State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650091, PR China; Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming 650091, PR China.
State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650091, PR China; Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming 650091, PR China; School of Life Sciences, Yunnan University, Kunming 650091, PR China.
Fungal Genet Biol. 2018 Jul;116:42-50. doi: 10.1016/j.fgb.2018.04.011. Epub 2018 Apr 24.
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 HO, 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.
丝裂原活化蛋白（MAP）激酶 Slt2 是芽殖酵母细胞壁完整性途径中的关键参与者。在这项研究中，我们分别从捕食线虫真菌节丛孢（Arthrobotrys oligospora）和单端孢霉（Monacrosporium haptotylum）中功能表征了 Slt2 的同源物 AoSlt2 和 MhSlt2。我们发现，AoSlt2 和 MhSlt2 的缺失导致菌丝生长减少，对环境胁迫（如十二烷基硫酸钠、刚果红和 HO）的敏感性增加，并且无法产生分生孢子和捕食线虫结构。实时聚合酶链反应分析显示，与野生型菌株相比，突变体中与孢子形成相关的（AbaA、Sep2 和 MedA）和细胞壁合成相关的（Chs、Glu 和 Gfpa）基因的转录下调。此外，突变株表现出降低的细胞外蛋白水解活性和三个同源丝氨酸蛋白酶编码基因的转录减少。这些结果首次表明，MAP 激酶 Slt2 同源物在调节菌丝生长、分生孢子形成、捕食结构形成、抗逆性和不同的捕食线虫真菌物种节丛孢和单端孢霉的致病性方面发挥相似的作用。
