The Diversity of Root-Associated Endophytic Fungi from Four Epiphytic Orchids in China

Tao Wang,Yu Yang,Yu Zhang,Donghuan Liu,Miao Chi,Ling Guo

doi:10.3390/d13050197

Abstract

Root-associated endophytic fungi (RAF) are found asymptomatically in almost all plant groups. However, little is known about the compositions and potential functions of RAF communities associated with most Orchidaceae species. In this study, the diversity of RAF was examined in four wild epiphytic orchids, Acampe rigida, Doritis pulcherrima, Renanthera coccinea, and Robiquetia succisa, that occur in southern China. A culture-independent method involving Illumina amplicon sequencing, and an in vitro culture method, were used to identify culturable fungi. The RAF community diversity differed among the orchid roots, and some fungal taxa were clearly concentrated in a certain orchid species, with more OTUs being detected. By investigating mycorrhizal associations, the results showed that 28 (about 0.8%) of the 3527 operational taxonomic units (OTUs) could be assigned as OMF, while the OTUs of non-mycorrhizal fungal were about 99.2%. Among the OMFs, Ceratobasidiaceae OTUs were the most abundant with different richness, followed by Thelephoraceae. In addition, five Ceratobasidium sp. strains were isolated from D. pulcherrima, R. succisa, and R. coccinea roots with high separation rates. These culturable Ceratobasidium strains will provide materials for host orchid conservation and for studying the mechanisms underlying mycorrhizal symbiosis.

Highlights

Endophytic fungi in living plants are found at certain stages of the life cycle without causing obvious disease symptoms [1]
The diversity of Root-associated endophytic fungi (RAF) in four wild tropical epiphytic orchid species located in southern China were examined by Illumina amplicon sequencing and culturing methods
The results showed that the colonization diversity, species richness, and community composition of the RAF varied among the four orchid species

Summary

Introduction

Endophytic fungi in living plants are found at certain stages of the life cycle without causing obvious disease symptoms [1]. Endophytic fungi are ubiquitous in the roots of Orchidaceae plants and are involved in the whole life cycle from seed germination to plant growth and development [3,4]. Most Orchidaceae mycorrhizal fungi (OMF) colonize the root cortex cells of orchids in the form of a knot or spiral hyphae. These hyphae offer nutrition for the orchids and promote plant growth, and can form symbioses with the orchids [5]. Researchers have extended OMF to include other fungal families such as Thelephoraceae, Russulaceae, Sebacinaceae, Cortinariaceae, and Clavulinaceae [7,8,9]

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Discussion

Conclusion