Primary Studies On Screening And Mechanism Of Chemical Resistance Inducer For Tobacco Bacterial Wilt

Tobacco bacterial wilt is one of main diseases of tobacco in south China due toits wide occurrence and difficultly being controlled. In some place, people are forcedto stop planting tobacco. Tobacco bacterial wilt has become the most important factorwhich restraint sustainable development of tobacco. At present, the control measuresof tobacco bacterial wilt, such as rotations,resistant breeding,chemical andbiological control, because of a great variety of reasons, have no obvious effect. Theinduced disease resistance of plant is one of the measures to effectively utilizeresistance resources in plant, so it has great value of application and practicesignificance to plant disease control. Being advantages of the resistance to multipledisease, high resistance, and security in plants, it is regarded as important pathway tocontrol plant diseases.The primary objectives of this study were: (1) Provide a foundation fordeveloping mixture by elemental screening the stress resistance inducers. (2) Offer acertain theoretical basis for development of inducers by physiological andbiochemical analysis of tobacco and studying of inducing resistance mechanism.The strain of Ralstonia solanacearumn Ps570 was adopted to inoculate vitroleaves of tobacco. Use the tobacco G80 as testing material to screening inducers thatwas reported. 33 kinds of inducers were screened by sprarying them to tobacco. Takemethod of inhibiting zones to test the inhibited activity of agrochemicals. Chooseorthogonal experiment to optimize W inducing treatment conditions.Use physiologicand biochemical index to discuss induced resistance mechanism.It is better and more quick to adopt vitro leaves inoculation for testing the effectsof induced resistance.Experimental results of 33 medicament indicate that P,W,AE,AG1,AB-1,005,004 and AB-2 had no direct inhibiting effect on Ralstonia solanacearum in vitro.The effects of induced resistance were all over 30%, the highest effect of inducedresistance reached 50.8%.The best condition of W inducing G80 to obtain resistance is that W was spraiedthree times (one time every 72hrs) at temperature 28℃, when concentration of W isdiluted 400 times.It shows that W could increase the activities of POD, PAL and PPO, and littleinfluence on the activities of CAT,SOD and the contents of MDA,H₂O₂. After inoculation with Ralstonia solanacearumn Ps570, the H₂O₂ metabolism and theactivities of these enzymes above in W-treated tobacco were higher than water-treatedtobacco. W could also induce the MDA content.The results suggest that the increased activities of these enzymes and the inducedMDA content is most likely to be associated with the development of inducerresistance in tobacco seedlings.