Distribution, usefulness, and host specificity of grass endophytes

禾草内生菌感染后，植物对某些昆虫和植物病原体的抗性增强，在农业上的利用受到重视。为了在农业上利用内生菌，应在日本和国外收集各种内生菌，然后对所收集的内生菌进行分离、鉴定和检验，以提高对昆虫和植物病原体的抗性。特别是植物与内生菌的特异性是其他植物人工接种真菌内生菌感染时的瓶颈。因此，研究的重点是在电子显微镜下相容性和不相容性的特异性。结果表明：1)不仅采集到无症状内生菌（Neotyphodium），还采集到柱头形成内生菌（Epichloe），在C4植物和C3植物中还采集到真菌内生菌；2)在C3和C4植物中都明确了内生菌侵染植物增强了对某些昆虫的抗性。3)建立了一种真菌内生菌免疫电镜检测方法。4)免疫电镜分析表明特异性表达的细胞间基质来源于寄主植物而非内生菌丝。5)用能量过滤电镜比较了相容组合和不相容组合的细胞间基质含量。结果表明，两种组合在O和P的检测等方面存在较大差异。根据这些结果讨论了宿主特异性的机制。

Grass endophytes have been paid attention to utilize in agriculture, because the endophyte-infected plants enhance the resistance to the certain insects and plant pathogens. In order to utilize the endophytes in agriculture, various kinds of endophytes should be collected in Japan and from over seas, thereafter collected endophytes should be isolated, identified and examined the usefulness such as enhancement of resistance to insects and plant pathogens. Especially the specificity between plant and endophyte is a bottleneck when the other species of plants are infected by artificial inoculation with fungal endophytes. Therefore, the researches have been forcused on the specificity of compatibility and incompatibility by using electron microscopy.The results are as follows, 1) Not only symptomless (Neotyphodium) endophytes but also stigma-formed **e (Epichloe) endophytes were collected and identified, also fungal endophytes were collected from C4 plants as well as C3 plants, 2) It has been clarified in both C3 and C4 plants that endophyte-infected plants enhanced the resistance to the certain insects. 3) A detection method for the fungal endophyte by immuno electron microscopy was established. 4) It was suggested that the contents of intercellular matrix where the specificity was expressed were derived from host plant rather than endophyte hyphae by using immuno electron microscopy. 5) The contents of intercellular matrix were also compared between compatible and incompatible combinations by using energy filter electron microscopy. As the results, there were large differences between both combinations on the detection of O and P and so on. The mechanisms of host specificity were discussed from these results.