Neotvphodium Endophyte In Festucu Sinensis And Effect On Cold Tolerance To Host

Chinese fescue (Festuca sinensis Keng), a good quality forage in alpine region of Qinghai-Tibeten Plateau of China was studied, mainly including morphological diversity, phylogenetic analysis and effects of Neotyphodium endophyte infection on cold tolerance to Chinese fescue. The results summarized as followings:1. All of the Chinese fescue samples tested in the study were collected from Sangke and Ganga grassland of Gansu provience. A total of 48 endophytic fungal strains were isolated and purified from seeds. Based on the observation and measurement of the morphological characteristics of appearance of colony, conidia and conidiophores, all isolates were classified into 3 types, i.e.:13 strains of them were belonged to the morphological Neotyphodium group ZHYM-Ⅰ,20 were ZHYM-Ⅱ,15 were ZHYM-Ⅲ. A significant diversity were observed among these 48 strains in morphology.2. DNA fragment of translation elongation factor 1-αgene (tefA) introns andβ-tubulin gene (tubB) introns were cloned and sequenced. Sequences from representative strains of Neotyphodium spp. obtained from GenBank were aligned with the sequences found in this study. The preliminary results show that the isolates obtained from Chinese fescue were belonged to Neotyphodium.3. Germination testing indicated that endophyte infection could increase the germination rate, accelerate germination speed and promote growth of radicle and embryo of seeds. Especially under 10℃stress, the germination rate, germination index and length of radicle and embryo of endophyte infected F. sinensis were significantly higher than those of endophyte free seedlings (p<0.05).4. Stress experiment at low temperature indicated that, compared with the endopyte-free seedlings, endophyte infection could significantly increase tiller number and underground biomass accumulation of seedling (p<0.05), could significantly increase soluble sugar content, protein content, praline, the POD, SOD, CAT activity and maximal photochemical efficiency of PSⅡ(p<0.05), performed strong cold tolerance.5. The result of the over-wintering experiment showed that Neotyphodium endopyte infection could enhance the winter survival rate and spring re-growth capability of the plant.