三株柑橘溃疡病生防内生细菌对脐橙感染溃疡病后几种防御酶活性的影响

防御酶活性是寄主防卫反应能力的重要指标,很多生防因子可引起植物的防御酶活性增强。在前期工作中筛选到3株对柑橘溃疡病有防治效果的内生细菌Bacillus sp.、GN222、Kosakonia cowanii GN223和Bacillus subtilis GN232,为明确其防病机理,测定了3株细菌对纽荷尔脐橙感染溃疡病菌后几种防御酶活性的影响。结果表明,在感染溃疡病菌的情况下,3株内生细菌均可不同程度地诱导和增强脐橙树体内防御酶的活性。其中内生细菌对树体多酚氧化酶(PPO)和超氧化物歧化酶(SOD)的诱导强度小于溃疡病菌对这2种酶的诱导;菌株GN222对树体过氧化氢酶(CAT)的增强作用明显强于其他菌株;菌株GN223对树体过氧化物酶(POD)的诱导作用强于其他菌株;各处理中SOD活性总体较弱。总之,待测内生细菌对脐橙感染溃疡病菌过程中防御酶具有一定的诱导作用,但酶活性变化的时间和幅度因内生菌株不同而有明显的差异。试验结果可为3株内生细菌应用于柑橘溃疡病的生物防治提供理论依据。

Effects of three endophytic bacteria with the characteristic of controlling citrus canker on the activity of several defensive enzymes in navel orange

The activity of the defense enzyme is an important index of the host defense response ability, and many biocontrol factors can cause the activity of the defense enzyme of the plant to be enhanced. In the previous work, three endophytic bacteria Bacillus sp. GN222, Kosakonia cowanii GN223 and Bacillus subtilis GN232 with control effect on citrus canker were selected. To clarify the control mechanism, the effects of three bacterial strains on the activities of several defensive enzymes in Newhall navel orange infected by Xanthomonas citri pv. citri were determined in this experiment. The results showed that three endophytic bacteria could induce and enhance the activity of defensive enzyme in navel orange trees which were infected by Xanthomonas citri pv. citri. The induction intensity of endophytic bacteria to polyphenol oxidase (PPO) and superoxide dismutase (SOD) was lower than that induced by Xanthomonas citri pv. citri, the enhancement effect of strain GN222 on catalase (CAT) was significantly stronger than that of other strains, the induction effect of strain GN223 on peroxidase (POD) was stronger than that of other strains, and the activity of SOD was weaker in all treatments. In a word, endophytic bacteria to be tested have a certain inducing effect on defensive enzymes in the process of navel orange infected by Xanthomonas citri pv. citri, but the time and range of enzyme activity increased variously with different bacterial strains. The results could provide a theoretical basis for the application of three endophytic bacteria in the biological control of citrus canker.