The Mechanism Of Resistance To S.sclerotiorum By Expressing Oxalate Oxidase Gene In Arabidopsis

The malignant disease is caused by the genus S.sclerotiorum, have a greater influence on crop growth and development, especially its onset usually in flowering, will significantly reduce crop yields, making huge losses to the agricultural economy. S.sclerotiorum secrete oxalic acid as its primary toxic factor, and oxalic acid plays various roles in the process of S.sclerotiorum interacted plant. Oxalate oxidase could increase plant resistance to Sclerotium disease and breakdown oxalic acid to H2O2 and CO2,it has got a lot of research evidence to support. Although by genetic engineering technology, oxalate oxidase has been transformed into many crops to improve resistance to disease, S.sclerotiorum and host interaction mechanisms are still not broken through. On the study association of oxalate acid leading to programmed cell death process, found oxalic acid can induce cellular ROS level increasing, when ROS levels is inhibition and apoptosis phenomenon is disappeare. On the contrary, oxalate defects non-pathogenic is not able to alter host cellular redox levels. Plants themselves have antioxidant enzyme systems such as SOD, CAT, POD etc, scavenging excessive reactive oxygen species, protects cells from oxidative damage. But the current report focused the signaling pathways while S.sclerotiorum and host plant interaction, the effect to oxidation enzymes reported is less, that’s the reason we choice the influence to antioxidant enzymes of Arabidopsis while S.sclerotiorum infected. This experiment uses pure oxalic acid oxidase in Arabidopsis, with activity of OxO and has good disease-resistance of transgenic T4 in Arabidopsis. Through treatment with S.sclerotiorum, oxalic acid, sodium oxalate, hydrochloric acid and other different conditions, compared the expression and enzyme activity of antioxidant enzyme system SOD, CAT and POD in wild-type Arabidopsis thaliana and transgenic Arabidopsis thaliana. And investigated S.sclerotiorum disease dependent on oxalic acid and get the following three conclusions:1) This experiment analysised the different between wild-type and transgenic Arabidopsis leaves of SOD, CAT and POD genes expression levels and enzyme activity while under different treatment conditions. Showed when S.sclerotiorum infected Arabidopsis thaliana or when treatment with exogenous oxalic acid, will suppress the expression and activity of SOD, CAT enzymes, but facilitating POD.2) This experiment showed that oxalate oxidase could ease of inhibition on SOD and CAT enzyme by S.sclerotiorum or OA, which showed that the role of oxalate oxidase is played by degradation of oxalate.3) Through this experiment, HCl is used to instead of oxalic acid in liquid secreated by S.sclerotiorum, and successful made disease spot, indicating S.sclerotiorum pathogenicity is dependent on acid, HCl can be used instead of oxalic acid to restore the virulence of S.sclerotiorum.