Comparative Research On Silicon And BTH-Induced Tobacco Resistant To Tobacco Bacterial Wilt

Tobacco bacterial wilt is one of the main soil-borne bacterial diseases of tobacco. It affects the production of tobacco leaf seriously, meantime threatens the benefit of tobacco farmers badly with wide occurrence and difficult to control.Tobacco farmers are forced to give up planting tobacco in some serious incidence area. Tobacco bacterial wilt has become one of the most important factors which has restrained the sustainable development of modern tobacco agriculture. At present, measures which are used to control tobacco bacterial wilt have few effects, such as rotations, resistant breeding, chemical and biological control. Actually the immune system of plant opens automatically when the pathogen infects the plant, it can resist the pathogen inflection directly and effectively by forming a natural and healthy disease resistance reaction. Plant induced disease resistance is one of the measures which can use self-resistance resources effectively, with advantages of safety, non-pollution, high and multiple resistance etc. It is also one important pathway to control the plant disease. The purpose of this paper is to identify the effects and relative mechanism of inducing tobacco bacterial wilt by BTH and Si, which can provide reliable and effective practice and theoretical basis. To achieve this, mainly by statistical analysis of the result by determining the content of bacteria in processed tobacco root, content of Si in root, stem and leaf, activity of defense enzymes in leaves, changes of resistance-related gene in leaves, and also investigating the incidence of tobacco bacterial wilt indoor and outdoor. 1. BTH and Si induced tobacco bacterial wilt resistance and have the best concentration effectAccording to preliminary evaluation of antimicrobial effect to Ralstonia solanacearum and inducing tobacco bacterial wilt by BTH and Si, result shows that BTH and Si didn’t any directly antimicrobial effect to tobacco bacterial wilt. The results of inducing resistance effect to tobacco bacterial wilt by different concentration of BTH and Si show that the best controlling effect is 68.62% and 58.77% with 1.0 mmol/L BTH and 2.3 mmmol/L Si compared to other concentration. Above all, the best concentration of inducing tobacco bacterial wilt is 1.0 mmol/L BTH and 2.3 mmmol/L Si. 2. Different effects of BTH/Si/BTH+Si to Ralstonia solanacearum in tobacco root, and content of Si in tobaccoAccording to determination of Ralstonia solanacearum in tobacco root, the bacteria content of BTH/Si/BTH+Si is 6.87/7.11/7.56 cfu/g, BTH and Si had significant controlling effect of Ralstonia solanacearum by individually application, and BTH is better. However, when BTH+Si, controlling effect is not good enough. According to determination of Si in tobacco, Si content in stem and leaf have not changed very much in 1-5 days, meanwhile differences are not significant in individual processing. For tobacco root, Si content have significant differences in individual processing. The silicon content of BTH/Si/BTH+Si/control is 4.82/7.63/6.49/5.08mg/g. When application with Si only and BTH+Si, Si content is much higher than that with BTH+Si. 3. BTH/Si/BTH+Si have significantly different effect to the physiological and biochemical of tobacco infected by tobacco bacterial wiltAccording to determination of the activity of POD/PPO/PAL/CHT and GLU, it shows that activity of POD and GLU has been strengthened significantly by Si application only, which can also regulate the resistance of tobacco bacterial wilt. The activity of PPO/PAL is 7.81/7.09 U/mg,the activity of PPO/PAL has been significantly increased by BTH application only. The activity of CHT/GLU is 3.10/58.34 U/mg, the activity of CHT/GLU has been significantly increased by BTH+Si application. GLU and CHT can be transferred into plant, and also toxic to bacteria. 4. The molecular mechanism of BTH/Si/BTH+Si inducing resistance tobacco bacterial wilt revealed in different resistance genesThis experiment determined the gene expression of PR1, PR1a/c, PR2, EFE26, ACC Oxidase and HIN1 in tobacco leaves. The results showed that gene expression PR2, EFE26, ACC Oxidase and HIN1 were significantly improved by BTH applicaiton. The gene expression of PR1,PR1a/c were not significantly improved by Si application, however it’s much lower by BTH+Si application. Through analysis, different effects of resistance tobacco bacterial wilt by BTH, Si, BTH+Si applications are mainly in the gene expression of PR1, PR1a/c. 5. BTH and Si have significant controlling effect of tobacco bacterial wilt in filed and indoor.The results in laboratory showed that the controlling effect of tobacco bacterial wilt by BTH application only and Si application only were 70.83% and 47.92%, which were 34.33% and 11.42% higher than that by BTH+Si application. The results in filed shows that the controlling effect of tobacco bacterial wilt by BTH application only and Si application only were 40% and 21.05%, which were 32.86% and 13.91% higher than that by BTH+Si application in the last investigation. Above all, it prove that BTH,Si and BTH+Si can improve the tobacco resistance of tobacco bacterial wilt. The controlling effect of tobacco bacterial by BTH is highest in the field, followed by Si application, the controlling effect of BTH+Si application is lowest in the field.