A look into the diversity of culturable bacterial root endophytes in Batis maritima

Plants are known to associate and interact with diverse microbes, including those that colonize and live within their root tissues (endophytes), that perform key functional roles for the plants, such as salinity and drought tolerance. A variety of biotic (e.g., plant host abundance) and abiotic factors (e.g., soil pH) can influence to a varying degree, the rates and patterns of endophyte colonization on roots of plants; however, current knowledge is still limited, especially for coastal marsh plants. We investigated the relative influences of biotic and abiotic factors that shape the fine-scale diversity patterns of bacterial root endophyte colonization communities associated with the coastal marsh succulent plant Batis maritima (saltwort) using a culture-based approach. We set up five experimental blocks, each containing four plots: 90% B. maritima, 50% B. maritima with woody plants, i.e., mangrove, 50% B. maritima without woody plants, and 10% B. maritima dominated. For each plot, we collected three plant samples and measured environmental factors such as pH, salinity, and light availability. For each sample, we cultured bacterial endophytes, then extracted, amplified, and sequenced their DNA for identification. We expect that salinity and host plant abundance will influence the diversity of bacterial root endophyte communities. Additionally, the presence of woody plants and plant communities with a higher diversity will harbor a high endophytic diversity. In contrast to our expectations, our preliminary results indicate that the plots without woody plants yield the highest number of culturable bacterial growth (72.67%). Plots with low B. maritima abundance (10%) has the smallest number of growing bacterial cultures (53.33%). Our project gives insight into what host plant diversity, abundance, and local environmental processes influence plant-microbe colonization and distribution in coastal marshes.