The Differentiation Of Citrus Bacterial Canker Disease And Screening Of Antagonistic Organism In Hunan Province

Citrus canker is a quarantine disease makes an impact on quality and yield of citrus which caused by Xanthomonas axonopodis pv. Citri. This article to take leaves of the incidence of major citrus producing areas in Hunan Province, separation and purification pathogens were identified using RCA, combined with the outcome of physiological and biochemical analysis of differentiation between the strains. The result showed that isolated strains from soil and purified antagonism strains of citrus canker is feasible.1130strains isolated from samples of six varieties of nine different regions of Hunan Province, and ultimately determine32strains of citrus canker bacteria by RCA.2Physiological and biochemical tests on32pathogens display differences on the physiological indicators like mannose, maltose, galactose, sucrose, xylose, fructose, rhamnose, and the biochemical indicators like malonate, produce indole, produce H2S, oxidase, catalase, the nitrate reduction reaction. Analysis combined with the phylogenetic tree of citrus canker pathogens, the more higher homology of the strain, the more physical and chemical properties shows similar.The distribution of the strains isolated in different regions and host species in the phylogenetic tree branch, showing the result that there is no causal relationship between the differentiation of strains and host species and the geographical distribution of strains.3347strains isolated from samples of soil of Hunan Province. The curative efficacy of the CZR1、CLT2and CLT3is prominent and all the inhibition zone reaching40mm. The reault of Pot Experimen showed the bestest control efficiency of CLT3reach83%. Observation on the morphology of the bacterial showed that CLT3was one of the actinomycetes of gram-positive, and the other two bacterial were gram-negative. The result of physiological and biochemical determination showed that the optimum growth temperature, the optimum pH and the optimum salt concentration of the three were at28℃,35℃and30℃,7.5,6and6.5,10%、5%and8%.These strains were classified into the genus of Streptomyces vinaceus, Pseudomonas aeruginosa and Burkholderia cepacia respectively.The antibacterial effect on citrus canker bacteria in vitro experimental results show that CLT3produce antibiotics, CLH2produce properties of siderophore, CZR1produce bacteriocins.