Inhibitory Effect of Catechin against Xanthomonas campestris

PurposeTo develop the application of catechin in agriculture field, so as to provide a natural microbicide model and theoretical foundation for prevention and control of cruciferae black rot, the inhibitory effect of catechin on Xanthomonas campestris pv. campestris (Xcc) should be study.

MethodThe inhibitory effect of catechin on Xcc was preliminarily determined by K-B filter paper method, and the minimum inhibitory mass concentration (MIC) and minimum bactericidal mass concentration (MBC) of catechin on Xcc were further determined by liquid dilution method. Under the subinhibitory concentration of catechin: the formation of Xcc biofilm was detected by crystal purple staining, the secretion of Xcc extracellular enzyme was analyzed by biochemical methods on the corresponding solid medium, and the mobility of Xcc was detected on swarming medium. The control effect of catechin against black rot on radish was tested in vivo.

ResultThe MIC value was 20 μg/mL and MBC value was 100 μg/mL. At a subinhibitory mass concentration of 15 μg/mL catechin: the amount of biofilm produced by Xcc was only 16% that of the negative control, indicating that catechin could extremely significantly inhibit the formation of Xcc biofilm under this condition (P<0.001). It extremely significantly inhibited the secretion of Xcc extracellular protease (P<0.001), and the production of protease secreted by Xcc under the action of catechin was only 18% to the control. But it had no effect on the secretion of extracellular amylase and cellulose (P>0.05). It had an extremely significant inhibitory effect on swarming capacity of Xcc (P<0.001). After the action of catechin, motility was weakened, which was 73% of the control. When using catechin, the degree of disease on white radish slices was low.

ConclusionCatechin can inhibit the growth of black rot pathogen and affect some virulence factors of this bacterium, and it has significant prevention and control effect in vivo assay. It is expected to provide a reference for the synthesis of new agents on black rot.