Ro KSN, a floral repressor, forms protein complexes with Ro FD and Ro FT to regulate vegetative and reproductive development in rose

Abstract

Summary: FT/TFL 1 family members have been known to be involved in the development and flowering in plants. In rose, R o KSN, a TFL 1 homologue, is a key regulator of flowering, whose absence causes continuous flowering. Our objectives are to functionally validate R o KSN and to explore its mode of action in rose. We complemented A rabidopsis tfl1 mutants and ectopically expressed R o KSN in a continuous‐flowering (CF) rose. Using different protein interaction techniques, we studied R o KSN interactions with R o FD and R o FT and possible competition. In Arabidopsis, R o KSN complemented the tfl1 mutant by rescuing late flowering and indeterminate growth. In CF roses, the ectopic expression of R o KSN led to the absence of flowering. Different branching patterns were observed and some transgenic plants had an increased number of leaflets per leaf. In these transgenic roses, floral activator transcripts decreased. Furthermore, R o KSN was able to interact both with R o FD and the floral activator, R o FT. Protein interaction experiments revealed that R o KSN and R o FT could compete with R o FD for repression and activation of blooming, respectively. We conclude that R o KSN is a floral repressor and is also involved in the vegetative development of rose. R o KSN forms a complex with R o FD and could compete with R o FT for repression of flowering.