横断山脉亚高山带几种高山栎林下丛枝菌根菌(AMF)调查

Investigation of Arbuscular Mycorrhizal Fungi(AMF)in Several Alpine Oak Understory Forests in the Subalpine Zone of the Hengduan Mountains

[目的]明确横断山脉亚高山带高山栎林下AMF孢子分类地位。[方法]自横断山脉亚高山带不同地段选择6个高山栎根围土壤和根系样本,对其土壤中AMF孢子利用湿筛沉淀法进行选取。利用AMF特异引物对其ITS区段18S rRNA基因进行扩增,结合形态学与分子生物学手段对其进行鉴定,构建系统发育演化树并推测其亲缘关系。[结果]四川、西藏高山栎林下土壤AMF孢子与根系克隆为类球囊霉属(Paraglomus),云南香格里拉高山栎林下土壤AMF孢子与根系克隆为球囊霉属(Glomus)。克隆结果表明:AMF能够广泛存在于高山栎组植物根系。根系苯胺蓝染色结果可见明显类似丛枝和泡囊的结构。综合高山栎土壤AMF孢子与根际AMF鉴定结果认为,高山栎林下存在大量AMF,且目前不同采样地高山栎林下根围土和根系分别仅发现一种AMF存在,提示各高山栎同时仅能与一种AMF发生共生关系。此外,高山栎林下AMF孢子在演化过程中发生分化并介于Paraglomus与Glomus的分类地位之间,且西藏、四川地区AMF与云南香格里拉地区AMF存在差异。[结论]本研究发现,自然条件下横断山脉亚高山地区高山栎林下菌塘普遍存在AMF,且云南香格里拉地区高山栎根系AM与Glomus属更接近,说明AM在长期演化过程中随地域迁移出现分化。为了解横断山脉亚高山带高山栎林下AMF的形成与演化提供理论参考。

[Objective]To clarify the taxonomic status of AMF spores under the oak forest in the subalpine belt of the Hengduan Mountains.[Method]Six samples of alpine oak root enclosures and root systems were selected from different parts of the subalpine belt of the Hengduan Mountains,and AMF spores in the soil were selected by wet sieving sedimentation method.AMF-specific primers were used to amplify the 18S rRNA gene of the ITS region,which was identified by combining morphological and molecular biological means,and the phylogenetic relationships were constructed to infer their affinities.[Result]The results showed that AMF spores and root cloning consequences of alpine oak in Sichuan and Tibet were the genus Paraglomus.And the consequence of AMF cloning on the root surface and the AMF in soil of alpine oak in Shangri-La showed that AMF could exist in the inter-roots of alpine oak plants.These AMF were the genus Glomus.In addition,only one AMF was found in the root envelope and inter-root soil of alpine oak forest in different sampling sites,suggesting that AMF might have a symbiotic relationship with alpine oak.Aniline blue pigment staining result showed obvious arbuscular and vesicle structures in roots.In addition,the AMF spores under the Alpine oak forest differentiated during the evolution and were between the taxonomic status of Paraglomus and Glomus,and there were differences in AMF in Tibet,Sichuan and Shangri-La,Yunnan.[Conclusion]AMF generally exists in the pure understory root rhizosphere and interroot soil of alpine oak in the subalpine belt of the Hengduan Mountains,which provides a theoretical reference for understanding the formation and evolution of AMF in the understory of alpine oak in the subalpine belt of the Hengduan Mountains.