Graduate Student University of Washington Seattle, Washington
Body of Abstract: Seagrasses are marine angiosperms that serve as a key component of marine coastal ecosystems and contribute to essential habitat of intertidal organisms. Eelgrass (Zostera marina), the most wide-ranging seagrass, is an essential foundation species and is threatened by natural and anthropogenic pressures related to climate change. Eelgrass has two methods of propagation: clonal branching and sexual reproduction via seasonal flowering. Flowering and seed production in eelgrass is considered important for persistence and resilience and contributes broadly to genetic diversity among populations. However, the molecular mechanism of flowering in eelgrass as well as the environmental factors contributing to flowering are so far unknown. This project seeks to improve our understanding of flowering (sexual reproduction) in eelgrass and investigate the influence of environmental factors on flowering time and frequency in populations. We have identified four candidate florigen genes (FLOWERING LOCUS T homologs) in Z. marina that affect the timing of flowering when over-expressed in Arabidopsis thaliana. Our results suggest that two candidates are activators of flowering, while the other two are repressors. Using qPCR data, we observed higher expression levels of both repressive FT-like genes (anti-florigen) in vegetative Z. marina tissues collected from three populations in Willapa Bay, WA. These results have led us to hypothesize that the expression level of the repressive FT-like genes is a major determinant of flowering time in Z. marina, although the levels of both activators also contribute to flowering time. We propose the presence of the anti-florigen maintains the vegetative state in shoots, and when it is substantially reduced, the shoot experiences the onset of flowering. Improving our understanding of flowering in eelgrass will give insights into how populations will respond to climate change and help inform restoration efforts and eelgrass management practices.