内生真菌对醉马草白粉病抗性的影响

Effects of the Epichloё gansuensis endophyte on the disease resistance of drunken horse grass to powdery mildew

为研究内生真菌对醉马草白粉病抗性的影响,在温室条件下,对自然发生不同程度白粉病(健康、轻度感病和重度感病植株)的带内生真菌(E+)和不带内生真菌(E-)的醉马草植株的发病率、病叶率、病情指数及各项生理生化指标进行测定。结果表明,E+醉马草的发病率48%显著低于E-醉马草的发病率97%(P<0.05),E+的病叶率60%显著低于E-醉马草病叶率86%(P<0.05),E+醉马草的病情指数为50.76,E-醉马草的病情指数为82.49;通过各项生理生化指标的测定发现与健康植株相比,在轻度和重度发病植株中,内生真菌的存在可以显著(P<0.05)提高醉马草叶片的叶绿素含量和脯氨酸含量,E+醉马草的SOD酶活性和POD酶活性也显著高于E-醉马草,同时内生真菌显著地降低了醉马草叶片中丙二醛(MDA)的含量。据此说明内生真菌的存在能够提高醉马草抗白粉病的能力。

Previous studies have shown that endophytes can increase the resistance of drunken horse grass (Ach-natherum inebrians )to many stresses,such as insects,diseases,waterlogging,drought,salt,and heavy met-als.The aim of this study was to compare the resistance of endophyte-infected (E+ )and endophyte-free (E- ) drunken horse grass to powdery mildew (Blumeria graminis ).Forty pots of drunken horse grass (20 E+plants and 20 E- plants)were grown in a greenhouse.After 2 months,the natural infection rates,the percent-age of diseased leaves,and the disease indexes of powdery mildew in both E+ and E- plants were estimated and recorded.At the same time,the E+ and E- drunken horse grass plants were scored as healthy,slightly dis-eased,or severely diseased based on a disease index.Then,four replicates of E+ and E- plants were randomly selected to measure several physiological indexes;chlorophyll content,activities of superoxide dismutase (SOD)and peroxidase (POD),and the contents of malondialdehyde (MDA)and proline (Pro).Chlorophyll content was measured by acetone extraction,SOD and POD activities were evaluated using nitroblue tetrazoli-um and guaiacol assays,respectively,and MDA and Pro contents were determined using the sulfosalicylic acid and glucosinolate barbituric acid methods,respectively.The disease infection rate,the percentage of diseased leaves,and disease indexes of E- plants were 97%,86%,and 82.49,respectively,significantly higher (P <0.05)than their respective values in E+ plants (48%,60%,and 50.76).The chlorophyll and proline contents and SOD and POD activities were higher in E+ plants than in E- plants,regardless of whether the plants were slightly or severely infected.The MDA content was significantly (P <0.05 )lower in E+ plants than in E-plants.These results provide evidence that endophyte infection can increase the resistance of drunken horse grass to powdery mildew disease.