A Short Note On Blue Light Receptors The Synthesis Of...

Cryptochromes are flavoprotein blue light receptors found throughout the biological Kingdom with many important signaling roles. Recently, it has been shown that cryptochromes catalyse the synthesis of reactive oxygen species (ROS) in the course of flavin reoxidation after blue light exposure. Although ROS are themselves important cellular regulators, it has remained unclear whether biosynthesis of ROS contributes to cryptochrome signaling. Here we show by fluorescence imaging techniques that ROS accumulates in the plant nucleus within minutes after cryptochrome activation by blue light, resulting in the activation of ROS regulated genes. Mutant alleles of cryptochrome that retain the capacity to synthesize ROS are active in redox regulation even though they have lost the ability to regulate photomorphogenesis. We conclude that ROS formation by cryptochrome has a cellular signaling role that is distinct from the known mechanisms of light induced conformational change regulating growt h and development. These results suggest novel optogenetic tools to induce ROS through targeted illumination of cryptochrome. Introduction Cryptochromes are blue light sensing receptors that regulate many aspects of plant growth and development, including de-etiolation, photomorphogenesis, the initiation of flowering, stress response, and hormone signaling (ref). They play a particularly large role in nuclear transcript regulation, with almost 10% of plant genes directly or indirectly under