The PFT1 (Phytochrome and Flowering Time 1) locus is described and identified. PFT1 acts in a light-quality pathway downstream of phyB that acts through modulation of FT transcription. Plants containing a truncated pft1 gene display an altered shade avoidance syndrome including an increase in time to flowering. The corresponding PFT1 gene has been isolated and characterized. Recombinant vectors, recombinant plants containing the PFT1 gene and methods of using the PFT1 gene to modulate a photosensitive trait, especially time to flowering, are described.