Data from: A lectin-mediated resistance of higher fungi against predators and parasites

Fruiting body lectins are ubiquitous in higher fungi and characterized by being synthesized in the cytoplasm and up-regulated during sexual development. The function of these lectins is unclear. A lack of phenotype in sexual development upon inactivation of the respective genes argues against a function in this process. We tested a series of characterized fruiting body lectins from different fungi for toxicity towards the nematode Caenorhabditis elegans, the mosquito Aedes aegypti and the amoeba Acanthamoeba castellanii. Most of the fungal lectins were found to be toxic towards at least one of the three target organisms. By altering either the fungal lectin or the glycans of the target organisms, or by including soluble carbohydrate ligands as competitors, we demonstrate that the observed toxicity is dependent on the interaction between the fungal lectins and specific glycans in the target organisms. The toxicity was found to be dose-dependent such that low levels of lectin were no longer toxic but still led to food avoidance by C. elegans. Finally, we show, in an ecologically more relevant scenario, that challenging the vegetative mycelium of Coprinopsis cinerea with the fungal-feeding nematode Aphelenchus avenae induces the expression of the nematotoxic fruiting body lectins CGL1 and CGL2. Based on these findings, we propose that filamentous fungi possess an inducible resistance against predators and parasites mediated by lectins that are specific for glycans of these antagonists.

子实体凝集素（fruiting body lectins）广泛分布于高等真菌中，其典型特征为在细胞质内合成，并在有性发育阶段表达上调。目前此类凝集素的功能仍不明确。将对应基因失活后未观察到有性发育出现异常表型，这提示其可能并不参与该发育过程。我们针对一系列已完成表征的不同真菌来源的子实体凝集素，检测其对三类靶标生物的毒性：线虫秀丽隐杆线虫（Caenorhabditis elegans）、蚊子埃及伊蚊（Aedes aegypti）以及变形虫卡氏棘阿米巴（Acanthamoeba castellanii）。结果显示，多数受试真菌凝集素可对至少一种靶标生物产生毒性。通过对真菌凝集素或靶标生物的糖基化聚糖进行改造，或添加可溶性碳水化合物配体作为竞争性抑制剂，我们证实该毒性效应依赖于真菌凝集素与靶标生物表面特定糖基化聚糖之间的特异性相互作用。进一步研究发现该毒性呈现剂量依赖性：当凝集素浓度较低时，虽不再具备毒性，但仍可诱导秀丽隐杆线虫产生食物规避行为。最后，我们在更贴合自然生态的实验场景中证实：以取食真菌的燕麦真滑刃线虫（Aphelenchus avenae）侵染灰盖鬼伞（Coprinopsis cinerea）的营养菌丝体，可诱导线虫毒性子实体凝集素CGL1与CGL2的表达。基于上述研究结果，我们提出假说：丝状真菌可通过靶向捕食者与寄生生物糖基化聚糖的凝集素，获得诱导型抗捕食及抗寄生抗性。