Light-activated fluorescent NO donor enables spatiotemporal tracking and stomatal closure in Arabidopsis thaliana.

We designed P1G3, a light-triggered NO donor from N-nitroso-naphthalene derivatives, releasing NO via N-NO cleavage while producing fluorescent P1G2 for real-time tracking. The quantity of NO released from P1G3 in the cytoplasm can be precisely regulated by light duration and light intensity, thereby minimizing the risk of unintended self-leakage in biological settings. Utilizing a quantitative mapping relationship between nitric oxide release and fluorescence intensity, we calculated for the first time the nitric oxide conversion rate of a donor system in a cellular environment. Both a method for nitric oxide quantification is proposed and the stable conversion efficiency of this donor is demonstrated. In Arabidopsis thaliana, P1G3 successfully induced Ca2+ accumulation in guard cells and triggered the gradual closure of stomata, demonstrating spatiotemporal-controlled NO delivery for enhanced drought tolerance.