Alternaria alternata and Neocosmospora sp. from the medicinal plant Euphorbia larica exhibit antagonistic activity against Fusarium sp., a plant pathogenic fungus

Abstract

In this study, endophytic fungi were isolated from Euphorbia larica Boiss. and their antagonistic potential against phytopathogenic fungi viz. Fusarium sp., Rosellinia sanctae-cruciana and Cladosporium sp. was evaluated using an in vitro confrontation assay. A total of four endophytic fungi were isolated from the roots of E. larica. Among them, two fungal isolates (SQUCC-F1-1 and SQUCC-F6-2) showed inhibitory activity against Fusarium sp. None of the fungal endophytes restricted the growth of Rosellinia sanctae-cruciana and Cladosporium sp. On the basis of multi-gene phylogenetic analysis, these two endophytic fungi were identified as Neocosmospora sp. (SQUCC-F1-1) and Alternaria alternata (SQUCC-F6-2). Scanning electron microscopic observation of hyphae of the phytopathogenic fungi from the dual culture plate revealed morphological abnormalities such as loss of turgidity, shrinkage and disintegration of the hyphae. Analysis of the metabolites produced by these endophytic fungi by GC-MS revealed the existence of various fatty acids, fatty acid methyl esters, hydrocarbons and alkanes, which have been previously demonstrated to have antimicrobial activity. The antagonistic activities of fungal endophytes from E. larica are reported for the first time.