The CRYPTOCHROME1-Dependent Response to Excess Light Is Mediated through the Transcriptional Activators ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 and ZML2 in Arabidopsis

Abstract

Exposure of plants to light intensities that exceed the electron utilization capacity of the chloroplast has a dramatic impact on nuclear gene expression. The photoreceptor Cryptochrome 1 (cry1) is essential to the induction of genes encoding photoprotective components in Arabidopsis thaliana. Bioinformatic analysis of the cry1 regulon revealed the putative ciselement CryR1 (GnTCKAG), and here we demonstrate an interaction between CryR1 and the zinc finger GATA-type transcription factors ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 (ZML1) and ZML2. The ZML proteins specifically bind to the CryR1 cis-element as demonstrated in vitro and in vivo, and TCTAG was shown to constitute the core sequence required for ZML2 binding. In addition, ZML2 activated transcription of the yellow fluorescent protein reporter gene driven by the CryR1 cis-element in Arabidopsis leaf protoplasts. T-DNA insertion lines for ZML2 and its homolog ZML1 demonstrated misregulation of several cry1-dependent genes in response to excess light. Furthermore, the zml1 and zml2 T-DNA insertion lines displayed a high irradiance-sensitive phenotype with significant photoinactivation of photosystem II (PSII), indicated by reduced maximum quantum efficiency of PSII, and severe photobleaching. Thus, we identified the ZML2 and ZML1 GATA transcription factors as two essential components of the cry1-mediated photoprotective response.

A MYB/ZML Complex Regulates Wound-Induced Lignin Genes in Maize

“…Upon MeJA treatment, R2R3-MYBs are released by the MeJA-induced degradation of the JAZ proteins, and the target genes are subsequently activated Song et al, 2011). Within the ZML subfamily, Arabidopsis ZML1 and ZML2 can bind DNA, suggesting that these proteins can act as transcriptional regulators (Shaikhali et al, 2012). How ZML factors cooperate with other regulators to activate or repress gene expression and to what extent protein degradation is part of the regulatory function of ZML factors remain unknown.…”

HSP90, ZTL, PRR5 and HY5 integrate circadian and plastid signaling pathways to regulate CBF and COR expression.

“…Protoplasts were isolated and transformed with ZTL-Myc or HY5-HA constructs and analyzed as described by Shaikhali et al (2012).…”

Characterization of Flowering-related Genes and Flowering Response in Relation to Blue Light in <i>Gypsophila paniculata</i>

“…This difference in the response to light quality between the ft mutant and the wild type in A. thaliana seems to have commonalities with the difference between 'Bristol Fairy' and 'Million Star' in G. paniculata. We analyzed the G. paniculata homologs of FKF1 (Hori et al, 2011). An E-box and TCTAG motif, which may be important in blue light-dependent FT expression (Liu et al, 2013;Shaikhali et al, 2012), were found in this region from MS.…”

“…7). The deleted region contained an E-box (CANNTG) and a TCTAG se- quence, which are reportedly associated with the response to blue light through the CRY pathway (Liu et al, 2013;Shaikhali et al, 2012).…”