An isolated nucleic acid construct including a nucleic acid molecule encoding a light-labile, phytochrome A, a light-inducible promoter which is 5' to the nucleic acid molecule encoding a light-labile, phytochrome A, and a terminator region which is 3' to the nucleic acid molecule encoding a light-labile, phytochrome A is disclosed. Methods for regulating a plant's canopy architecture and regulating a plant's seed yield, which involve transgenic plants or transgenic plant seeds including an isolated nucleic acid construct according to the present invention, are also disclosed.