Comparison of phylogenetic diversity and ecological types of root-associated fungi on Aquilaria sinensis and Dalbergia odorifera seedlings in an endangered plant restoration nursery of Hainan Island

Abstract:

[Background] Root-associated fungi (RAF) are essential for seedling survival, establishment and growth. However, little is known about the identity and ecological characteristics of RAFnaturally established on seedling roots. [Objective] To reveal phylogenetic diversities and ecological types of RAF naturally established on nursery grown seedling of Aquilaria sinensis and Dalbergia odorifera and to evaluate the host effects on RAF community structuring. [Methods] root samples were collected to extract DNA, from which fungal ITS region was amplified, cloned and sequenced by using both universal and specific fungal primer pairs. Phylogenetic placements of fungi were inferred by ITS sequence analysis. The putative trophic modes and guilds of RAF were assigned by functional analysis with the FUNGuild software. Effects of plant species, height, basal diameter and leaf area on root-associated fungal species composition were determined by non-metric multidimensional scaling (NMDS) analysis. [Results] A. sinensis and D. odorifera seedlings grown in nurseries were naturally colonized by a highly diverse suite of RAF, including Mucoromycota (51%), Ascomycota (43%) and Basidiomycota (6%). These RAF can be assigned to multiple trophic modes and guilds including symbiotroph (29 species) representing by Glomeromycetes sp. 2, Rhizophagus irregularis, and saprotroph (5 species) representing by Talaromyces pinophilus and Rhizopycnis vagum. In addition, two fungal species, Mycoleptodiscus sp. and Fusarium phaseoli were assigned to pathotroph, while ecological characteristics of 15 species are unclear. NMDS analysis indicated that the effects of host plant species, plant height, basal diameter and leaf area of seedling on root-associated fungi were not significant. However weak effect of plant height was found in Arbuscular mycorrhiza fungi fungal community. [Conclusion] The RAF inoculum is high in culture media of this nursery that seedlings were associated with phylogenetically distant and multiple trophic modes and guilds of fungi. Diversity of AMF might be underrepresented when universal primers such as ITS1F/ITS4 were applied to investigate the diversity of RAF community.