Study of Biodiversity And Bioactivity Of Entophytic Fungi of Some Himalayan Conifers of Nepal

Abstract

A study was conducted with the aim of studying the biodiversity and bioactivity ofendophytic fungi from selected Himalayan conifers collected from different locationviz. Taxus wallichiana (‘Kavre’, 2,930m), Abies spectabilis (‘Kavre’, 2,930m),Podocarpus nerifolius(‘Kirtipur’, 1,372m) andJuniperus indica(‘Kirtipur’, 1,372m) Altogether 47 endophytes were isolated from the inner bark of the above mentionedHimalayan conifers. Only 29 fungal isolates could be identified. The mostrepresentative fungal isolates identified up to the genus level belonged to the generaPestalotiopsis, Alternaria, Trichoderma, Aspergillus, Paecilomyces, Nigrospora,Helicomyces, Drechslera, Helminthosporium and an endomycorrhiza identified asGlomusspp. The identified endophytic fungal isolates were subjected for screening purpose for theirantifungal activities against the plant pathogenic fungi viz. Fusarium oxysporum,Fusarium moniliforme, Sclerotinia spp., Helminthosporium spp., Alternaria spp.,Geotrichum spp., andGloesporium sporioides by following the dual culture method.The observation revealed that most of the endophytic fungi showed antifungal activitiesagainst plant pathogenic fungi used in this study but Pestalotiopsis spp., Alternariaspp., Trichoderma spp. andHelminthosporium spp. were the ones among showinghighest bioactivity against all the fungal plant pathogens used in the study. Thebioactivity was due to the production of novel bioactive secondary metabolites by theseendophytic fungi. The different isolates of Pestalotiopsisspp., NT-801a, NP-601 and NJ-702 each fromdifferent plant source were chosen as the priority isolates, for fermentation andextraction of novel bioactive secondary metabolites. The dry weight of fungal extractrecorded was 33 mg/500 ml for NT-801a isolate, 17mg/500 ml for NP-601 isolate and32 mg/500 ml for NJ-702 isolate. The presence of the bioactive secondary metabolite in the fungal extract was confirmedby the inhibitory activity against the test fungal plant pathogens. Among the fungalextract, thePestalotiopsis spp. (NJ-702) isolated fromJuniperus indica, showed themaximum inhibitory effect against most of the test fungal plant pathogens, compared tothe other two fungal extracts ofPestalotiopsisspp. isolated from different plant sources. The crude extract was further subjected to TLC analysis. The crude extract was made torun along with authentic taxol and its precursor compound(10-DAB III), as thereference compounds. The R value of the authentic taxol being 0.77 and that of thefungal analyte (NT-801a) being 0.78, (NP-601) being 0.79 and that of (NJ-702) being0.78, suggests the possibility of presence of taxol in all the three fungal extracts.