Terrestrial plants have diverse and sophisticated mechanisms for defending against predation and pathogens, but the defenses of photosynthetic microbes in aquatic ecosystems are much less well understood. Synechococcus are aquatic/marine cyanobacteria that substantially contribute to global primary productivity. This project will employ two main approaches to study Synechococcus defenses against protist predators. Experiments will examine the mechanism(s) by which cell surface proteins provide a constitutive (continuously expressed) defense and assay the generality of this defense among Synechococcus strains and against diverse predator types. Secondly, co-culture techniques, in which Synechococcus are grown in the presence of predators, will be used to characterize protein-based induced defenses that may arise in response to predation. The formation of aggregates as a possible induced defense by Synechococcus will also be examined in field and laboratory settings. Aggregate formation is important for the biogeochemistry and ecological functioning of planktonic communities since aggregates can be the site of unique biogeochemical processes. The research is cross-cutting on a number of levels: it examines constitutive and induced defenses in both controlled laboratory and natural settings; it leverages the suite of available Synechococcus genomes to enable a mechanistic investigation of microbial defense processes; and it represents a synthesis of ecological and genomic approaches to the study of microbial interactions that are fundamental to biogeochemical cycling and the maintenance of biodiversity in aquatic ecosystems.
Broader impacts of this project include support of graduate and undergraduate students, including ethnic minority participants in Shannon Point Marine Center's Multicultural Initiatives in Marine Science Undergraduate Program (MIMSUP). Other impacts include development of instructional modules for elementary and high school students, and maintenance and distribution of culture collections.
