Discovering fungal communities in roots of Zoysia japonica and characterising novel species and their antifungal activities

Abstract

Turf-grasses are economically important horticultural crops, which have been utilised by humans to improve the environment for more than a thousand years. Turf-grasses are widely distributed in landscapes, slopes and sport fields, such as golf courses. Endophytic fungi are a resource of unexplored fungal diversity with potential bioactive compounds. In this study, culture-independent ITS amplicon sequencing and culture-dependent isolation methods were used to reveal fungal community in roots of the turf-grass Zoysia japonica. A total of 317 OTUs were identified from root samples of Z. japonica by analysis of ITS amplicon reads. Fungal community was dominated by Sordariales (32.45%), followed by Chaetothyriales (18.16%), unknown taxa in Sordariomycetes (14.63%) and Pleosporales (12.48%). During isolation, 151 endophytic fungal strains were obtained from roots of Z. japonica and a variety of taxa were found by ITS amplification and sequencing. Moreover, 11 endophytic fungal species were further characterised in this study, based on morphological characterisation and multi-loci phylogenetic analysis, including Niesslia dimorphospora, a newly-recorded species in Korea and 10 novel species (Dactylaria hwasunensis sp. nov., Lophiostoma jeollanense sp. nov., Magnaporthiopsis zoysiae sp. nov., Poaceascoma endophyticum sp. nov., P. koreanum sp. nov., P. magnum sp. nov., P. zoysiiradicicola sp. nov., Stagonospora endophytica sp. nov., Setophoma zoysiae sp. nov. and Pseudorhypophila poae sp. nov.). Antifungal activities of these species were tested against the turf-grass brown patch pathogen Rhizoctonia solani AG2-2(IIIB), with S. zoysiae being the best antagonist. In addition, butanol extract from mycelia of S. zoysiae strongly inhibited R. solani AG2-2(IIIB) in vitro and in planta. The results of this study expand the biodiversity of endophytic fungi and revealed potential biological resources for future turf-grass management and bioactive compound exploitation.