| Potato is one of the world’s four major food crops after rice, wheat, and maize. China is one of the world’s largest production bases of potato. Potato late blight which is caused by Phytophthora infestans is a devastating disease in potato production, and widespread around the world and causes severe damage. Up to now, potatop late blight has been listed as the first food crop diseases all over the world. The effective control of potato late blight has become a serious problem to be solved urgently at present. With the development of agricultural technology and the growing awareness of environmental issues concern, the use of activate natural plant defense mechanisms to combat plant disease has become a hotspot in the field of plant pathology. In recent years, the induced resistance to potato late blight by a variety of biological sources and non-biogenic elicitors has been reported successively, but there was little knowledge about complex elicitor that could induce resistance in potato to late blight.This study was based on the results obtained by inducing resistance in potato tuber slices against late blight with microbial elicitors in the previous experiments in our laboratory. The induction conditions of actinomycetes A5295 strain, with induction efficiency of 63.97%, for inducing potato tuber slices to late blight, was optimized, and the screening model of selecting elicitors was established in this experiment. Both single type elicitors and compound type elicitors, which could significantly enhance resistance in potato tuber slices against late blight were compared and screened according to the established screening model. And then changes of resistance-related enzyme activities and soluble protein content were measured and analyzed in potato tubers induced by elicitors. In addition, the best compound elicitor was used for inducing resistance in carrot root tuber and sweet potato tuber, and obtained good protection effeiciency.The main results were as follows:1. Optimized a variety of induction conditions of actinomycetes A5295 for inducing potato tuber slices to late blight. The induced efficiency was up to 75.71% with optimal induction conditions. Based on optimal induction conditions, a screening model of single type elicitors was established in inducing potato resistance to late blight. By using this model, 9 elicitors with induction efficiency over 70% were obtained, and all of them were single microbial fermented filtrate.2. A screening model of compound type elicitors was established in inducing potato resistance to late blight. The induction efficiencies of compound type elicetors were compared and screened by mix four elicitors (A5295, NB7 and YH2, and A206) in pairs with same volume ratio. A compound elicitor with induction efficiency 83.45%, combined A5295 with A206, was obtained among them. And then the best induction efficiency was found in mixture of volume ratio as 2:1, combining A5295 and A206 fermentation liquids, and the induction efficiency reached 86.39%.3. The changes of resistance-related enzyme activities (PPO, POD, PAL, SOD) were understood in potato tubers induced by compound elicitors (A5295 and A206). All the activities of POD, PPO, PAL , SOD in potato tubers induced by elicitors were significantly higher than that in control group. Especially the activities of POD, PPO, PAL, SOD in tuber slices induced with elicitor and inoculated with P.infestans increased by 93.2%, 74.0%, 90.0%, and 13.2%, respectively. And these changes were positively correlated with disease resistance of potato tuber slices to late blight, the disease index in control group is 91.86%, and the disease index in induced with elicitors is 13.45%, the induced efficiency after induction is 85.36%.4. The changes of soluble protein contents were analyzed in potato tubers induced by the compound elicitor. And the expression of proteins in tuber slices induced by compound elicitors were significantly increased by 90.3% in comparison with control, and the number of bands in tuber slices induced with elicitor and inoculated with P.infestans increased by 5-7. And these changes of protein bands were positively correlated with disease resistance of potato tuber slices, the disease index in control group is 91.86%,and the disease index in induced with elicitors is 13.45%, the induced efficiency after induction is 85.36%.The increased protein bands, about 3-4, were between 20-40KD, and speculated as the PR proteins.5. The resistances in potato tuber slices to ZX12 and Rhizoctonia solani were obtained by using compound elicitor. The induction efficiencies in tuber slices against two species of pathogenic fungi were 54.71% and 72.40%, respectively.6. The resistance in carrot root tuber and sweet potato tuber against Rhizoctonia solani was effectively enhanced by using compound elicitors. The induction efficiencies in carrot and sweet potato against fungus were 56.22% and 43.81%, respectively. |
PDF Full Text Request