Institute of Microbiology, University of Innsbruck, Innsbruck, Austria.
Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria.
Sci Rep. 2018 Aug 13;8(1):12064. doi: 10.1038/s41598-018-30500-y.
Mycoparasites, e.g. fungi feeding on other fungi, are prominent within the genus Trichoderma and represent a promising alternative to chemical fungicides for plant disease control. We previously showed that the seven-transmembrane receptor Gpr1 regulates mycelial growth and asexual development and governs mycoparasitism-related processes in Trichoderma atroviride. We now describe the identification of genes being targeted by Gpr1 under mycoparasitic conditions. The identified gene set includes a candidate, sfp2, encoding a protein of the fungal-specific Sur7 superfamily, whose upregulation in T. atroviride upon interaction with a fungal prey is dependent on Gpr1. Sur7 family proteins are typical residents of membrane microdomains such as the membrane compartment of Can1 (MCC)/eisosome in yeast. We found that GFP-labeled Gpr1 and Sfp2 proteins show partly overlapping localization patterns in T. atroviride hyphae, which may point to shared functions and potential interaction during signal perception and endocytosis. Deletion of sfp2 caused heavily altered colony morphology, defects in polarized growth, cell wall integrity and endocytosis, and significantly reduced mycoparasitic activity, whereas sfp2 overexpression enhanced full overgrowth and killing of the prey. Transcriptional activation of a chitinase specific for hyphal growth and network formation and strong downregulation of chitin synthase-encoding genes were observed in Δsfp2. Taken together, these findings imply crucial functions of Sfp2 in hyphal morphogenesis of T. atroviride and its interaction with prey fungi.
菌寄生现象，例如以其他真菌为食的真菌，在木霉属中很常见，是一种有前途的替代化学杀菌剂来控制植物病害的方法。我们之前曾表明，七跨膜受体 Gpr1 调节菌丝生长和无性发育，并控制木霉属中与菌寄生相关的过程。我们现在描述了在菌寄生条件下 Gpr1 靶向的基因的鉴定。所鉴定的基因集包括一个候选基因 sfp2，它编码真菌特异性 Sur7 超家族的蛋白质，其在与真菌猎物相互作用时在 T. atroviride 中的上调依赖于 Gpr1。Sur7 家族蛋白是酵母中典型的膜微区（如 Can1（MCC）/eisosome 的膜隔室）的常驻蛋白。我们发现，GFP 标记的 Gpr1 和 Sfp2 蛋白在 T. atroviride 菌丝中表现出部分重叠的定位模式，这可能表明在信号感知和内吞作用过程中有共同的功能和潜在的相互作用。sfp2 的缺失导致菌落形态严重改变、极化生长、细胞壁完整性和内吞作用缺陷，以及菌寄生活性显著降低，而 sfp2 的过表达增强了对猎物的完全过度生长和杀伤。观察到针对菌丝生长和网络形成的特定几丁质酶的转录激活，以及几丁质合酶编码基因的强烈下调。总之，这些发现表明 Sfp2 在 T. atroviride 菌丝形态发生及其与猎物真菌相互作用中具有重要功能。
