The Polymorphism Of Endophytic Bacteria Community Structure In Huanglongbing Pathogen-Infected Citrus

Studies on the incidence of citrus Huanglongbing in Shunchang County, Fujian Province, citrus Huanglongbing pathogen identification, citrus endophytic community structure and their correlation with citrus Huanglongbing pathogen were carried out. The results showed the incidence of citrus Huanglongbing was0.29%in Shunchang investigated in16plants with the yellowing symptoms on5600plants of Citrus grandis Osbeck cv. Chandler. Nested-PCR analysis indicated that the citrus Huanglongbing pathogen caused Chandler’s yellowing symptoms. This demonstrated that the occurrence of citrus Huanglongbing had a certain incubation period.The16S rDNA sequence analysis of citrus Huanglongbing pathogen blasted in the NCBI showed that Shunchang citrus Huanglongbing pathogen was Candidatus Liberibacter asiaticus.26isolates from HLB-affected citrus plants belonged to19bacterial species in10Genus. Among the bacterial populations, Bacillus pumilus (FJAT-10074) and Bacillus sp (FJAT-10067) were significantly negatively correlated to HLB bacterium. The correlations among the bacteria from the same tissue such as the leaves, sticks and roots were significantly positive, while the correlations among the bacteria from the different tissues were negative.The PLFAs was detected by MIDI system to get the biomarkers and to calculate the endophytic community diversity. The results showed that42PLFAs biomarkers were detected. It showed that citrus plants as a micro-ecological system, as health surviving environment for bacteria, were highly positive correlation. Plant as micro-ecological systems provided habitat of endophytic bacteria. This micro-ecosystem came from interactions among different microbial populations and the establishment of a dynamic ecological balance. By PLFAs (phospholipid fatty acid) markers in different parts of Citrus,42fatty acid biomarkers were detected in different leaves. The content of endogenous microbial PLFAs in citrus leaves of different orientations was significantly different. There were differences in citrus leaves of different height and different health status, but the difference was not statistically significant.