Florigen and antiflorigen gene expression correlates with reproductive state in a marine angiosperm, Zostera marina

·       Florigen and antiflorigen genes within the phosphatidylethanolamine-binding protein (PEBP) family regulate flowering in angiosperms. In eelgrass (Zostera marina), a marine foundation species threatened by climate change, flowering and seed production are crucial for population resilience. Yet, the molecular mechanism underpinning flowering remains unknown. ·       Using phylogenetic analysis and functional assays in Arabidopsis, we identified thirteen PEBP genes in Z. marina (ZmaPEBP) and showed that four genes altered flowering phenotypes when overexpressed. We used quantitative RT-PCR on Z. marina shoots from perennial and annual populations in Willapa Bay, USA to assess expression of these four genes in different tissue and expression changes throughout the growth season. ·       We demonstrated that ZmaFT2 and ZmaFT4 promote flowering, and ZmaFT9 and ZmaTFL1a repress flowering in Arabidopsis. Across four genetically-assessed sites with eelgrass, ZmaFT2 and ZmaFT4 were expressed in leaves of both vegetative and reproductive shoots but only induced in rhizomes of reproductive shoots.  ZmaFT9 was distinctively expressed in leaves of vegetative and juvenile shoots, while ZmaTFL1a levels increased after flowering shoots had developed. ·       Our results suggest that ZmaFT2 and ZmaFT4 may promote flowering, while ZmaFT9 may inhibit a floral transition in eelgrass. We speculate that ZmaTFL1a may be involved in flowering shoot architecture.

Impact/Purpose

Eelgrass (Zostera marina) is essentially an underwater city, like Atlantis, that provides many important benefits to estuarine ecosystems such as sediment stabilization, nutrient removal, carbon sequestration and essential fish habitat.  Flowering and seed production play a key role in contributing to persistence and increasing genetic diversity within local eelgrass populations.  Identifying genetic markers of flowering would provide a method for predicting seed potential within a population and such advances could ultimately allow for more strategic and efficient seed-based restoration efforts of eelgrass. We confirmed thirteen eelgrass florigen genes (ZmaPEBP) and demonstrated that four are likely functionally relevant to the flowering pathway, both as activators and repressors. The function of these genes has not previously been investigated in marine flowering plants like eelgrass.

Citation

Nolan, C., I. Campbell, A. Farrell-Sherman, B. Briones Ortiz, C. Yang, K. Naish, V. Di Stilio, Jim Kaldy, C. Donoghue, J. Ruesink, AND T. Imaizumi. Florigen and antiflorigen gene expression correlates with reproductive state in a marine angiosperm, Zostera marina. Elsevier B.V., Amsterdam, NETHERLANDS, 28(8):113082, (2025). [DOI: 10.1016/j.isci.2025.113082]

DOI: Florigen and antiflorigen gene expression correlates with reproductive state in a marine angiosperm, Zostera marina