Preliminary Study In The Immunity Mechanism Of Tobacco Resists Bacterial Wilt Induced By Aluminum Hydroxide

As we all know, bacterial wilt caused by Ralstonia solanacearum is the chief disease of tobacco, widespread in tropical and subtropical regions. Currently, there are many types of methods to control tobacco bacterial wilt, such as biological control, chemical control and resistance breeding, and the use of plant elicitors is a new research direction to induce the plant disease resistance. This test takes the concept of "plant immunization" into account, along with the concept of plant elicitors and uses aluminum hydroxide, which is a classical adjuvant, as an inducing agent to study its effects on tobacco to bacterial wilt.The experiments that treated Ralstonia solanacearum and seeds of Nicotiana rustica L., Gansu Yellow Flower separately with aluminum hydroxide indicated ATH had no antimicrobial effects on the growth of Ralstonia solanacearum either in solid or liquid culture medium as well as had no influence on the seed germination.The results of the screening experiment showed that the tobacco has some certain symptoms of hypersensitivity reaction under the ATH treatment; the enzymatic activity of PAL and PPO increased when the concentration of ATH changed from 20mM to 100mM, and 60mM ATH has best effects. In addition, we mixed the 60mM ATH and Tb23 of Ralstonia solanacearum together according to the proportion of one to four.In this study, we dealed Nicotiana rustica L.,Gansu Yellow Flower with different treatment, the results suggested that different treatments on tobacco could cause some certain changes of physiological and biochemical in treated leafs:enhanced activity of phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and increased contents of lignin and salicylic acid. In untreated leafs, the activities of PAL, PPO and POD rised, and the content of SA are increased by treatments separately with ATH and the mixture. The changes in leaves at different positions revealed that the signals transduction has obvious spatio-temporal differences in plant. Symptoms of tobacco bacteria wilt could be caused in the bacteria treatment group, while could not in the the mixture treatment group, in which the duration of disease resistance stayed for a longer time. The results predicted ATH could involve in plant disease resistance through a series of physiological and biochemical reactions, and in plants ATH has some sustained release effects as similar as in animals.The results indicate that aluminum hydroxide can increase the activity of defense enzymes on tobacco, trigger the immunity system, control of bacterial wilt by Ralstonia solanacearum. Therefore, ATH may represent a novel class of inducer that stimulates SA-mediated defence responses in plant.