Research On The Bacterial Community In The Gall Tissue Of Cryptomeria Fortunei And Their Pathogenicity

Cryptomeria fortunei, one special tree species in China, has important ecological and tourism value. C. fortunei mainly distributed in Tianmu mountain and surrounding areas in Zhejiang province. At present, the gall disease on C. fortunei has become a serious threat to the ecological safety and landscape in Tianmu mountain. The incidence rate of this disease reached to 90%. In order to clarify the disease, bacteria in the tissue of the gall and their pathogenicity had been studied in this research and the main results are listed as following:1. Investigation of the gall disease of C. fortunei at the Tianmu mountain showed the incidence rate of gall reached to 97%. The number of galls on the tree varied with the plant age and growth. At the earlier stage, the surface of the gall exhibited faded green, raised and smooth. Then, the gall became rough and black on the crack surface. In the mean time, the leaves of the plants infected with this disease reduced significantly and chlorophyll synthesis became slow at early onset, then the branches began to appear wilt symptom. At the last, the plants died.2. The isolation of bacteria from the gall tissue was performed. The results showed that two kinds of bacteria existed in the tissue mainly, which were Pseudomonas and Erwinia. The population of the bacteria belonging to Pseudomonas spp and Erwinia spp.was 8.12×105 CFU/g and 3.33×105 CFU/g, respectively.3. These bacteria were used to test the pathogenicity on C. fortunei. The results showed CF01 can cause gall on the plants and the incidence rate reached at 14.3%~35.7%. The bacteria belonging to Erwinia spp. did not cause the gall. Inoculation with the bacterial mixture of Pseudomonas and Erwinia could enhance the incidence rate to 15.1%~40%. It could be deduced that CF01 was one of the causes of the gall disease.4. The physiological and biochemical characteristics of CF01 were tested. Biolog Test results showed that CF01 can utilize 37 carbon sources but the other 34. In addition, CF01 was sensitive to 16 kinds of chemical substances. The whole genome of Pseudomonas sp. CF01 was sequenced. The draft genomic sequences were obtained. Interestingly, this bacterium could produce the IAA(4mg/L), which is a plant hormone. It is speculated that this bacterium caused the gall of C. fortunei by producing IAA.5. In the last, we test 6 bactericides and several bacteria for antagonizing CF01. The results showed that simeimycin has the highest activity agaist CF01.The bacericides zhongshengmycin and streptomycin showed less activity. Paenibacillus polymyxa also showed significant antagonic activity against CF01.