Collection of non-toxic endophyte strains adapted to cold and wet climate in northern Japan and development of new technology for its practical use

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The aim of this research project was to find non-toxic endophyte strains adapted to cold and wet climate in northern Japan and to study for the practical use. For this purpose, we systematically collected perennial ryegrass and tall fescue plants infected with Neotyphodium endophytes. Among them a perennial ryegrass plant collected from Fukaura, Aomori prefecture was low in ergovaline and lolitrem B contents which were toxic to livestock. Endophyte fungi of Fukaura perennial ryegrass ecotype were morphologically similar to wild type endophyte and identified as Neotyphodium lolii from the investigation of ribosome RNA genes. The endophyte isolated Fukaura ecotype was inoculated to other endophyte free genotypes. Lolitrem B contents of inoculated plants ranged from low to extremely high levels. This was thought to an interaction between the endophyte strain and plant genotype. Growth characteristics of endophyte-infected (E+) plants were investigated under low P nutrient solution culture condition. In both perennial ryegrass and tall fescue, E+ plants showed larger secondary root system. Moreover, it was clarified that an endophyte has a beneficial influence for the mineral absorption. Mineral compositions in leaf blade were high in phosphorus and sulfur of E+ tall fescue plants and in phosphorus of E+ perennial ryegrass plants. In case E+ forage plants were practically used, it is required to check toxicity of alkaloid produced by endophyte to animals. Mice have been used to clarify the mechanism underlying the toxicity of endophyte alkaloids in livestock. When seeds powder densely infected with endophyte was fed, no mice showed any signs like stagger, but showed increased body temperature and decreased rotarod performance.