Strobel,GA (reprint author),Montana State Univ,Dept Plant Sci,Bozeman,MT 59717 USA.
An endophyte (PC27-5) was isolated from stem tissue of Western hemlock (Tsuga heterophylla) in a Pacific Northwest temperate rainforest. Phylogenetic analyses, based on ITS-5.8S rDNA and 18S rDNA sequence data, combined with cultural and morphological analysis showed that endophyte PC27-5 exhibited all characteristics of a fungus identical to Coniochaeta velutina. Furthermore, wide spectrum antimycotics were produced by this endophyte that were active against such plant pathogens as Sclerotinia sclerotiorum, Pythium ultimum, and Verticillium dahliae and lethal to Phythophthora cinnamomi, Pythium ultimum, and Phytophthora palmivora in plate tests. The bioactive components were purified through organic solvent extraction, followed by silica column chromatography, and finally preparative HPLC. The minimum inhibitory concentration of the active fraction to Pythium ultimum, which was gained from preparative HPLC, was 11 mu g/ml. UPLC-HRMS analysis showed there were two similar components in the antimycotic fraction. Their molecular formulae were established as C30H22O11 (compound I) and C30H22O10 (compound II) respectively, and preliminary spectral results indicate that they are anthroquinone glycosides. Other non-biologically active compounds were identified in culture fluids of this fungus by spectral means as emodin and chrysophanol - anthroquinone derivatives. This is the first report that Coniochaeta velutina as an endophyte produces bioactive antifungal components.
1.Southwest Univ, Coll Biotechnol, State Key Lab Silkworm Genome Biol, Chongqing 400715, Peoples R China 2.Montana State Univ, Dept Plant Sci, Bozeman, MT 59717 USA 3.Chinese Acad Sci, Kunming Inst Bot, State Key Lab Phytochem & Plant Resources West Ch, Kunming 650201, Peoples R China 4.Brigham Young Univ, Dept Plant & Wildlife Sci, Provo, UT 84602 USA