Mechanism of symbiosis between Neotyphodium endophyte and grass species

本研究从内生真菌侵染植物(E+)在日本北部的发生情况、E+植物频率的变化、杀菌剂对E+植物的影响以及E+植物的亲和性和矿物质吸收特性等方面阐明了内生菌与草种共生关系的机制。多年生黑麦草和高羊茅的侵染率分别为10%和15%。多年生黑麦草和高羊茅种子中麦角镰刀碱的平均含量分别为1.86ppm和6.27ppm。多年生黑麦草中Lolitrem B的平均浓度为1.41ppm。在采集的植物中，生物碱的浓度差异很大。E+植株频率的变化因地点不同而不同，河滨、高温、干旱、沙质土壤条件下草坪E+…频率上升幅度较大更多的植物。为了从E+植物中产生E-，对杀菌剂的种类和处理条件进行了试验。杀菌剂苯菌灵对多年生黑麦草和高羊茅的内生真菌均有较好的杀灭效果。三福林仅对高羊茅有效，甲基托布津对高羊茅影响不大。这些结果表明这些杀菌剂与新伤寒沙门氏菌之间存在相互作用。对免疫印迹检测试剂盒的准确性和可靠性进行了检验。两种方法得到的结果是相似的。E+的亲和性在有或没有白三叶的情况下进行了测试。在白三叶混播条件下，多年生黑麦草的E+和E-存在差异。比较了阳离子土壤的理化性质对高羊茅生态型E+和E-的影响。E+植株生长旺盛，水分利用效率显著高于对照植株，而红安地松植株表现出相反的趋势。在低磷营养液培养条件下，研究了内生真菌侵染植株的生长特性。在多年生黑麦草和高羊茅中，E+植株都表现出较高的草高和较大的次生根系。较少

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