Multigene Phylogeny Reveals Endophytic Xylariales Novelties from Dendrobium Species from Southwestern China and Northern Thailand.

Xiaoya Ma,Dinushani Anupama Daranagama,Mingkwan Doilom,Putarak Chomnunti,Jichuan Kang

doi:10.3390/jof8030248

Abstract

Xylariales are common endophytes of Dendrobium. However, xylarialean species resolution remains difficult without sequence data and poor sporulation on artificial media and asexual descriptions for only several species and old type material. The surface-sterilized and morph-molecular methods were used for fungal isolation and identification. A total of forty-seven strains were identified as twenty-three species belonging to Apiosporaceae, Hypoxylaceae, Induratiaceae, and Xylariaceae. Five new species—Annulohypoxylon moniliformis, Apiospora dendrobii, Hypoxylon endophyticum, H. officinalis and Nemania dendrobii were discovered. Three tentative new species were speculated in Xylaria. Thirteen known fungal species from Hypoxylon, Nemania, Nigrospora, and Xylaria were also identified. Another two strains were only identified at the genus and family level (Induratia sp., Hypoxylaceae sp.). This study recorded 12 new hosts for xylarialean endophytes. This is the first report of Xylariales species as endophytes from Dendrobium aurantiacum var. denneanum, D. cariniferum, D. harveyanum, D. hercoglossum, D. moniliforme, and D. moschatum. Dendrobium is associated with abundant xylarialean taxa, especially species of Hypoxylon and Xylaria. We recommend the use of oat agar with low concentrations to induce sporulation of Xylaria strains.

Highlights

Dendrobium Sw. is one of the three largest genera in Orchidaceae [1]
It is worth noting that five novel taxa with one cryptic species (Hypoxylaceae sp.) were introduced from forty-seven strains, which implied that fungal endophyte perhaps contains many unrecognized or cryptic species
Our results showed that the penzigioid species Xylaria berteri was repeatedly isolated from various Dendrobium organs in northern Thailand, while most Hypoxylaceae strains were from Chinese Dendrobium

Summary

Introduction

Dendrobium Sw. is one of the three largest genera in Orchidaceae [1]. Many Dendrobium orchids have important medicinal and ornamental values [2,3]. The majority of Dendrobium species are endangered due to low germination rates, habitat destruction, and over-exploitation as reported in the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Fungal endophytes play an important role in orchid development and defense against stress [4–7]. The symbiotic germination of eleven orchid species can be enhanced by some fungal endophytes [8,9]. Extracts of both Dendrobium and fungal endophytes have been found to possess various bioactivities such as angiogenesis inhibitory, anti-cancer, anti-inflammatory, anti-mutagenic, and anti-oxidative bioactive properties [10–16]

Methods

Results

Conclusion