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The Nuclear Factor Y subunits NF-YB2 and NF-YB3 play additive roles in the promotion of flowering by inductive long-day photoperiods in Arabidopsis
- Kumimoto, Roderick W., Adam, Luc, Hymus, Graham J., Repetti, Peter P., Reuber, T. Lynne, Marion, Colleen M., Hempel, Frederick D., Ratcliffe, Oliver J.
- Planta 2008 v.228 no.5 pp. 709-723
- Arabidopsis, DNA, flowering, gene expression regulation, loci, models, play activities, proteins, yeasts
- Accumulating evidence supports a role for members of the plant Nuclear Factor Y (NF-Y) family of CCAAT-box binding transcription factors in the regulation of flowering time. In this study we have used a genetic approach to show that the homologous proteins NF-YB3 and NF-YB2 have comparable activities and play additive roles in the promotion of flowering, specifically under inductive photoperiodic conditions. We demonstrate that NF-YB2 and NF-YB3 are both essential for the normal induction of flowering by long-days and act through regulation of the expression of FLOWERING LOCUS T (FT). Using an ELISA-based in-vitro assay, we provide a novel demonstration that plant NF-YB subunits are capable of directly binding to a CCAAT-box containing region of the FLOWERING LOCUS T promoter as part of an NF-Y trimer in combination with the yeast HAP2 and HAP5 subunits. These results support an emerging model in which NF-Y complexes provide a component of the DNA target specificity for transcriptional regulators such as CONSTANS.