Abstract:

In order to discuss the effect of black rot (Xanthomonas campestris pv. Campestris) on the morphological and physiological property of cauliflower (Brassica oleracea L. var. botrytis) seedlings roots, and provide evidence for establish a new root breeding method of cauliflower resistance to black rot, a serious of root morphological and physiological changes of cauliflower seedlings infected by Xanthomonas campestris pv. Campestris were studied. The results of the experiment showed that root length, root dry weight, above-ground parts dry weight and root activity increased significantly 7 DAI (days after inoculation) compared with those of 2 DAI in two treatments. Root length, root dry weight and above-ground parts dry weight in inoculated plants were significantly lower than those in non-inoculated plants. However, root activity in inoculated seedlings was significantly higher than that in non-inoculated seedlings. There was higher soluble protein concentration in roots of cauliflower under inoculation than that under non-inoculation 3 DAI; SOD activity in inoculated plants was strikingly lower than that in non-inoculated plants during 0-4 DAI, and then significantly higher than that in non-inoculated plants 5-7 DAI; PPO activity and ABA concentration in roots were significantly elevated by inoculation. However, POD activity in roots was not elevated by inoculation. The results indicated that black rot caused root morphological changes of cauliflower seedlings, and induced activities of defense enzymes and regulated endogenous hormones, such that the plant had better resistance to black rot and prevent invasion of the pathogen.