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Poster: Biology & Disease Mgmt: Bacteriology


Impacts of abundance of Candidatus Liberibacter on the citrus phyto-microbiome
R. BLAUSTEIN (1), J. Meyer (1), A. Conesa (2), G. Lorca (2), M. Teplitski (1) (1) Soil and Water Science Department, University of Florida, U.S.A.; (2) Microbiology and Cell Science Department, University of Florida, U.S.A.

Understanding how the citrus microbiome is affected by (and impacts) Huanglongbing (HLB) may be critical to disease management. To test the hypothesis that phyto-microbiome composition and diversity are related to the prevalence of Candidatus Liberibacter, the HLB-causative agent, leaves were collected from HLB-infected Valencia trees that differed in the extent of disease symptoms and the leaf-associated microbial communities were characterized by sequencing the V4 region of 16S rDNA. Approximately 1,900 OTUs were detected, representing 215 genera. The relative abundance of Candidatus Liberibacter, which ranged from 0.7 - 71.3%, induced PCA clustering and negatively correlated with alpha diversity, as indicated by Shannon (p<0.001) and Chao1 (p=0.001) indices. Positive interactions or co-occurence (p<0.05) of Candidatus Liberibacter with other genera were detected only with Pseudomonas and an unclassified genus of Oxylobacteraceae. These two, in turn, had negative interactions (p<0.05) with 5 genera that formed a complex network of positive interactions with 39 other genera, which likely represent the “healthy” phyto-microbiome. These interactions suggest that (1) the impacts of Candidatus Liberibacter on the microbiome are likely mediated through its key interactions with pseudomonads and oxylobacteria and/or (2) antagonistic effects of the bacteria from the core citrus microbiome on these two groups may lessen the pathogen titer and mitigate disease progression.