School of Life Sciences, Anhui University, Hefei 230601, Anhui, China.
Key Laboratory of Human Microenvironment and Precision Medicine of Anhui Higher Education Institutes, Anhui University, Hefei 230601, Anhui, China.
FEMS Microbiol Lett. 2022 Feb 24;369(1). doi: 10.1093/femsle/fnac013.
Nematode-trapping fungi are natural enemies of nematodes in nature. Arthrobotrys oligospora, a typical nematode-trapping fungus with a clear genetic background, can capture and infect nematodes by forming adhesive three-dimensional networks. Lectins, a class of glycoproteins containing glycosyl-specific recognition domains, play an important role in biological recognition. However, the fucose-specific lectins have rarely been studied regarding the process of preying on nematodes. In this study, we characterized the biological role of the fucose-specific lectin-encoding gene AOL_s00054g276 (g276) in A. oligospora. The gene g276 was first deleted based on homologous recombination, then the phenotype and nematocidal activity of the Δg276 mutant was evaluated. The results showed that the deletion of gene g276 delayed trap formation and weakened its nematocidal activity; however, mycelial growth, conidia production, conidial germination rates and adaption to environmental stresses were not affected. Our results suggest that the fucose-specific lectin-encoding gene g276 might be associated with the morphogenesis of this fungus, and its deletion resulted in a significantly low density of three-dimensional traps (P < 0.05) and a significantly low nematode-trapping efficiency (P < 0.001). These findings provide a basis for further elucidating the mechanism of A. oligospora preying on nematodes and lay a foundation for the development and utilization of fungal-derived lectins for nematode control in the future.
线虫诱捕真菌是自然界中线虫的天敌。节丛孢菌（Arthrobotrys oligospora）是一种典型的具有明确遗传背景的线虫诱捕真菌，它可以通过形成粘性的三维网络来捕获和感染线虫。凝集素是一类含有糖基特异性识别结构域的糖蛋白，在生物识别中发挥着重要作用。然而，关于捕食线虫过程中的果糖特异性凝集素研究甚少。在这项研究中，我们对节丛孢菌中果糖特异性凝集素编码基因 AOL_s00054g276（g276）的生物学作用进行了表征。首先基于同源重组对基因 g276 进行缺失，然后评估了Δg276 突变体的表型和杀线虫活性。结果表明，基因 g276 的缺失延迟了陷阱的形成并削弱了其杀线虫活性；然而，菌丝生长、分生孢子产生、分生孢子萌发率和对环境胁迫的适应不受影响。我们的结果表明，果糖特异性凝集素编码基因 g276 可能与该真菌的形态发生有关，其缺失导致三维陷阱的密度显著降低（P < 0.05），线虫的捕获效率显著降低（P < 0.001）。这些发现为进一步阐明节丛孢菌捕食线虫的机制提供了依据，并为未来利用真菌来源的凝集素防治线虫奠定了基础。
