Mechanism of symbiosis between Neotyphodium endophyte and grass species

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This study was to clarify the mechanism of symbiotic relations between Neotyphodium endophytes and grass species through incidence of endophyte infected plants(E+) in Northern Japan, change of E+ plants frequency, effect of fungicides to E+ plants, and characteristics of E+ plants for compatibility and mineral uptake.The incidence of endophytes investigated for naturalized perennial ryegrass and tall fescue plants collected from northern Japan. Percentages of infected plants were 10% in perennial ryegrass and 15% in tall fescue. Average ergovaline concentrations in seeds were 1.86ppm and 6.27ppm in perennial ryegrass and tall fescue, respectively. Average lolitrem B concentration in perennial ryegrass was 1.41ppm. Concentrations of alkaloids differed markedly among the collected plants. Change of E+ plants frequency differed depending on sites, and the frequency rose greatly in turf developed at riverside, High temperature, dry condition, and sandy soil affected to the frequency of E+ … More plants. To create E-from E+ plants, kind of fungicides and the treatment conditions were tested. The fungicide benomyl was effective in killing endophyte in both perennial ryegrass and tall fescue. triforine was effective only in tall fescue, and thiophanate-methyl had little effect. These results indicate that interactions exist between these fungicides and Neotyphodium spp. The accuracy and reliability of immunoblot detection kit was examined. Results obtained by both methods were similar. Compatibility of E+ was tested with or without the companion crop, white clover. Difference between E+ and E-of perennial ryegrass was found under mixed planting with white clover. The effects of physico-chemical properties of Andisols on tall fescue ecotypes E+ and E-were compared. E+ plants showed vigorous growth and agronomic efficiency of water use than the non-infected plants grown in Black Andisol while opposite trend was observed in Red Andisol. Growth characteristics of endophyte-infected plants were investigated under low P nutrient solution culture condition. In both perennial ryegrass and tall fescue, E+ plants showed high grass height and larger secondary root system. Less