Seasonal diversity and spaciotemporal distribution of fungal endophytes associated with the medicinal plant Coleus forskohlii Briq.

Fungi that colonize the healthy tissues of the plants without showing any disease symptoms in the host plants are termed as fungal endophytes. The presence of fungal endophytes provides a positive effect on the host's growth and development and also triggers the production of some essential bioactive compounds in the host. This study was undertaken to isolate, identify and understand the spaciotemporal distribution and seasonal diversity of fungal endophytes associated with the leaf, stem and root of Coleus forskohlii, an important and endangered medicinal plant. Sampling was done for a period of 12 months between May 2020-April 2021. A total of 950 fungal endophytes were isolated from a total of 1680 tissues of the leaf, stem and root of C. forskohlii. The fungi were identified based on their morphological features and some of them were identified by molecular identification by 18S rRNA sequencing. The endophytic isolates belonged to 10 different orders belonging to 3 different classes-Sordariomycetes (Hypocreales, Xylariales, Microascales, Trichosphaeriales, Glomerellales and Sordariales), Dothiomycetes (Pleosporales, Capnodiales, Botryosphaeriales) and Eurotiomyctes (Eurotiales). About 81.26% of the isolates belonged to Ascomycota and 2.63% of the isolates belonged to Mucoromycota. Chaetomium globosum, Collariella bostrychodes, C. robusta, Colletotrichum gloeosporioides, Fusarium chlamydosporum, Sterile hyaline mycelia, Aspergillus niger, Xylaria curta, X. grammica, Mucor circinelloides and Trichoderma harizianum were the frequently isolated species of fungi. C. globosum, C. bostrychodes, C. gloeosporioides, sterile hyaline mycelia and X. curta were found distributed in all the tissues of the plant. C. forskohlii has thus revealed a rich diversity of fungal endophytes that could be isolated and cultured to yield some pharmacologically important bioactive compounds.