Phytochrome B and CIPK31 coordinate VOZ2-dependent gibberellic acid signaling in rice

Light and calcium signaling regulate gibberellic acid (GA) signaling in plants; however, how these signals are coordinated remains unknown. Here, we identified that phyB mutants exhibit dramatic semi-dwarfism, and transcriptome data showed that PhyB affects GA signaling genes involved in biosynthetic, catabolism and signaling transduction. We identified VOZ2, a transcription factor, as a PhyB-interacting protein involved in GA-related regulation. Similar to phyB , voz2 mutants also exhibited semi-dwarfism. Comparative transcriptome analysis showed that 62.9% of differentially expressed genes were coregulated by PhyB and VOZ2, suggesting a functional connection. CIPK31, a PhyB-interacting calcium-responsive protein kinase, also interacts with VOZ2 and may modulate its transcriptional activity. In addition, PhyB and CIPK31 competitively interact with VOZ2, implying a complex regulatory module. Our previous work showed that CIPK31 interacts with and stabilizes SLR1, a negative regulator of GA signaling, which also interacts with VOZ2. SLR1 interacts with and affect VOZ2 transcription activation activity. Further analyses suggested that VOZ2 regulates the expression of GA signaling genes, including the biosynthetic genes GA20ox3 , GA3ox1 , and GA3ox2 , and directly activates a subset of these targets while repressing GA catabolic genes. Together, these findings support a model in which VOZ2 acts as a regulator of GA-related genes, and a PhyB-CIPK31-VOZ2 module integrates light and calcium signals to modulate GA-associated processes in rice.