AbstractsBiology & Animal Science

Plants respond to different qualities and quantities of light through photoreceptors, which lead to a cascade of genes being turned on and off. Phytochrome A is a photoreceptor that is active in plant development from seed germination to flowering and triggers the phytochrome A pathway. The SPA1 protein is specific to the phytochrome A pathway and is a negative regulator of phyA. By exposing plants to various light treatments, we found spa1 plants have enhanced positive phototropic responses of roots to red light. We also report that red and green light pulses interrupt phototropic responses of hypocotyls to blue light via SPA1. From these findings, we conclude that PHYA is responsible for positive phototropic responses of roots, and that the SPA1 protein is a key protein in crosstalk between photoreceptor pathways.