Studies On The Role And Mechanise Of Polyamines In Enhancing The Resistance To Citrus Canker Disease

Citrus canker is one of the most serious bacterial diseases which cause serious damage to the citrus industry and economic. Studies have shown that polyamines play an important role in plant disease resistance responses. But reports about the role of polyamines in citrus disease response is very limited. In this paper, a highly susceptible variety(Citrus sinensis cv. Dahong cheng) is used as experimental material. The relationship of endogenous polyamine contents in the leaves and exogenous polyaminesn under different temperatures was studied. And on this basis, the relationship between polyamine and orange citrus canker resistance was explored. The main results are as follows:1.the relationship between the temperature and citrus canker resistance inoculated citrus canker on candy orange which treated at21℃and30℃3days respectively.7days after the inoculation, the morbidity rate and disease index of plants teated at21℃were lower than30℃. But there is no significant difference between them for the time onsetfa2. The relationship between the temperature and the polyamine content in the leaves:the polyamine content in the leaves were measured after3days after treatment at21℃and30℃respectively. Three kinds of free polyamine content (Put, Spd, Spm) were significantly lower at30℃than the21℃.3. The relationship between the endogenous polyamines content and exogenous polyamines:The plants were sprayed with0.4mmol/L Put and Spd solution, and the endogenous polyamines content was compared with the control group which was sprayed with water after72hours. The exogenous Put and Spd solution could enhance the content of the endogenous Put and Spd. Semi-quantitative detection of polyamine biosynthesis related genes proved that these genes are very activly.4. The relationship between the exogenous polyamines and citrus canker resistance:sprayed the plants with0.4mmol/L Put and Spd solution, and then inoculated the citrus canker bacteria after72hours. Exogenous polyamines could slow down the onset time effectively in the leaf and reduce the degree of the disease. Analysised the expression of disease resistance related gene and found that polyamines can induce the AOS genes and GPX gene.