外来植物紫茎泽兰入侵对菌根菌群落的影响

为了研究紫茎泽兰(Ageratina adenophora)入侵对土壤菌根真菌(mycorrhizal fungi, MF)群落的影响,采用嵌套PCR 技术分析了外来植物紫茎泽兰入侵生境内土著植物群落、土著植物与紫茎泽兰混生群落、紫茎泽兰单优群落中, 侵染紫茎泽兰及土著植物的MF 群落结构, 及紫茎泽兰与土著植物根围土壤中MF 群落结构。结果表明, 紫茎泽兰不同入侵进程MF 群落结构存在差异, 其中, 从土著植物群落的植物根内检测到内养球囊霉(Glomus intraradices)型克隆; 从土著植物与紫茎泽兰混生群落的紫茎泽兰根内也检测到内养球囊霉型克隆, 而在土著植物根内检测到1 个球囊霉属(Glomus sp 2)型克隆; 从紫茎泽兰单优群落的紫茎泽兰根内未检测到MF, 但从其根围土壤中检测到2 个球囊霉属(Glomus sp 1 和Glomus sp 2)型克隆。在土著植物与紫茎泽兰混生群落中, 从紫茎泽兰根围土壤中检测到4 个克隆型, 分别为毛舌菌阔孢(Trichoglossum hirsutum)、皂味口磨(Tricholoma saponaceum)、亚盖趋本菌(Xylobolus subpileatus)和翘鳞肉齿菌(Sarcodon imbricatus), 从土著植物根围土壤中也检测到4 个克隆型, 分别为小皮伞(Camarophyllopsis hymenocephala)、肉色香蘑(Lepista irina)、皂味口磨及亚侧耳(Panellus serotinus)型克隆; 在土著植物群落中, 从根围土壤只检测到皂味口磨型克隆。紫茎泽兰入侵改变了土著MF 群落结构, 其中在土著植物占据的土壤中以外生菌根真菌为主, 而外来植物紫茎泽兰则更多地积累了丛枝菌根真菌。文中讨论了紫茎泽兰改变入侵地土壤菌根菌群落及其可能对紫茎泽兰入侵的反馈。

Effects of exotic plant Ageratina adenophora invasion on mycorrhizal fungal community

The invasion of exotic plants and probability of successful invasion are affected by the interaction between exotic plants and soil microbes in invaded habitats. Furthermore, interactions among mycorrhizal fungi (MF) and exotic plants have been the focus of the response of soil microbial mechanisms to plant invasion. This study used nested PCR to detect MF in roots and rhizosphere soils of native weeds and A. adenophora in native weeds dominated community, A. adenophora and native weeds mixed community, and A. adenophora dominated community in A. adenophora invaded habitats. The results showed that MF community structures were different for different invasion phases. Glomus intraradices clones were detected in roots of native weeds grown in native weeds dominated community. G. intraradices clones were also noted in roots of A. adenophora grown in A. adenophora and native weeds mixed community. Only one Glomus (Glomus sp 2) clone was found in the roots of native weeds grown in A. adenophora and native weeds mixed community. No MF was detected in the roots of A. adenophora grown in A. adenophora dominated communities. Also two Glomus (Glomus sp 1 and Glomus sp 2) clones were obtained in the rhizosphere soils of A. adenophora dominated community. Trichoglossum hirsutum, Tricholoma saponaceum, Xylobolus subpileatus and Sarcodon imbricatus were detected in rhizosphere soils of A. adenophora grown in A. adenophora and native weeds mixed community. Camarophyllopsis hymenocephala, Lepista irina, T. saponaceum and Panellus serotinus were found in rhizosphere soils of native weeds grown in A. adenophora and native weeds mixed community. T. saponaceum was found in rhizosphere soils of native weeds grown in native weeds dominated communities. MF communities were changed by A. adenophora invasion and ectomycorrhizal fungi (EMF) more likely habited native weeds rhizosphere soils than A. adenophora rhizosphere soils. Arbuscular mycorrhizal fungi (AMF) accumulated more in rhizosphere soils of exotic A. adenophora than in native weeds rhizosphere soils. The probability of invasion changed MF community response to A. adenophora invasion, which suggested that A. adenophora heartened AMF in rhizosphere soils and induced positive AMF feedback, which enhanced A. adenophora invasiveness. The study highlighted one of the important soil microbial mechanisms of A. adenophora invasion in southeast China.