Small ubiquitin-like modifiers (SUMOs) act as the modifiers that regulate several important eukaryotic cell events during sumoylation, but little is known about the functions of SUMO or sumoylation in filamentous entomopathogens. Here, we report the important roles of a single SUMO-encoding gene, smt3, in Beauveria bassiana, a filamentous fungal insect pathogen that serves as a main source of wide-spectrum fungal insecticides. The deletion of smt3 led to significant growth defects on the minimal media with different carbon and nitrogen sources, an obvious reduction (45.7 %) in aerial conidiation during optimal cultivation, and increasing sensitivities to metal ions, oxidation, cell wall perturbation, and the fungicide carbendazim during conidial germination and/or colony growth. Compared with the wild-type, the percentage of germination of conidia stored at 4 °C decreased by 83.9 %, and virulence to Galleria mellonella via normal infection was delayed by 24.6 %. However, conidial thermotolerance increased slightly by 11.4 % in Δsmt3. These findings concurred with the repressed transcripts of some phenotype-related genes and decreased activities of antioxidant enzymes. Taken together, smt3 or sumoylation plays vital roles in the asexual development, environmental adaptation, and pathogenicity of B. bassiana.

中文翻译：

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Smt3 是酵母 SUMO 的同源物，有助于丝状昆虫病原体的无性发育、环境适应和宿主感染

小的泛素样修饰剂 (SUMO) 作为调节剂在 sumoylation 期间调节几个重要的真核细胞事件，但对 SUMO 或 sumoylation 在丝状昆虫病原体中的功能知之甚少。在这里，我们报告了单个 SUMO 编码基因 smt3 在白僵菌中的重要作用，白僵菌是一种丝状真菌昆虫病原体，是广谱真菌杀虫剂的主要来源。smt3 的缺失导致在不同碳源和氮源的基本培养基上出现显着的生长缺陷，在最佳培养过程中空气分生孢子明显减少（45.7 %），并增加对金属离子、氧化、细胞壁扰动和杀菌剂的敏感性孢子萌发和/或菌落生长期间的多菌灵。与野生型相比，4℃保存的分生孢子萌发率下降83.9%，正常感染对大蜡螟的毒力延迟24.6%。然而，分生孢子耐热性在 Δsmt3 中略微增加了 11.4%。这些发现与一些表型相关基因的转录抑制和抗氧化酶活性降低一致。总之，smt3 或 sumoylation 在 B. bassiana 的无性发育、环境适应和致病性中起着至关重要的作用。