Indole-3-Acetic Acid Production by Colletotrichum siamense, An Endophytic Fungus from Piper nigrum Leaves

Abstract

Plant endophytic fungi have been recognized as an important and a good source of natural bioactive products with potential application in agriculture, medicine and food industry. Chemical and biological studies of fungal metabolites originating from endophytic fungi isolated in Sri Lanka are relatively less studied. Therefore we investigated the chemistry and bioactivity of endophytic fungi present in leaves of Piper nigrum L. (black pepper) of the family Piperaceae famed as the spices king due to its pungent quality. A fungal endophyte isolated from the leaves of P. nigrum was identified as Colletotrichum siamense through molecular biological means using internal transcribed spacer (ITS) region of rDNA gene. This is the first report of the isolation of C. siamense from Piperaceae. The fungus was fermented in potato dextrose media and the fungal media were extracted with EtOAc. Chromatographic separation of the EtOAc extract over silica gel, Sephadex LH-20 and preparative thin layer chromatography furnished indole-3-acetic acid (IAA) and uracil. IAA showed high antifungal activity against the common plant pathogenic fungus Cladosporium cladosporiodies by TLC bioautography method and antioxidant activity against DPPH radical by spectrophotometry method.