Title : Functional Interconnection of MYC2 and SPA1 in the Photomorphogenic Seedling Development of Arabidopsis.
MYC2 is a bHLH transcription factor that cross-talks with light, ABA (abscisic acid) and JA (jasmonic acid) signaling pathways. Here, we have shown that MYC2 directly binds to the G-box present in SPA1 promoter, and it controls the expression of SPA1 in a COP1 dependent manner. Analyses of atmyc2 spa1 double mutants suggest that whereas MYC2 and SPA1 act redundantly to suppress photomorphogenic growth in the dark, they function synergistically for the suppression of photomorphogenic growth in light. Our studies have also revealed that MYC2-mediated ABA and JA responses are further modulated by SPA1. Taken together, this study demonstrates the molecular and physiological interrelations of MYC2 and SPA1 in light, ABA and JA signaling pathways.