The nematophagous fungus Purpureocillium lavendulum is a natural enemy of plant-parasitic nematodes, which cause severe economic losses in agriculture worldwide. The production of asexual spores (conidia) in P. lavendulum is crucial for its biocontrol activity against nematodes. In this study, we characterized the core regulatory genes involved in conidiation of P. lavendulum at the molecular level. The central regulatory pathway is composed of three genes, P. lavendulum brlA (PlbrlA), PlabaA, and PlwetA, which regulate the early, middle, and late stages of asexual development, respectively. The deletion of PlbrlA completely inhibited conidiation, with only conidiophore stalks produced. PlAbaA determines the differentiation of conidia from phialides. The deletion of PlwetA affected many phenotypes related to conidial maturation, including abscission of conidia from conidium strings, thickening of the cell wall layers, vacuole generation inside the cytoplasm, production of trehalose, tolerance to heat shock, etc. Comparative analyses showed that the upstream regulators of the core regulatory pathway of conidiation, especially the “fluffy” genes, were different from those in Aspergillus. Besides their roles in conidiation, the central regulators also influence the production of secondary metabolites, such as the leucinostatins, in P. lavendulum. Our study revealed a set of essential genes controlling conidiation in P. lavendulum and provided a framework for further molecular genetic studies on fungus-nematode interactions and for the biocontrol of plant-parasitic nematodes.

中文翻译：

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参与食线虫紫花紫草孢子形成的核心调控基因的功能表征

食线真菌Purpureocillium lavendulum是植物寄生线虫的天敌，在世界范围内造成严重的农业经济损失。P. lavendulum中无性孢子（分生孢子）的产生对于其对线虫的生物防治活性至关重要。在这项研究中，我们在分子水平上表征了参与P. lavendulum分生孢子的核心调控基因。中央调控通路由三个基因组成，P. lavendulum brlA ( PlbrlA )、PlabaA和PlwetA分别调控无性发育的早期、中期和晚期。PlbrlA的缺失完全抑制分生孢子，只产生分生孢子梗。PlAbaA 决定分生孢子与小球孢菌的区别。PlwetA的缺失影响了许多与分生孢子成熟相关的表型，包括分生孢子串的分生孢子脱落、细胞壁层增厚、细胞质内液泡的产生、海藻糖的产生、对热休克的耐受性等。 比较分析表明上游分生孢子核心调控途径的调控因子，尤其是“蓬松”基因，与曲霉属不同。除了它们在分生孢子中的作用外，中央调节剂还影响P. lavendulum中次生代谢物的产生，如亮氨酸抑制素. 我们的研究揭示了一组控制P. lavendulum分生孢子的基本基因，并为真菌-线虫相互作用的进一步分子遗传研究和植物寄生线虫的生物防治提供了框架。