AUTHOR=Shan Xiaozhen , Yang Yun , Wei Shuoqi , Wang Chao , Shen Weishi , Chen Hou-bin , Shen Ji-yuan 

TITLE=Involvement of CBF in the fine-tuning of litchi flowering time and cold and drought stresses

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1167458

DOI=10.3389/fpls.2023.1167458

ISSN=1664-462X

ABSTRACT=<p>Litchi (<italic>Litchi chinensis</italic>) is an economically important fruit tree in southern China and is widely cultivated in subtropical regions. However, irregular flowering attributed to inadequate floral induction leads to a seriously fluctuating bearing. Litchi floral initiation is largely determined by cold temperatures, whereas the underlying molecular mechanisms have yet to be identified. In this study, we identified four <italic>CRT/DRE BINDING FACTORS</italic> (<italic>CBF</italic>) homologs in litchi, of which <italic>LcCBF1</italic>, <italic>LcCBF2</italic> and <italic>LcCBF3</italic> showed a decrease in response to the floral inductive cold. A similar expression pattern was observed for the <italic>MOTHER OF FT AND TFL1</italic> homolog (<italic>LcMFT</italic>) in litchi. Furthermore, both LcCBF2 and LcCBF3 were found to bind to the promoter of <italic>LcMFT</italic> to activate its expression, as indicated by the analysis of yeast-one-hybrid (Y1H), electrophoretic mobility shift assays (EMSA), and dual luciferase complementation assays. Ectopic overexpression of <italic>LcCBF2</italic> and <italic>LcCBF3</italic> in <italic>Arabidopsis</italic> caused delayed flowering and increased freezing and drought tolerance, whereas overexpression of <italic>LcMFT</italic> in <italic>Arabidopsis</italic> had no significant effect on flowering time. Taken together, we identified LcCBF2 and LcCBF3 as upstream activators of <italic>LcMFT</italic> and proposed the contribution of the cold-responsive CBF to the fine-tuning of flowering time.</p>