Characterizing Rhizobial Diversity in Legumes from Pine Rockland Soils in South Florida

Pine rocklands are globally endangered ecosystems unique to South Florida, the Bahamas and Cuba. Due to karstic calcium carbonate-rich soil, these systems are limited in phosphorus and nitrogen, making symbiotic soil mutualisms critical to plant success. Pine rocklands contain the highest plant diversity of any other habitat in Florida, with over 400 native plants, a large number of which are endangered. These habitats are highly threatened by development and sea level rise. Legume-rhizobium interactions studies have not been previously conducted in pine rocklands, and the diversity of rhizobia across the remaining forest patches is unknown. Four leguminous species representing a range of crops, native species, and exotic species (Cajanus cajan-crop, Tephrosia purpurea- endangered, Chamaecrista fasciculata-native, and Abrus precatorius-invasive) will be use to trap rhizobia from four different pine rockland soils that will be either treated with saline water simulating sea level rise or distilled water. Planting initiated in late May, and harvesting of roots for nodules began in early July. DNA isolation and Illumina sequencing will follow immediately in order to identify rhizobial strains. It is expected to find differences in rhizobial communities based on their host plant, with crops and exotics utilizing a greater range of rhizobial strains, as well as an increase in the variation of rhizobia within each remaining forested area.