Mitogen-activated protein (MAP) kinase Slt2 is a key player in the cell-wall integrity pathway of budding yeast. In this study, we functionally characterized Slt2 orthologs AoSlt2 and MhSlt2 from the nematode-trapping fungi Arthrobotrys oligospora and Monacrosporium haptotylum, respectively. We found that disruption of AoSlt2 and MhSlt2 led to reduced mycelial growth, increased sensitivity to environmental stresses such as sodium dodecyl sulfate, Congo red, and H2O2, and an inability to produce conidia and nematode-trapping structures. Real-time polymerase chain reaction-based analyses showed that the transcription of sporulation-related (AbaA, Sep2, and MedA) and cell wall synthesis-related (Chs, Glu, and Gfpa) genes was down-regulated in the mutants compared with the wild-type strains. Moreover, the mutant strains showed reduced extracellular proteolytic activity and decreased transcription of three homologous serine protease-encoding genes. These results show for the first time that MAP kinase Slt2 orthologs play similar roles in regulating mycelial growth, conidiation, trap formation, stress resistance, and pathogenicity in the divergent nematode-trapping fungal species A. oligospora and M. haptotylum.

中文翻译：

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MAP激酶Slt2直系同源物在两个捕获线虫的真菌的分生，陷阱形成和致病性中起着相似的作用。

丝裂原激活蛋白（MAP）激酶Slt2是发芽酵母细胞壁完整性途径中的关键角色。在这项研究中，我们在功能上分别从捕获线虫的真菌节肢动物寡孢单胞菌和单孢单胞菌八倍体中鉴定了Slt2直系同源基因AoSlt2和MhSlt2。我们发现破坏AoSlt2和MhSlt2会导致菌丝体生长减少，对环境压力（如十二烷基硫酸钠，刚果红和H2O2）的敏感性增加，并且无法产生分生孢子和线虫捕获结构。基于实时聚合酶链反应的分析表明，与突变体相比，突变体中与孢子形成相关的基因（AbaA，Sep2和MedA）和细胞壁合成相关的基因（Chs，Glu和Gfpa）的转录下调。野生型菌株。此外，突变株显示出降低的细胞外蛋白水解活性，并减少了三个同源丝氨酸蛋白酶编码基因的转录。这些结果首次表明，MAP激酶Slt2直系同源物在调节散布线虫捕获真菌物种A. oligospora和M. haptotylum的菌丝生长，分生，陷阱形成，逆境抗性和致病性方面起着相似的作用。