Plett Jonathan M, Sabotič Jerica, Vogt Eva, Snijders Fridtjof, Kohler Annegret, Nielsen Uffe N, Künzler Markus, Martin Francis, Veneault-Fourrey Claire
Université de Lorraine, INRAE, UMR 1136 Interactions Arbres-Microorganismes, Centre INRAE Grand Est-Nancy, Champenoux, France.
Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia.
Environ Microbiol. 2022 Oct;24(10):4607-4622. doi: 10.1111/1462-2920.16115. Epub 2022 Jul 11.
Fungivory of mycorrhizal hyphae has a significant impact on fungal fitness and, by extension, on nutrient transfer between fungi and host plants in natural ecosystems. Mycorrhizal fungi have therefore evolved an arsenal of chemical compounds that are hypothesized to protect the hyphal tissues from being eaten, such as the protease inhibitors mycocypins. The genome of the ectomycorrhizal fungus Laccaria bicolor has an unusually high number of mycocypin-encoding genes. We have characterized the evolution of this class of proteins, identified those induced by symbiosis with a host plant and characterized the biochemical properties of two upregulated L. bicolor mycocypins. More than half of L. bicolor mycocypin-encoding genes are differentially expressed during symbiosis or fruiting body formation. We show that two L. bicolor mycocypins that are strongly induced during symbiosis are cysteine protease inhibitors and exhibit similar but distinct localization in fungal tissues at different developmental stages and during interaction with a host plant. Moreover, we show that these L. bicolor mycocypins have toxic and feeding deterrent effect on nematodes and collembolans, respectively. Therefore, L. bicolor mycocypins may be part of a mechanism by which this species deters grazing by different members of the soil food web.
菌根菌丝的真菌摄食对真菌适应性有显著影响，进而对自然生态系统中真菌与宿主植物之间的养分转移产生影响。因此，菌根真菌进化出了一系列化学化合物，据推测这些化合物可保护菌丝组织不被食用，比如蛋白酶抑制剂真菌环肽。外生菌根真菌双色蜡蘑的基因组中编码真菌环肽的基因数量异常多。我们已经对这类蛋白质的进化进行了表征，鉴定出那些在与宿主植物共生时被诱导的蛋白质，并对两种上调表达的双色蜡蘑真菌环肽的生化特性进行了表征。超过半数的双色蜡蘑编码真菌环肽的基因在共生或子实体形成过程中差异表达。我们发现，两种在共生过程中强烈诱导表达的双色蜡蘑真菌环肽是半胱氨酸蛋白酶抑制剂，并且在真菌组织的不同发育阶段以及与宿主植物相互作用期间表现出相似但不同的定位。此外，我们表明这些双色蜡蘑真菌环肽分别对线虫和弹尾虫具有毒性和摄食威慑作用。因此，双色蜡蘑真菌环肽可能是该物种阻止土壤食物网中不同成员啃食的一种机制的一部分。
