エンドファイト特性を利用したライグラス類への環境抵抗性の付与

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Neotyphodium endophyte produces animal toxicoses, and on the other hand, gives desirable traits including resistance to insects and to drought. This study was to utilize the characteristics of endophyte into grass breeding.To begin with, endophyte infection rate was investigated for perennial ryegrass ecotypes collected from highlands in German Alps and Kitakami highland by 1990. Any endophyte was not observed in both ecotypes. This indicates that endophyte does not contribute to cold resistance.Endophyte infection rate was investigated for marketed forage seed of perennial ryegrass and tall fescue. Through these two species, there was great difference among cultivars. Compared cultivars between their use, endophyte infection rates were higher in turf type than in forage type. Compared cultivars among countries originated, US cultivars indicated highest infection rate, followed by European cultivars, and Japanese cultivars were lowest.Five perennial ryegrass cultivars and three tall fe … More scue cultivars originated in Japan were all free from endophyte, and the infection rates were all 0.0%. Individual plants with endophyte must be excluded from in the process of selection. Plants with endophyte may be less adaptable under wet weather condition like in Japan.Ryegrass straw and fescue straw caused animal disorder at Morioka and other places showed high concentration in these alkaloids. Some tall fescue straw marketed in Iwate prefecture indicated higher ergovaline concentration than threshold level of animal disorder. There are some cases that animal disorder occurred in Japan under the threshold level. This may mean that the threshold level in Japan is lower than that in USA.Endophyte infected plants are low adaptable under Japanese weather condition. Then, the infection rate was investigated under practical conditions. In these cases, as golf courses, grass seeds were over-seeded on turf where ground coverage by grasses was worse, endophyte infection rates were low. However, when grass seeds were seeded newly on bare ground in sports ground, the rate was high in perennial ryegrass although that was 0% in tall fescue.Use of genetically improved turf-grasses containing useful endophytes is of great value. To use endophyte characteristics for forage crop breeding, more knowledge including difference of growth rate between plants and endophyte fungi are needed. Less