METABOLITES OF OPHIOSPHAERELLA-HERPOTRICHA, A CAUSE OF SPRING DEAD SPOT OF BERMUDAGRASS

Ophiosphaerella herpotricha, a cause of spring dead spot (SDS) of bermudagrass, produced seven metabolites in liquid culture. These were isolated and structurally identified as epoxydon, desoxyepoxydon, phyllostine, m-hydroxybenzyl alcohol, a cyclic peptide, destruxin-B, and two novel metabolites, 2,4-dihydroxy-6-(2-hydroxyethyl)-3-methoxyacetophenone and 6-acetoxy-4,5-dihydroxy-2-hydroxymethylcyclohex-2-enone. All metabolites, except destruxin-B, caused necrosis when spotted onto leaves of bermudagrass and other plant species. Destruxin-B, previously reported as a host-specific toxin on Brassica napus, failed to cause necrosis on leaves of bermudagrass cultivars susceptible to SDS. Bermudagrass cultivars varied in their sensitivity to epoxydon, the major metabolite isolated. However, there was no correlation between the amount of leaf necrosis caused by epoxydon and resistance of the cultivars to SDS in the field.