WRKY transcription factors: evolution, binding, and action

Abstract

The WRKY transcription factor (TF) gene family expanded greatly in the evolutionary process from green algae to flowering plants through whole genome, segmental, and tandem duplications. Genomic sequences from diverse plant species provide valuable information about the origin and evolution of WRKY domain-containing proteins. Accumulating data indicate that WRKY TFs bind W-box and/or other cis-elements, revealing the specificity of ciselement recognition based on the structure of the WRKY protein as well as the nucleotides adjacent to the core sequences. Physical interactions among WRKY proteins or between WRKY proteins and other regulatory factors afford important insights into the regulation of this TF family. WRKY proteins are essential players in the kinase signaling network. The interaction of plant resistance (R) proteins with WRKY TFs and the existence of unusual chimeric R-WRKY proteins suggest diversity in signaling pathways for rapid immune responses. In this review, we focus mainly on progress in understanding the function of WRKY TFs in response to biotic stresses and focus on their multiple roles in Arabidopsis and rice plants.

Genome-wide identification and expression analysis of WRKY transcription factors in pearl millet (Pennisetum glaucum) under dehydration and salinity stress

“…For example, PgWRKY3 (a Group IV member) has two WRKY domains with no zinc-finger motif at N-terminal that clustered with Group I members. It clearly suggests that it may be evolved from Group I WRKY family of P. glaucum [39,40]. The phylogenetic tree analysis, based on sequence similarity with functionally characterized WRKYs of A. thaliana, O. sativa and S. italica allowed for predicting and conferring the possible involvement of PgWRKYs in stress responsive processes.…”

WRKY1 Mediates Transcriptional Regulation of Light and Nitrogen Signaling Pathways

“…Thus, it is important to consider whether WRKY1 is involved in shared or unique responses to N and/or light signaling. Evidence from the literature suggests that WRKY TFs help fine-tune plant response to specific stresses (Chen et al, 2019). For example, mitogen-activated protein kinase (MAPK) cascades are activated early following the perception of stress stimuli, and many WRKY family TFs have been identified as substrates for MAPKs.…”

“…For example, mitogen-activated protein kinase (MAPK) cascades are activated early following the perception of stress stimuli, and many WRKY family TFs have been identified as substrates for MAPKs. MAPKs phosphorylate different WRKY proteins to either positively or negatively modulate their DNA-binding ability (Chi et al, 2013;Chen et al, 2019). AtWRKY33 is phosphorylated by AtMPK3/AtMPK6 in response to Botrytis cinerea infection, which specifically influences pathogen-induced camalexin accumulation (Mao et al, 2011).…”

“…WRKY family TFs are known to have PPI with chromatin remodeling, calmodulin, and 14-3-3 proteins (Chi et al, 2013;Chen et al, 2019), which could result in "indirect" transcriptional regulation in response to light and/or N signals in the WRKY1 mutants. Interestingly, one of the most significant CREs found in the promoters of the up-regulated genes in the WRKY mutants was the G-box, and the only confirmed protein-protein interaction for AtWRKY1 is with a 14-3-3 protein, GRF1.…”

Genome-wide identification and expression analysis of WRKY transcription factors in pearl millet (Pennisetum glaucum) under dehydration and salinity stress.

“…For example, PgWRKY3 (a Group IV member) has two WRKY domains with no zinc-finger motif at N-terminal that clustered with Group I members. It clearly suggests that it may be evolved from Group I WRKY family of P. glaucum [38,39] sativa and S. italica, which indicates that these orthologous pairs may already exist before the ancestral divergence [42]. The functional information of PgWRKYs can be predicted according to their identified orthologous WRKYs in Arabidopsis, Rice and Foxtail millet.…”