Biodiversity of microfungi on some forest plants

Abstract

Fungi are a hyper-diverse and heterogeneous group of microorganisms. They are an essential component of most ecosystems are as they are the major contributors to nutrient cycling, and the main organisms which can degrade lignocellulose in wood and leaves. In a fungal taxonomic context, accurate identification of fungal life-styles gives insight to the nutritional and ecological significance of a particular fungus. This study has documented and provided updated definitions for fungal life-styles including biotrophs, hemibiotrophs, necrotrophs, saprotrophs and endophytes. Fungal endophytes of symbionts in natural flora and inhabit living plant tissues. These mycobionts may ecologically benefit their host plants by increasing drought and disease resistance and enhancing growth. Isolation of endophytes were carried out based on cultural procedures through different in vitro techniques. Identification of endophytes were carried out based on morphology of fungi sporulating on artificial media and multi-gene phylogenies of DNA sequence data. The current study focused on taxonomic novelties and new host or geographical records of endophytic fungi associated with Magnolia liliifera collected from Yunnan Province, China and M. garrettii from Chiang Mai Province, Thailand. Magnolia species are economically important and used in furniture, ornamental plants in gardens, temple trees, flowers for decorations and valuable medicine in China. We obtained 56 endophytic isolates from Magnolia species, of which 54 belong to ascomycetes and two to basidiomycetes. The 56 isolates were identified in 31 taxa including eight new species and 23 new host and or geographical records. The results indicate that members of Sordariomycetes are dominant groups of endophytic fungi in M. liliifera and M. garretti. Considering the total endophytic isolates from M. lilifera and M. garretti, Sordariomycetes comprises the highest number of isolates with 82%, followed Dothideomycetes with 14% and Agaricomycetes with 4%. We also investigated and documented saprobic microfungi on dead twigs from different plant hosts from Annonaceae (Anomianthus dulcis, Cananga odorata, Desmos chinensis), Apocynaceae (Alstonia scholaris) and Magnoliaceae (M. champaca, M. garrettii, M. lilifera) in northern Thailand and Yunnan Province, China. We provide descriptions, illustrations and discussions on their familial placement based on phylogeny and morphological data. In this study we introduce a new genus Muriformispora in Neohendersoniaceae (Dothideomycetes). We also introduce 15 new species including,eight new species from Magnolia plants, four new species from A. dulcis, two new species from C. odorata and one new species from Al. scholaris. We provide an amended account of Hermatomyces to include the sexual morph. Additionally, we report 32 new host records from Magnolia sp., A. dulcis, C. odorata, D. chinensis and Al. scholaris. Plant-fungal interactions are highly diverse and complex. Fungi are able to acquire different survival strategies with different life-styles as saprotrophs, endophytes, and pathogens. In most instances, fungi maintain a continuum from biotrophy, through to necrotrophy and/or saprotrophy in nature. It is considered that endophytes can switch their nutritional mode (from saprotrophic to parasitic or vice versa) or/and life-styles (soil, fungi and decaying and living plants). We introduce Diaporthe chiangmaiensis sp. nov. which was recovered as a saprobe from dead twigs and an endophyte life-style from asymptomatic leaves of M. liliifera in Chiang Mai Province, Thailand. We report on the endophytic life-style of Lasiodiplodia pseudotheobromae from asymptomatic leaves and saprobic life-style from dead twigs from M. liliifera in Xishuangbanna, Yunnan Province, China. Further, we were able to identify Neopestalotiopsis saprophyta as endophytes from fresh leaves and as saprobes from dead leaves of M. lilifera in Yunnan, China. These findings suggest that the same species successfully occupy healthy plant tissues (leaves) as endophytes and later change their life-style to saprobes when plant tissues senescence.