Preliminary Study On The Mechanism Of Inhibiting The Sulfone Candidate Drugs Of Rice Bacterial Leaf Blight

Rice bacterial leaf blight is vascular bundle disease caused by Xanthomonas oryzae pv. oryzae(Xoo). Up to now, there are still no pesticides controlling this disease effectually. Therefore, screening the compounds which can inhibit the pathogen is pressing.Sulfone derivatives containing 1,3,4-oxadiazole moieties indicated good antibacterial activities against rice bacterial leaf blight caused by the pathogen Xoo. In particular, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole and 2-(methylsulfonyl)-5-(4-fluorobenzyl)-1,3,4-oxadiazole revealed the best antibacterial activity against Xoo, with a half-maximal effective concentration(EC50) of 9.89 and 1.07 μg/mL, which was better than those of the commercial agents of bismerthiazole(92.61 μg/m L) and thiodiazole copper(121.82 μg/m L).Meanwhile, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole and 2-(methylsulfonyl)-5-(4-fluorobenzyl)-1,3,4-oxadiazole stimulate the increase in superoxide dismutase(SOD) and peroxidase(POD) activities in rice, causing marked enhancement of plant resistance against rice bacterial leaf blight. Moreover, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole, at a concentration of 20 μg/m L, could inhibit the production of extracellular polysaccharide(EPS) with an inhibition ratio of 94.52% and 100%, and reduce the gene expression levels of gumM, with inhibition ratios of 86.76% and 95.37%, respectively.