Biotechnology Research Center, Southwest University, Beibei, Chongqing, People's Republic of China.
College of Biological and Chemical Engineering, Chongqing University of Education, Chongqing, People's Republic of China.
Microbiol Spectr. 2022 Feb 23;10(1):e0206621. doi: 10.1128/spectrum.02066-21. Epub 2022 Feb 9.
The entomopathogenic fungus Beauveria bassiana is a typical filamentous fungus and has been used for pest biocontrol. Conidia are the main active agents of fungal pesticides; however, we know little about conidial developmental mechanisms and less about maturation mechanisms. We found that a ZnCys transcription factor of bassiana (named BbCmr1) was mainly expressed in late-stage conidia and was involved in conidium maturation regulation. Deletion of impaired the conidial cell wall and resulted in a lower conidial germination rate under UV (UV), heat shock, HO, Congo red (CR) and SDS stresses compared to the wild type. Transcription levels of the genes associated with conidial wall components and trehalose synthase were significantly reduced in the mutant. Further analysis found that BbCmr1 functions by upregulating BbWetA, a well-known transcription factor in the central development of BrlA-AbaA-WetA. The expression of was positively regulated by BbBrlA. These results indicated that BbCmr1 played important roles in conidium maturation by interacting with the central development pathway, which provided insight into the conidial development networks in bassiana. Conidium maturation is a pivotal event in conidial development and affects fungal survival ability under various biotic/abiotic stresses. Although many transcription factors have been reported to regulate conidial development, we know little about the molecular mechanism of conidium maturation. Here, we demonstrated that the transcription factor BbCmr1 of bassiana was involved in conidium maturation, regulating cell wall structure, the expression of cell wall-related proteins, and trehalose synthesis. BbCmr1 orchestrated conidium maturation by interplaying with the central development pathway BrlA-AbaA-WetA. BbBrlA positively regulated the expression of , and the latter positively regulated expression, which forms a regulatory network mediating conidial development. This finding was critical to understand the molecular regulatory networks of conidial development in bassiana and provided avenues to engineer insect fungal pathogens with high-quality conidia.
球孢白僵菌是一种典型的丝状真菌，已被用于害虫的生物防治。分生孢子是真菌农药的主要活性成分；然而，我们对分生孢子发育机制知之甚少，对成熟机制知之更少。我们发现，球孢白僵菌的一个 ZnCys 转录因子（命名为 BbCmr1）主要在晚期分生孢子中表达，并参与调节分生孢子成熟。与野生型相比，缺失 导致分生孢子细胞壁受损，在 UV（紫外线）、热休克、HO、刚果红（CR）和 SDS 胁迫下，分生孢子萌发率降低。 突变体中与分生孢子壁成分和海藻糖合酶相关的基因转录水平显著降低。进一步分析发现，BbCmr1 通过上调 BrlA-AbaA-WetA 中心发育过程中的一个众所周知的转录因子 BbWetA 发挥作用。 的表达受 BbBrlA 的正向调控。这些结果表明，BbCmr1 通过与中央发育途径相互作用在分生孢子成熟中发挥重要作用，这为球孢白僵菌分生孢子发育网络提供了新的见解。分生孢子成熟是分生孢子发育的关键事件，影响真菌在各种生物/非生物胁迫下的生存能力。尽管已经报道了许多转录因子来调节分生孢子发育，但我们对分生孢子成熟的分子机制知之甚少。在这里，我们证明了 bassiana 的转录因子 BbCmr1 参与了分生孢子成熟，调节细胞壁结构、细胞壁相关蛋白的表达和海藻糖合成。BbCmr1 通过与中央发育途径 BrlA-AbaA-WetA 相互作用来协调分生孢子成熟。BbBrlA 正向调控 的表达，后者正向调控 的表达，形成一个调节分生孢子发育的调控网络。这一发现对于理解球孢白僵菌分生孢子发育的分子调控网络至关重要，并为工程具有高质量分生孢子的昆虫真菌病原体提供了途径。
