Data_Sheet_1_MAT1-1-3, a Mating Type Gene in the Villosiclava virens, Is Required for Fruiting Bodies and Sclerotia Formation, Asexual Development and Pathogenicity.DOCX

Villosiclava virens is the prevalent causative pathogen of rice false smut, a destructive rice disease. Mating-type genes play a vital role in the evolution of mating systems in fungi. Some fungi have lost MAT1-1-3, one of the mating-type genes, during evolution, whereas others still retain MAT1-1-3. However, how MAT1-1-3 regulates the sexual development of heterothallic V. virens remains unknown. Here, we generated the MAT1-1-3 mutants, which exhibited defects in vegetative growth, stress response, pathogenicity, sclerotia formation and fruiting body maturation. An artificial outcrossing inoculation assay showed that the Δmat1-1-3 mutant was unable to produce sclerotia. Unexpectedly, the Δmat1-1-3 mutant could form immature fruiting bodies without mating on potato sucrose agar medium (PSA) compared with the wild-type strain, most likely by activating the truncated MAT1-2-1 transcription to regulate the sexual development. Moreover, RNA-seq data showed that knockout of MAT1-1-3 results in misregulation of a subset of genes involved in sexual development, MAPK signaling, cell wall integrity, autophagy, epigenetic modification, and transcriptional regulation. Collectively, this study reveals that MAT1-1-3 is required for asexual and sexual development, and pathogenicity of V. virens, thereby provides new insights into the function of mating-type genes in the fungi life cycle and infection process.

绿核菌（Villosiclava virens）是引发毁灭性水稻病害——稻曲病的优势致病病原菌。交配型基因（mating-type genes）在真菌交配系统的演化过程中发挥着至关重要的作用。部分真菌在演化过程中丢失了交配型基因之一的MAT1-1-3，而另一些真菌则仍保留该基因。然而，MAT1-1-3如何调控异宗配合绿核菌的有性发育，目前仍不清楚。本研究构建了MAT1-1-3基因敲除突变体，该突变体在营养生长、胁迫响应、致病性、菌核形成以及子实体成熟等方面均存在缺陷。人工异交接种实验结果显示，Δmat1-1-3突变体无法形成菌核。出乎意料的是，与野生型菌株相比，Δmat1-1-3突变体在马铃薯蔗糖琼脂培养基（PSA）上无需交配即可形成未成熟子实体，这一过程极有可能通过激活截短型MAT1-2-1的转录来调控有性发育。此外，RNA测序（RNA-seq）数据显示，敲除MAT1-1-3会导致一系列参与有性发育、丝裂原活化蛋白激酶（MAPK）信号通路、细胞壁完整性、自噬、表观遗传修饰以及转录调控的基因表达失调。综上，本研究证实MAT1-1-3对绿核菌的无性及有性发育与致病性均不可或缺，从而为揭示交配型基因在真菌生命周期及侵染过程中的功能提供了新的视角。