Carpenteria Salt Marsh Phyllosphere Bacterial Communities June 2014

Although rhizosphere microbial communities of plants growing in salt marshes have been investigated to some extent, leaf surface communities of these plants have not received as much attention. We have used high throughput sequencing of 16S rRNA gene amplicons to characterize the phyllosphere bacterial communities of five coastal salt marsh plants that vary in their adaptations to a high salt environment - the succulents Salicornia virginica and Arthrocnemum subterminale, the salt-excreters Limonium californicum and Frankenia salina, and Atriplex lentiformis, a plant with salt-storing trichomes. The most distinct bacterial communities were found on Salicornia leaves. These were dominated by Bacteroidetes and Alphaproteobacteria whereas the other plants had much greater numbers of Gammaproteobacteria, especially the genera Halomonas and Kushneria. Leaf washes of the five plants were analyzed for a variety of inorganic ions, including sodium, potassium and chloride. Not surprisingly, the two salt-excreters had the highest amounts of salt on their leaf surfaces, but the connection to bacterial community composition remains to be determined.