PacC is a pH-responsive transcription factor gene highly expressed at alkaline pH and plays distinct roles in environmental fitness, conidiation and virulence of different fungi. Here, we show biological functions of orthologous MaPacC in the locust-specific fungal pathogen Metarhizium acridum. Disruption of MapacC slowed down the fungal growth only under alkaline conditions. Intriguingly, the fungal thermotolerance was enhanced by the MapacC deletion, accompanied by transcriptional upregulation of some heat shock-responsive genes. The disruptant suffered a reduction in conidial yield and a change in conidial surface structure, but showed little change in cell wall integrity. The virulence of the disruptant against a locust species was markedly attenuated due to delayed appressorium formation, repressed expression of some insect cuticle hydrolases and slowed growth in locust hemolymph. The phenoloxidase activity and nodules of the locusts infected by the disruptant were also boosted. All of these phenotypic changes were restored by targeted gene complementation. Our results indicate that MaPacC acts a negative regulator of thermotolerance and contributes to the virulence of M. acridum by an involvement in hyphal penetration through insect cuticle and evasion from insect immunity.

中文翻译：

---

MaPacC是一种pH响应性转录因子，可负调节热耐受性，并有助于cri变种的分生和毒力。

PacC是在碱性pH值下高表达的pH响应转录因子基因，在环境适应性，不同真菌的分生和毒力中起着独特的作用。在这里，我们显示了蝗虫特有的真菌病原体Meta桐中的直系同源MaPacC的生物学功能。仅在碱性条件下，MapacC的破坏才减慢了真菌的生长。有趣的是，通过MapacC缺失增强了真菌的耐热性，同时伴随着一些热激反应基因的转录上调。破坏剂的分生孢子产率降低，分生孢子表面结构发生变化，但细胞壁完整性几乎没有变化。由于app虫的延迟形成，破坏剂对蝗虫的毒性显着减弱，抑制了一些昆虫表皮水解酶的表达并减慢了蝗虫血淋巴的生长。破坏者感染的蝗虫的酚氧化酶活性和结节也得到增强。所有这些表型变化都通过靶向基因互补得以恢复。我们的结果表明，MaPacC充当负耐热性调节剂，并通过参与通过昆虫表皮的菌丝渗透和逃避昆虫免疫力而促进了a霉的毒性。