Spatial Variation of Bacterial Communities on the Leaves of Southern Magnolia Trees

Bacteria are found in almost all environments on earth, including on the surface of other living things. Bacteria that exist on the leaves of plants (the phyllosphere) are of interest because of the potentially harsh nature of the environment they inhabit, and of applied interest. Although there has been a substantial amount of research in phyllosphere microbiology, few studies have examined the effect of spatial variation on phyllosphere community composition. This project investigated the effect of spatial variation on the bacterial communities living on the surface of Magnolia grandiflora leaves. Following DNA extraction, next generation sequencing of 16S rRNA gene fragments was used to determine the structure of the bacterial phyllosphere community on individual leaves, focusing comparisons on different leaves from the same tree and on leaves from trees at different distances apart. NMDS ordination was used to depict the degree of similarity between leaf samples. The dominant phyla and subphyla found on the leaf surfaces generally included those of a typical phyllosphere community and with few exceptions, leaves from the same tree tended to have similar bacterial communities. Spatial variation was shown to have some influence on the phyllosphere community, but there was no obvious relationship between distance between trees and community similarity, suggesting that other spatial factors (environmental variation, specific location) are also important