This Is AuburnElectronic Theses and Dissertations

Community Dynamics of the Phyllosphere Microbiome




Brokaw, Destiny

Type of Degree

Master's Thesis


Entomology and Plant Pathology


The phyllosphere of a plant creates a complex niche for inhabiting microorganisms in which interactions will occur. The dynamics of the interactions between a foliar plant pathogen, Xanthomonas perforans, and the resident microflora are assessed in this study. The community dynamics assessed in this study include dysbiosis, type VI secretion system (T6SS) utilization and its influence on the phyllosphere microbiome, intraspecific diversity, and disease severity. With a combination of culture-dependent and culture-independent approaches, this study evaluated dysbiosis events between phyllosphere residents and X. perforans. This study suggests that the presence of T6SS creates a shift in the overall composition of the phyllosphere microbiome in the early colonization of the pathogen. Further evaluation of intraspecific diversity observed at the field-level across Alabama were implemented in greenhouse conditions to determine whether co-infection of multiple genotypes lead to higher disease severity. This study reveals that mixed infections of one or more genotypes of X. perforans leads to higher disease severity.