WRKY: its structure, evolutionary relationship, DNA-binding selectivity, role in stress tolerance and development of plants

The plants during their sessile, autotrophic lifestyle are affected by wide range of environmental signals and regulate complex patterns of gene expression with the help of transcription factors. The WRKY transcription factors are considered as plant-specific, however, are also reported in protist, slime mold, fern and pine. The WRKY name is coined from its highly conserved 60 amino acid long WRKY domain. These TFs show W box specific binding which is also influenced by the W box flanking sequence. During evolution, the family has expanded in different patterns to facilitate distinct cellular, developmental, and physiological role in plants. The WRKY TFs form one of the largest families in flowering plants, and play a broad spectrum regulatory role as positive and negative regulators of plant defense regulation, abiotic stresses and also involved in growth and development of plants.