WRKY transcription factors: Jack of many trades in plants

Abstract

WRKY transcription factors are one of the largest families of transcriptional regulators found exclusively in plants. They have diverse biological functions in plant disease resistance, abiotic stress responses, nutrient deprivation, senescence, seed and trichome development, embryogenesis, as well as additional developmental and hormone-controlled processes. WRKYs can act as transcriptional activators or repressors, in various homo- and heterodimer combinations. Here we review recent progress on the function of WRKY transcription factors in Arabidopsis and other plant species such as rice, potato, and parsley, with a special focus on abiotic, developmental, and hormone-regulated processes.

Keywords: ROS homeostasis; WRKY; abiotic stress; biotic stress; phytohormones; seed development; senescence.

Figure 1. The consensus WRKY domain for each WRKY group in higher plants. The WRKY motif, the cysteines, and histidines that form the zinc finger are shown in boxes. The 4 β-strands are shown with arrows. I CT and I NT denote the N-terminal and C-terminal WRKY domains from group I WRKY proteins.

Figure 2A. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.

Figure 2B. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.

Figure 2C. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.

Figure 2D. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.

Figure 2E. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.

Figure 2F. The role of WRKYs and their genes in abiotic stress (A), biotic stress (B), the cross-talk between biotic and abiotic stress (C), metabolism (D), hormone signaling (E), and epigenetic control (F). The gray square boxes with the number refer to the individual WRKY proteins. WRKY genes are in green. The crosses demonstrate inhibiton of expression. A P in a yellow star refers to phosphorylation. Ub, ubiquitin.