外生菌根共生:共生真菌多样性及菌根形成的分子机制

Ectomycorrhizal symbioses:Diversity of mycobionts and molecular mechanisms that entail the development of ectomycorrhizae

大约2%的维管植物能够与17～18个目约280个属的真菌形成外生菌根关系.外生菌根关系的形成、宿主植物的专一化和宿主转移等事件可能是共生真菌物种分化的重要驱动力.比较基因组学研究发现,外生菌根真菌丢失了大量与植物细胞壁物质降解相关的基因.在外生菌根形成过程中,真菌与宿主植物之间借助多样化的信号分子完成相互识别,并且外生菌根真菌能够借助分泌效应蛋白抑制宿主植物的防御反应,促进菌根形成.本文对外生菌根真菌的多样性和分布规律,以及外生菌根形成的分子机制等方面进行了综述,并据此对后续研究提出展望.

Approximately 2%of vascular plants are involved in ectomycorrhizal symbioses with about 280 genera of higher fungi from 17–18 fungal orders.The development of ectomycorrhizal symbiosis,host specificity,and host-switch events appear to be key drivers for the speciation of ectomycorrhizal fungi.Comparative genomics indicates that ectomycorrhizal fungi have lost a set of genes that control the decay of organic matter contained in plant cell walls.During the formation of ectomycorrhizae,mycobionts and host plants require diversified signaling molecules to induce their bilateral communication;at the same time,mycobionts can release some mycorrhizal-induced small secreted proteins,which can help them escape plant defenses and thereby enable them to colonize plant roots.We present a review on the diversity and geographical distribution pattern of ectomycorrhizal fungi and on molecular mechanisms contributing to the development of ectomycorrhizae.Based on this,we also suggeste several future prospects.