Decomposition potentialities of Epichloë bromicola from Elymus racemifer

Abstract

Fungal endophytes of the genus Epichloë possess weak saprotrophic abilities, but no quantitative studies have been conducted regarding their abilities to decompose grass litter. In the present study, Epichloë bromicola strains were isolated from Elymus racemifer, a common perennial grass in Japan, and assessed for their ability to decompose sterilised grass leaves under pure culture conditions. These abilities were compared with those of two non-systemic endophytic fungi, Phomopsis sp. and Biscogniauxia maritima, sympatrically encountered in the live tissues. Mass loss of leaves caused by 16 strains of E. bromicola on potato dextrose agar at 20 ^oC for 12 weeks ranged from 0.4% to 10.8% of the original leaf mass, with a mean of 4.9%. This value was not significantly different from that of Phomopsis sp. (mean mass loss of 5.6%) but was significantly lower than that of B. maritima (mean mass loss of 20.8%) measured under the same culture conditions. The low decomposing ability of E. bromicola suggests that this fungus is not responsible for significant decomposition of grass litter, which is consistent with the current belief that Epichloë endophytes obtain photosynthetic product from live plant tissues but rarely elongate hyphae on dead tissues.