation of the response to low temperature (4°C). We found that the genome of V. volvacea has many genes that code for enzymes, which are involved in the degradation of cellulose, hemicellulose, and pectin. The molecular genetics of the mating type system in V. volvacea was also found to be similar to the bipolar system in basidiomycetes, suggesting that it is secondary homothallism. Sensitivity to low temperatures could be due to the lack of the initiation of the biosynthesis of unsaturated fatty acids, trehalose and glycogen biosyntheses in this mushroom. Genome sequencing of V. volvacea has improved our understanding of the biological characteristics related to the degradation of the cultivating compost consisting of agricultural waste, the sexual reproduction mechanism, and the sensitivity to low temperatures at the molecular level which in turn will enable us to increase the industrial production of this mushroom.

The Natural Histories of Species and Their Genomes

“…The mycelia of V. volvacea have no clamp connections. The species appears to be homothallic and capable of mating with itself (Bao et al, 2013).…”

“…The out-group Volvariella volvacea, an edible mushroom and decomposer of agricultural waste An extensive literature on V. volvacea focuses on its use as a crop (Bao et al, 2013;Chang, 1977;Date & Mizuno, 1997). The fungus is cultivated throughout Asia, and especially in China, where it has been grown since the eighteenth century.…”

The Accordant Trend of Both Parameters (rgs Expression and cAMP Content) Follows the Pattern of Development of Fruiting Body in Volvariella volvacea

“…The precise control of fruiting body formation may improve mushroom production, with consequent economic benefits. Recently, genome sequencing research [1,6] has improved our understanding of the development of V. volvacea. However, to our knowledge, the regulation of fruiting body formation in V. volvacea at a molecular level is still poorly understood.…”

Genome Mining for Fungal Secondary Metabolic Gene Clusters

“…Driven by an interest in fungi as sources for lingocellulose-degrading enzymes [26] and affordable next-generation sequencing technologies [27], the number of Basidiomycota genomes alone has ballooned from less than 5 a few years ago to currently over 100 draft genomes listed at the Joint Genome Institute's (JGI) MycoCosm genome portal (http://genome.jgi.doe.gov/ programs/fungi/index.jsf), of which only a select few have been annotated in detail [28][29][30][31][32][33][34][35][36]. About twice as many Ascomycota genome sequences are listed at this portal, and many more are deposited at the National Center for Biotechnology Information (NCBI).…”