| Rice sheath blight is a major disease in rice production and has an important impact on high yield and stable yield of rice.Due to the lack of immunity and high resistance varieties in the current production,long-term large-scale use of chemical agents to control diseases leads to increased resistance of pathogens,and the control effect is gradually reduced.In recent years,the use of inducing factors to induce plant disease resistance has achieved remarkable results in controlling rice diseases.In this study,we attempted to induce rice under the using of exogenous ethylene and jasmonic acid,to analyze the physiological and biochemical indexes related to rice disease resistance and to analyze the expression level of rice defense genes under the stress of Rhizoctonia solani.In order to provide a theoretical basis for the use of exogenous ethylene and jasmonic acid to induce rice to improve resistance and develop new methods and ideas for the prevention and control of rice sheath blight.The main results are as follows:(1)Treatment of Rhizoctonia solani with ethylene and jasmonic acid,observed the growth of hyphae of Rhizoctonia solani 24 h and 48 h,and found that both ethylene and jasmonic acid had no significant effect on the mycelial growth of Rhizoctonia solani.(2)Rice plants was treated with ethylene at four concentrations of 0.05 mmo L/L,0.1 mmo L/L,0.2 mmo L/L,and 0.4 mmo L/L,and rice plants treated with distilled water were used as controls.It was found that rice plants showed a certain induction of disease resistance.The relative disease spot height of rice plants treated with ethylene was lower than that of rice sheath blight without ethylene treatment.Among them,ethylene with the concentration of 0.2 mmo L/L had the best treatment effect,and the relative control effect was 86.17%,also the relative height of the treated rice sheath blight was significantly different from controls;the rice plants treated with 1?L/L ethylene inhibitor(1-MCP)showed that the incidence of rice plants was more serious than that of the control,and the relative disease spot height was significantly higher compared with the control.The rice plants were treated with JA at 0.01 mmo L/L,0.1 mmo L/L,0.5 mmo L/L,and 1 mmo L/L,and the rice plants were treated with that without JA solution as control.JA with the concentration of 0.1 mmo L/L had the best treatment effect,it has obvious induced resistance to rice sheath blight,and the relative control effect is 82.38%.The relative disease spot height of rice sheath blight treated with JA at a concentration of 0.1 mmo L/L has obvious difference of relative disease spot to that of jasmonic acid.Rice plants treated with 3?mo L/L jasmonic acid inhibitor(IBU)showed that the relative disease spot height of rice sheath blight was significantly higher than that of the control,and the incidence was more serious.(3)After treatment of rice with 0.2 mmo L/L ethylene and 0.1 mmo L/L jasmonic acid,the activities of POD,PAL and ?-1,3-glucanase in rice plants showed different degrees of increase,but PPO has no significant difference in activity compared with the control group,and the content of malondialdehyde after induction treatment was significantly reduced,which reduced the damage caused by rice sheath blight on the intimal system of rice plants.(4)After treating rice with 2 mmo L/L ethylene and 0.1 mmo L/L jasmonic acid,and the relative expression of PAL,POX and Os PR1 b genes in rice was determined.It was found that the expression level of PAL,Os PR1 b and POX treated was up-regulated in a certain period of time which was significantly different from the control group.(5)The increase of these plant defense enzyme activities and the increase of defense gene expression are closely related to the induction of disease resistance of rice sheath blight,which is the physiology and biochemical mechanism of resistance to rice sheath blight induced by ethylene and jasmonic acid. |
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