Isolation, Identification And Pathogenicity Study Of The Pathogenic Bacteria Of Tea Tree Anthracnos

Tea(Camellia sinensis)is widely consumed because of ITS rich flavonoids(catechins),purine alkaloids(theobromine and caffeine),L-theanine ketones and other nutrients.Tea trees as warm and humid growth environment,these characteristic areas are also conducive to the improvement of diseases of tea trees.Because tea plant diseases are primarily focused on the economic value of leaves and tea,research on tea plant diseases is primarily focused on leaf diseases.Tea anthracnose,as one of the main diseases of tea leaves,has caused serious economic losses to tea production.From March 2021 to May2022,more than 200 tea samples with typical anthracnose symptoms of 13 varieties were collected from 8tea planting bases in Guizhou and Yunnan provinces.A total of 254 strains were obtained,and 173 strains were identified to cause tea disease by Koch ’s rule.There were 73 strains of main pathogenic fungus(Colletotrichum)and 96 strains of other pathogenic fungus.The pathogenicity of 26 strains of C.camelliae 6 strains of C.fructicola 5 strains of C.kahawae 2 strains of C.gloeosporioides and 1 strain of C.siamense were analyzed.Based on the pathogenicity and stability of pathogenic strains,9 pathogenic strains were selected as representative strains of different species and different pathogenicity to determine the related pathogenic factors.The main results are as follows :(1)From the Camellia oleifera in Guiyang area of Guizhou Province,C.sinensis cv.Zhelong-117,C.sinensis cv.Longjing-changye,Fuding-white tea,C.sinensis cv.Zhelong-113,Qianmei 809,Yingshuang tea,Huangdan-Changye tea in Qixingguan District,White tea and Golden tea in Zhijin area,Tribute tea in Shiqian County,Yunwu tea in Leishan County,and Yunkang 10 in Puer City,Yunnan Province.73 strains of main pathogenic fungus and 96 strains of other pathogenic fungus were isolated from 13 varieties of anthracnose susceptible samples.Through morphological and polygenic phylogenetic analysis,73 strains of pathogenic fungus were classified into 5 species of Colletotrichum,which were C.camelliae,C.fructicola,C.gloeosporioides,C.siamense and C.kahawae,resp.ectively.Among them,59 strains of C.camelliae were the main pathogenic fungus,accounting for the largest proportion(80%)and the most widely distributed,followed by 6 strains of C.fructicola and 5 strains of C.kahawae.A total of13 varieties were collected,the pathogens of Alternaria were isolated from the diseased leaves of Camellia oleifera,C.sinensis cv.Zhelong-117,C.sinensis cv.Longjing-changye,Fuding-white tea,C.sinensis cv.Zhelong-113,White tea,Golden tea and Yun kang 10 varieties.Qianmei 809,Yingshuang tea,Huangdan-Changye tea,Tribute tea and Yunwu tea were not isolated.The other 96 strains were preliminarily classified into 21 genera by ITS nucleic acid sequence analysis,among which Irpex sp.and Clonostachys sp.were new host pathogens of tea plant diseases.(2)The 40 strains of Colletotrichum used for experimental analysis can infect Fuding-white tea and Camellia oleifera at the same time,but there are obvious differences in pathogenicity,that is,for the same host,the pathogens not only show pathogenicity differences between species,but also have pathogenicity differences within species.Through the comparison of lesion size,a total of 8 strains with weak pathogenicity on Fuding-white tea but strong pathogenicity on Camellia oleifera were screened: 3a-C-5,3a-G-1,2d-B-1,4b-A-4,8a-M-1-2,1-F,TJ-35,TJ-36;there were 9 strains with strong pathogenicity on Fuding-white tea but weak pathogenicity on Camellia oleifera: TJ-8,TJ-11,2c-B-3,2c-G,6a-O-2,7a-A-1,TJ-12,1-J,TJ-37.At the same time,there were 8 strains with strong pathogenicity on Fuding-white tea and Camellia oleifera: TJ-3,TJ-4,TJ-7,3a-I-2,2c-C-3,4b-D-3,2d-D-3 and TJ-37,among which 4b-D-3 and2d-D-3 were highly pathogenic and stable.At the same time,there were three strains with weak pathogenicity on Fuding-white tea and Camellia oleifera: 3b-P,2c-C-4 and 6a-N-3,among which 2c-C-4and 6a-N-3 had the lowest pathogenicity.The remaining 12 strains of TJ-4,TJ-7,3b-B-1,6a-M-2,8a-M-2,7a-G-1,7 a-L-1,6a-B-1,TJ-10,2d-d-3,2c-H-1,6a-N-4 showed moderate pathogenicity on Fuding-white tea and Camellia oleifera,and their pathogenicity was not significantly different.(3)C.camelliae(4b-D-3,strong pathogenicity;6a-B-1,moderate pathogenicity;2c-C-4,weak pathogenicity)and C.fructicola(2d-D-3,strong pathogenicity;TJ-10,moderate pathogenicity;6a-N-3,weak pathogenicity)were used to analyze the difference of pathogenic factors in three strains of different pathogenicity types,(C.camelliae,4b-D-3;C.fructicola,2d-D-3;C.kahawae,TJ-34;C.gloeosporioides,1-F and C.siamense,6a-N-4)were used for interspecific difference analysis.The results showed that there were significant differences in toxin content between intraspecific and interspecific strains(p <0.0001).The toxin content of strains with strong pathogenicity was higher than that of strains with weak pathogenicity.There was significant difference in cellulase activity within C.camelliae species(0.01 ≤ p< 0.05),but there was no difference among C.fructicola species(P > 0.0001).There were significant differences in Pectinase between C.camelliae and C.fructicola(p < 0.001).The activity values of cellulase and Pectinase increased with the increase of pathogenicity intensity,that is,the enzyme activity of strains with strong pathogenicity was higher than that of weak pathogenicity bacteria,but laccase did not show this characteristic,and there was no difference in laccase activity among different pathogenicity within species,but there was significant difference in laccase activity among species.