AP2/EREBP transcription factors are part of gene regulatory networks and integrate metabolic, hormonal and environmental signals in stress acclimation and retrograde signalling

Abstract

To optimize acclimation responses to environmental growth conditions, plants integrate and weigh a diversity of input signals. Signal integration within the signalling networks occurs at different sites including the level of transcription factor activation. Accumulating evidence assigns a major and diversified role in environmental signal integration to the family of APETALA 2/ethylene response element binding protein (AP2/EREBP) transcription factors. Presently, the Plant Transcription Factor Database 3.0 assigns 147 gene loci to this family in Arabidopsis thaliana, 200 in Populus trichocarpa and 163 in Oryza sativa subsp. japonica as compared to 13 to 14 in unicellular algae ( http://plntfdb.bio.uni-potsdam.de/v3.0/ ). AP2/EREBP transcription factors have been implicated in hormone, sugar and redox signalling in context of abiotic stresses such as cold and drought. This review exemplarily addresses present-day knowledge of selected AP2/EREBP with focus on a function in stress signal integration and retrograde signalling and defines AP2/EREBP-linked gene networks from transcriptional profiling-based graphical Gaussian models. The latter approach suggests highly interlinked functions of AP2/EREBPs in retrograde and stress signalling.

Fast Retrograde Signaling in Response to High Light Involves Metabolite Export, MITOGEN-ACTIVATED PROTEIN KINASE6, and AP2/ERF Transcription Factors in Arabidopsis

“…AP2/ERF-TFs are known to be involved in abiotic stress response (Agarwal et al, 2006;Dietz et al, 2010) and light acclimation (Koussevitzky et al, 2007;Khandelwal et al, 2008;Gordon et al, 2012). The identified AP2/ERF-TF coexpression network of 19 members revealed H-light responsiveness (Figure 1), 12 members of which were upregulated at t = 10 min following the L→H shift and upon N→H shift.…”

“…We analyzed the transcriptional responses to high (H) light of members of a potential AP2/ERF-TF coexpression network (Dietz et al, 2010) using plants that were fully acclimated to L-light, as previously shown based on chloroplast ultrastructure and electron transport rate (Oelze et al, 2012). Upon transfer to H-light, transcript levels of antioxidant defense and marker genes of retrograde signaling profoundly changed in these plants within 6 h (Oelze et al, 2012;Alsharafa et al, 2014).…”

“…The network was constructed as previously published (Dietz et al, 2010). Moreover, a second database (Expression Angler; Toufighi et al, 2005) was employed to resolve the coexpression network in more detail.…”

“…Besides their role in developmental processes like flower organ development (Jofuku et al, 1994), they strongly respond to various abiotic stressors and are involved in stress acclimation (Dietz et al, 2010;Lata and Prasad, 2011). Involved in responses to cold, salinity, or drought stress, DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN1A (DREB1A), 2A, 1B, and 2B probably are the best studied representatives of stressresponsive AP2/ERF-TFs (Sakuma et al, 2006).…”

The Potential of Transcription Factor-Based Genetic Engineering in Improving Crop Tolerance to Drought

“…In the Arabidopsis genome, the AP2/ERF family comprises 9% of the total 1600 TFs annotated (Feng et al, 2005;PerezRodriguez et al, 2010;Riano-Pachon et al, 2007). The AP2/ ERF TFs are a group of plant-specific TFs involved in regulating diverse developmental and regulatory processes (Dietz et al, 2010). The AP2/ERF family is composed of four to five subfamilies: the AP2, RAV, ERF, the dehydrationresponsive element binding protein (DREB), and others (AL079349) .…”