凉山州龙肘山锈红杜鹃与薄叶马银花根部真菌分子检测

Molecular diagnosis of root-associated fungi of Rhododendron bureavii and R. leptothrium in Longzhou mountain of Liangshan autonomous prefecture

【目的】为检验直接分子检测法用于揭示杜鹃花属(Rhododendron)植物根部真菌(Root-associated fungi,RAF)组成的有效性。【方法】采用不依赖于培养的分子检测技术直接从锈红杜鹃(R.bureavii)与薄叶马银花(R.leptothrium)的发根(Hair root)提取DNA,用真菌特异性引物扩增r DNA-ITS区、经克隆后测序,对获得的ITS序列进行分析;通过收集NCBI中与本研究的RAF相似性97%以上的所有序列对应的真菌来源(土壤或根系的身份)数据,分析真菌的生态学特性,并用FUNGuild软件提供的方法划分真菌的生态类型。【结果】从两种杜鹃花根部共检测到15种真菌,其中担子菌门(Basdiomycota)真菌3种,子囊菌门(Ascomycota)真菌12种。柔膜菌目(Helotiales)真菌在两种杜鹃花RAF群落中占据优势,并且在两种杜鹃花根系中均检测到该类真菌。此外,两种杜鹃花根部有多种生态类型的RAF共存,包括曾被频繁报道的杜鹃花类菌根菌Oidiodendron sp.和Rhizoscyphus sp.、内生真菌Phialocephala fortinii、共生一致病过渡型真菌Pezoloma ericae、外生菌根共生菌Meliniomyces sp.,以及腐生型真菌Myceana sp.、Lachnum virgineum、Herpotrichia sp.。【结论】直接分子检测法从两种杜鹃花属植物根部检测到的真菌谱系多样性较高、生态类型复杂,这一方法能较为全面地反映杜鹃花属植物RAF多样性。

[Objective] Plant root-associated fungi （RAF） are essential to the ecological processes involving organic matter decomposition, nutrients cycling of ecosystem, and density-dependent regulation of plant populations. Molecular and culture-dependent diagnosis is commonly used to study RAF community. To evaluate the effectiveness of culture-independent molecular technique on depicting the species composition of Rhododendron RAF communities. ]Methods] DNA was extracted from hair roots of R. bureavii and R. leptothrium, and then fungal ITS region was amplified using fungus-specific primers ITS1F and ITS4. ITS-PCR products were cloned, sequenced, and analyzed. Putative trophic mode and guild of RAF were assigned by linking sequences with metadata obtained from a systematic review of published works on RAF ecology from multiple independent studies, and by functional analysis provided by FUNGuild software. [Results] A total of 15 fungal species were identified from hair roots of both Rhododendron species. Of these fungi, 3 species are Basdiomycota and 12 species are Ascomycota. The dominant fungal group Helotiales sp. was detected in RAF community of both Rhododendron species. Fungal taxa on the two Rhododendron plant roots can be assigned to multiple trophic modes and guilds including known ericoid mycorrhizal symbionts Rhizoscyphus sp. and Oidiodendron sp., as well as repeatedly documented endophyte Phialoeephala fortinii, symbiotic fungi Pezoloma ericae, and ectomycorrhizal Meliniomyces sp. In addition, saprotrophs Myceana sp., Lachnum virgineum, Herpotriehia sp. were also common in the RAF community of the two Rhododendron. These finding suggests that phylogenetically distant and multiple trophic modes and guilds of fungi co-existing on the Rhododendron roots. [Conclusion] Culture independent molecular diagnosis used here is fast and reliable for fully revealing the Rhododendron plant RAF diversity.