Induced Resistance Mechanism In Rice Against Rice Seedling Blight Disease By Abscisic Acid

Rice seedling blight is a common disease which often occurs in field and seedling raising bed.Process of using inducer in plants can enable them to produce disease resistance.It can prevent injury on plants by pathogen and reduce residue of chemicals in agricultural and sideline products.Compared with other traditional disease control methods,it has features of low pollution,long duration and little influence on crop quality.This study explores the abscisic acid and the abscisic acid inhibitor treatment on rice seedling blight occurred in exogenous.The results can provide basis of theory and application for intense study of exfoliate acid plant inducer.Through the experiments,we found that the application of exogenous ABA can affect the growth and development of rice.In a low concentration(<0.05mmol/L),the ABA solution can promote the germination of rice seeds and improve the quality of rice seedlings,but in a high concentration,it would inhibit the growth and development of rice.Rice seeds and seedlings were treated with different concentration of ABA solution,then were inoculated with the spore suspension of Fusarium oxysporum.The results shows that ABA solution concentration can notably improve the disease resistance of rice to Fusarium oxysporum and the activity of PPO,POD,PAL and POD in rice seedlings.Also it is positively correlated with disease resistance of rice.The activity of POD,SOD,PAL and PPO was 24.50%,31.65%,46.78% and 16.78%,respectively,compared with the control group of rice seedlings treated with 0.2mmol/L ABA solution.So it means that PPO,POD,PAL and POD played a big role in process of inducing resistance to rice seedling blight and the reducing content of MDA in the leaves of rice seedlings.Also the membrane lipid peroxidation process was weakened,but the anti-damage ability of cells was improved.The rice seedlings were treated with abscisic acid inhibitors(ABAI)and then inoculated with the spore suspension of Fusarium oxysporum.The result shows that the resistance of rice seedlings which treated with ABAI and the activity of PPO,POD,PAL and POD decreased.But the content of MDA increased.So all of these prove that ABA plays a significant role in inducing the resistance of mrice.Rice seedlings were inoculated with Fusarium oxysporum after they were treated by different concentrations of ABA solution,then we collected samples at 0,24,47,72,96,120 and 144 hours after inoculation.Analyzing the resistance gene expression by qRT-PCR technique,we gain the result that the resistance genes of rice seedlings in the ABA treatment group were on the rise.The gene expression of RTBA1,RTBA3 and RTBA4 was 342.59%,437.85% and 58.25%,respectively,in the rice seedlings treated with 0.2mmol/L at 144 hours.The concentration of ABA is higher,the expression of genes of rice blight resistance is higher and the resistance to rice blight is also higher.