Effect Of Arbuscular Mycorrhizal Inoculation On Cold Resistance In Tibetan Elymus Nutans Griseb

Cold stress is one of the most important abiotic stresses affecting plant growth and metabolism. Arbuscular mycorrhizal fungi(AMF) are widespread symbiotic fungi and could promote plant growth and development, and increase the ability of plant stress resistance. Here we conducted an experiment to address whether the effect of AMF on seedling cold tolerance.Two cultivars of Elymus nutans Griseb(Zhengdao and Kangma) were subjected to 5 oC cold stress for 5 d after cultivated for 45 days in the pots that were inoculated with or without Glomus mosseae(Nicolson & Gerdemann). Seedling performances were estimated by AMF inoculation rate, changes in plant morphological and physiological performances. The results were as follows:1. AMF inoculation rates was quite variable among the different E.nutans cultivars, it was significantly higher in Kangma than in Zhengdao. From 0 to 45 d inoculation rate increased steadily both cultivars, with 45 d having the highest inoculation rates, 40.67% in Zhengdao and 42.38% in Kangma. However, 45 to 60 d showed decreased AMF coloniz ation rates. As a result, 45d-old seedlings were used for cold stress experiments.2. Under cold stress, plant growth was inhibited in both cultivars. However plant shoot and root dry weight, and root scanned morphology indexes, including total root surface area, total root length, average root diameter and number of root tops, tended to be higher with AMF inoculation under cold stress, especially in the Kangma cultivar.3. To further elucidate the relationship of AMF inoculation and E.nutans cold resistence, several physiological indexes were detected. The results showed that inoculated with AMF decrease relative electrolyte leakage(REL), malondialdehyde(MDA) content, -·2O content and H2O2 content in leaves of two cultivars of E.nutans by 14.08%, 39.39%,37.33% and 11.76% in Zhengdao, and 27.91%, 66.69%, 16.48% and 15.67% in Kangma, respectively. Activities of antioxident enzyme, including superoxide dismutase(SOD), catalase(CAT), ascorbate peroxidase(APX) and glutathione reductase(GR) were increased by 54.98%, 46.61%, 62.65% and 33.07% in Zhengdao, and 37.02%, 64.54%, 85.46% and 21.74% in Kangma, respectively. And accumulation of reduced glutathione(GSH) and soluble sugar content were also increased significantly by AMF inoculation under cold stress in our research. Moreover, AMF inoculation increased the content of total chlorophyll and carotenoid significantly under organic condition.Our results suggested that AMF inoculation increased the cold tolerance in 45-day-old seedlings of Zhengdao and Kangma. The contrasting effects of changes in morphological and physiological performances of two cultivars explained Kangma appear to be more cold toleranct than Zhengdao, in any tested condition. Besides, the Kangma cultivar exhibited better adaptability to G. mosseae than the Zhengdao cultivar did.