Nuclear factor Y-A3b binds to the promoter and regulates flowering time in tomato.

The control of flowering time is essential for reproductive success and has a major effect on seed and fruit yield and other important agricultural traits in crops. Nuclear factors Y (NF-Ys) are transcription factors that form heterotrimeric protein complexes to regulate gene expression required for diverse biological processes, including flowering time control in plants. However, to our knowledge, there has been no report on mutants of individual NF-YA subunits that promote early flowering phenotype in plants. In this study, we identified , encoding a member of the NF-Y transcription factor family, as a key gene regulating flowering time in tomato. Knockout of resulted in an early flowering phenotype in tomato, whereas overexpression of delayed flowering in transgenic tomato plants. NF-YA3b was demonstrated to form heterotrimeric protein complexes with multiple NF-YB/NF-YC heterodimers in yeast three-hybrid assays. Biochemical evidence indicated that NF-YA3b directly binds to the CCAAT -elements of the () promoter to suppress its gene expression. These findings uncovered a critical role of in regulating flowering time in tomato and could be applied to the management of flowering time in crops.