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

Abstract:

[Objective] Plant root-associated fungi (RAF) are essential to the ecological processes involving organic mass 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 Phialocephala fortinii, symbiotic fungi Pezoloma ericae, and ectomycorrhizal Meliniomyces sp. In addition, saprotrophs Myceana sp., Lachnum virgineum, Herpotrichia sp. were also common in the RAF community of the two Rhododendron. These finding suggests the 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.