Responses Of Epichlo? Gansuensis-Achnatherum Inebrians Symbiont On Stresses Of Cold And Powdery Mildew Disease Treated By SA And ABA

Achnatherum inebrians is a perennial grass infected by fungal endophytes of Epichlo?, has many advantages on tolerance e.g. salt, drought, heavy metal, disease, insect, cold. In this study, endophyte-infected(E+) and endophyte-free(E-) seeds and seedlings of A. inebrians were tested under the stresses of cold disease. Under 10℃, seed germination and seedling growth of E+ and EA. inebrians were examined when salicylic acid(SA) or abscisic acid(ABA) were applied. The physiological indexes of E+ and E- were determined when treated with exogenous SA or ABA at 5℃. The resistance of powdery mildew(Blumeria graminis) between E+ and E- A. inebrians were determined as well. The mains results were as follows:1. Under the stress of 10℃,the germination rate, germination index, seedling water content, shoot and root lengths were determined when treated with different concentrations of SA or ABA. SA or ABA could improve the germination vitality of E+ and E- A. inebrians. Only higher concentrations of SA or ABA showed inhibition(P<0.05), highest concentrations of ABA showed strongest(P<0.05) inhibition. The interactions of SA and Epichlo? endophyte had significant(P<0.05) effects on germination rate, germination index and root length. The interactions of ABA and Epichlo? endophyte had significant(P<0.05) effects on germination index, seedling water content, shoot and root lengths. In a word, the interactions of a certain concentrations of SA or ABA and Epichlo? endophyte could promote the germination of A. inebrians.2. Under the stress of 5℃, the physiological and biochemical indexes were determined when treated with 1.5 mmol/L SA and 0.1 mmol/L ABA. The results showed that SA and ABA could increase the contents of chlorophyll, proline, soluble sugar and vitality of superoxide dismutase and peroxidase, and reduced the content of malondialdehyde. The interactions of SA and Epichlo? endophyte had significant(P<0.05) effects on proline content and vitality of superoxide dismutase. The interactions of ABA and Epichlo? endophyte had significant(P<0.05) effects on proline content, chlorophyll content, vitality of superoxide dismutase and peroxidase. In a word, the interactions of SA or ABA and Epichlo? endophyte could alleviate the injury of low temperature on seedling of A. inebrians.3. Under the stress of natural infection of Blumeria graminis, the disease indexes, physiological and biochemical indexes were determined of E+ and E- A. inebrians. The results showed that the infection rate of plants, infection rate of leaves and disease index of E+ was significantly(P<0.05) lower than that of E- A. inebrians. Epichlo? endophyte could increase the contents of chlorophyll and proline, and vitality of superoxide dismutase and peroxidase, while reduce the content of malondialdehyde. In a word, endophyte infection could improve the resistance of A. inebrians on powdery mildew.