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）在高等真菌中广泛分布，其特征为在细胞质中合成，并在真菌有性发育过程中表达上调。此类凝集素的生理功能迄今尚不明确：敲除其编码基因后，真菌有性发育未出现明显表型，这提示此类凝集素可能并不参与该发育过程。我们选取一系列已被表征的不同真菌来源的子实体凝集素，针对模式线虫秀丽隐杆线虫（Caenorhabditis elegans）、蚊虫埃及伊蚊（Aedes aegypti）以及棘阿米巴原虫（Acanthamoeba castellanii）开展毒性实验。结果显示，多数受试真菌凝集素至少对三种靶标生物中的一种具有毒性。通过调控真菌凝集素或靶标生物的糖基化修饰，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：观测到的毒性效应依赖于真菌凝集素与靶标生物表面特异性聚糖的相互作用。该毒性呈现剂量依赖性：当凝集素浓度较低时，虽不再具有杀伤性，但仍可引发秀丽隐杆线虫的食物规避行为。最后，我们在更贴近自然生态的实验体系中证实：以取食真菌的燕麦滑刃线虫（Aphelenchus avenae）侵染灰盖鬼伞（Coprinopsis cinerea）的营养菌丝体，可诱导该真菌表达具有线虫毒性的子实体凝集素CGL1与CGL2。基于上述实验结果，我们提出假说：丝状真菌可通过表达特异性识别天敌与寄生虫表面聚糖的凝集素，获得可诱导的抗捕食与抗寄生抗性。