IDENTIFICATION AND CHARACTERIZATION OF FLOWER LOCUS T INTERACTING PROTEIN 7 IN ARABIDOPSIS

Abstract

In Arabidopsis, several flowering genetic pathways are converged at floral pathway integrators, such as FT and SOC1. FT is expressed in the vasculature and its protein moves from leaves to the shoot apex to induce flowering, which is precisely modulated by an ER membrane protein, FT INTERACTING PROTEIN 1 (FTIP1). Here we show that FTIP7, a close homolog of FTIP1, also plays a role in regulating flowering time. ftip7-1 mutants significantly enhance the late flowering phenotype of ftip1-1 under long days, but not under short days. During the floral transition, FTIP7 expression gradually increases in the shoot apex, which coincides with FT loading into the shoot apical meristem (SAM). Like FTIP1, FTIP7 interacts with FT as revealed by yeast two-hybrid assays. FT protein distribution in the SAM is affected in ftip7-1, suggesting a role of FTIP7 in mediating FT unloading from vasculatures into the SAM. Taken together, our results suggest that FTIP7 promotes flowering through affecting FT transport during the floral transition in Arabidopsis.