Their C-termini divide Brassica rapa FT-like proteins into FD-interacting and FD-independent proteins that have different effects on the floral transition

• Published in: Frontiers in plant science Vol. 13; p. 1091563
• Main Authors: Lee, Areum, Jung, Haemyeong, Park, Hyun Ji, Jo, Seung Hee, Jung, Min, Kim, Youn-Sung, Cho, Hye Sun
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 12.01.2023
• Subjects: Chinese cabbage; floral meristem identity genes; flowering locus t (FT); flowering time; FT–FD interaction; Plant Science; flowering locus t (FT); floral meristem identity genes; flowering time; Chinese cabbage; FT–FD interaction
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2022.1091563

Members of the FLOWERING LOCUS T (FT)-like clade of phosphatidylethanolamine-binding proteins (PEBPs) induce flowering by associating with the basic leucine zipper (bZIP) transcription factor FD and forming regulatory complexes in angiosperm species. However, the molecular mechanism of the FT-FD heterocomplex in Chinese cabbage ( ssp. ) is unknown. In this study, we identified 12 genes and focused our functional analysis on four genes by overexpressing them individually in an loss-of-function mutant in . We determined that and promote flowering by upregulating the expression of floral meristem identity genes, whereas and , although close in sequence to their Arabidopsis counterparts, had no clear effect on flowering in either long- or short-day photoperiods. We also simultaneously genetically inactivated and in Chinese cabbage using CRISPR/Cas9-mediated genome editing, which revealed that and may play key roles in inflorescence organogenesis as well as in the transition to flowering. We show that BrFT-like proteins, except for BrTSF, are functionally divided into FD interactors and non-interactors based on the presence of three specific amino acids in their C termini, as evidenced by the observed interconversion when these amino acids are mutated. Overall, this study reveals that although homologs are conserved, they may have evolved to exert functionally diverse functions in flowering their potential to be associated with FD or independently from FD in .