Non-vernalization requirement for flowering in Brassica rapa conferred by a dominant allele of FLOWERING LOCUS T

Abstract Controlling the timing of flowering is key to improving yield and quality of several agricultural crops including the Brassicas. Many Brassicaceae plants possess a conserved flowering mechanism in which FLOWERING LOCUS C (FLC) represses the transcription of flowering activators, such as FLOWERING LOCUS T (FT), during vernalization. Here, we employed genetic analysis based on next-generation sequencing to identify a dominate FT allele, BrFT2-C, for flowering in the absence of vernalization in the Brassica rapa cultivar ‘CHOY SUM EX CHINA 3’. BrFT2-C harbors two large insertions upstream of its coding region and is constitutively expressed without vernalization, despite FLCexpression. We show that BrFT2-C offers an opportunity to introduce flowering without vernalization requirement into winter-type brassica crops, including B. napus, which have many functional FLC paralogs. Furthermore, we demonstrated the feasibility of using B. rapa harboring BrFT2-C as rootstock for grafting to induce flowering in radish (Raphanus sativus), which requires vernalization for flowering. We believe that the ability of BrFT2-C to overcome repression by FLCcan have significant applications in brassica crops breeding to increase yields by accelerating or delaying flowering.