College of Agricultural and Food Science, Zhejiang A&F University, Lin'an 311300, Zhejiang, China.
MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China.
Cells. 2020 Mar 5;9(3):626. doi: 10.3390/cells9030626.
Non-rhythmic conidiation favors large-scale production of conidia serving as active ingredients of fungal insecticides, but its regulatory mechanism is unknown. Here, we report that two FREQUENCY (FRQ) proteins (Frq1/2) governed by a unique FRQ-interacting RNA helicase (FRH) orchestrate this valuable trait in , an asexual insect-pathogenic fungus. Frq1 (964 aa) and Frq2 (583 aa) exhibited opposite expression dynamics (rhythms) in nucleus and steadily high expression levels in cytoplasm under light or in darkness no matter whether one of them was present or absent. Such opposite nuclear dynamics presented a total FRQ (pooled Frq1/2) level sufficient to persistently activate central developmental pathway in daytime and nighttime and supports continuous (non-rhythmic) conidiation for rapid maximization of conidial production in a fashion independent of photoperiod change. Importantly, both nuclear dynamics and cytoplasmic stability of Frq1 and Frq2 were abolished in the absence of the FRH-coding gene nonessential for the fungal viability, highlighting an indispensability of FRH for the behaviors of Frq1 and Frq2 in both nucleus and cytoplasm. These findings uncover a novel circadian system more complicated than the well-known model that controls rhythmic conidiation, and provide a novel insight into molecular control of non-rhythmic conidiation in .
非节律性分生孢子形成有利于大规模生产作为真菌杀虫剂有效成分的分生孢子，但这种调控机制尚不清楚。在这里，我们报告了两个 FREQUENCY（FRQ）蛋白（Frq1/2）受一种独特的 FRQ 相互作用 RNA 解旋酶（FRH）的调控，在无性昆虫病原真菌中控制这一有价值的特征。Frq1（964 个氨基酸）和 Frq2（583 个氨基酸）在细胞核中表现出相反的表达动力学（节律），无论它们是否存在，在光照或黑暗下细胞质中始终保持高表达水平。这种相反的核动力学呈现出足够的总 FRQ（聚合的 Frq1/2）水平，足以持续激活中央发育途径，在白天和夜间支持连续（非节律性）分生孢子形成，以一种独立于光周期变化的方式快速最大化分生孢子的产生。重要的是，在 FRH 编码基因缺失的情况下，Frq1 和 Frq2 的核动力学和细胞质稳定性都被消除，而 FRH 对真菌生存非必需，这突出了 FRH 对 Frq1 和 Frq2 在细胞核和细胞质中的行为的不可或缺性。这些发现揭示了一种比控制节律性分生孢子形成的著名 模型更复杂的新型生物钟系统，并为 中的非节律性分生孢子形成的分子控制提供了新的见解。
