A basic helix-loop-helix transcription factor in Arabidopsis, MYC2, acts as a repressor of blue light-mediated photomorphogenic growth
Yadav, V.; Mallappa, C.; Gangappa, S.N.; Bhatia, S.; Chattopadhyay, S.
Plant Cell 17(7): 1953-1966
ISSN/ISBN: 1040-4651 PMID: 15923349 DOI: 10.1105/tpc.105.032060
The crosstalk of light signaling pathways with other signaling cascades has just started to be revealed. Here, we report the identification and functional characterization of a Z-box binding factor (ZBF1) in light signaling pathways. Arabidopsis thaliana ZBF1 encodes AtMYC2/JIN1, a basic helix-loop-helix transcription factor, which has recently been shown to be involved in abscisic acid (ABA), jasmonic acid (JA), and jasmonate-ethylene signaling pathways. We demonstrate that AtMYC2 interacts with the Z- and G-box light-responsive elements of minimal light-regulated promoters. AtMYC2 is expressed in various light-grown seedlings, including in red, far red, and blue light. Genetic analyses suggest that AtMYC2 acts as a negative regulator of blue light-mediated photomorphogenic growth and blue and far-red-light-regulated gene expression; however, it functions as a positive regulator of lateral root formation. Our results further demonstrate that atmyc2 mutants have compromised sensitivity to ABA- and JA-mediated responses. Taken together, these results demonstrate that AtMYC2 is a common transcription factor of light, ABA, and JA signaling pathways in Arabidopsis.