The microbial communities, or microbiomes, associated with plant roots are key components of the health of every plant on Earth. This project will investigate the role of root microbiomes in the successful colonization and growth of the American beachgrass, Ammophila breviligulata. This plant is considered an important sand dune architect on barrier islands and other coastal environments in the mid-Atlantic and Northeast. Its ability to colonize and trap sand promotes the formation of sand dunes that offer protection to coastal ecosystems. However, severe storms can dramatically disturb dunes and eliminate the protection previously provided by these structures. While many efforts have been made to replant American beachgrass after storm overwash or events like Hurricane Sandy, they are not always successful. The main goal of this project is to elucidate the impact of root microbiomes on the health of the American beachgrass by studying the interactions between the plant and its root-associated microbes across multiple sites at varying degrees of plant health. The findings will be shared with local government and environmental offices with the goal of identifying strategies for implementation of improved microbiomes on current replanting activities as well as providing educational opportunities for the community in the form of brief workshops about sand dune ecosystems from the point of view of plant-microbe interactions. In addition, this project will train graduate, undergraduate and high school students at Hofstra University, a predominantly undergraduate institution, in field work, plant microbiology, and microbiome analysis techniques, providing summer research-intensive internships.
The project will use both culture-based and genomic approaches to characterize plant-microbiome interactions in the beachgrass Ammophila breviligulata. Microbiomes in three beachgrass systems (wild beachgrass, successful, and unsuccessful replantings) will be characterized using microbial community analyses and transcriptomics targeting the 16S rRNA and nifH genes on multiple sites along the South Shore of Long Island. Microbial isolates from the rhizosphere of healthy beachgrass plants will be characterized and screened for the production of plant hormones such as indole-3-acetic acid (IAA) and other beneficial metabolites. Selected promising isolates from this screen will be studied in detail at the genomic and metabolomic level, and will serve as candidates for cocultivation with beachgrass in both growth media and greenhouse studies, as individual bioinoculants, and as reconstructed microbiomes. Greenhouse studies will encompass not only individual strains and "designed microbiomes", but also rhizosphere soil transplants from healthy plants to understand the role of the microbiome at increasing levels of complexity. Expanding our understanding of the plant-microbe interactions in Ammophila breviligulata has the potential to be applied to agricultural model plants that face similar challenges, including low nutrients, high salinity, high solar radiation and constant physical stress.
