WRKY Transcription Factor: Role in Abiotic and Biotic Stress

One of the fundamental behaviors of plants, being sessile allows them to develop an intricate molecular machinery to adapt themselves to biotic and abiotic challenges experienced in the environment. In response to adapt against a particular stress, a massive transcriptional activity of several genes triggered the defense responses in the plant cell. Extensive research on stress related studies have introduced the role of transcription factors for regulation of the plants responses. In many cases, transcription factors acts as a “master or key regulator” of gene expression under one or multiple stress conditions. In plants, WRKY has emerged as a major and largest transcription factor family. Arabidopsis and rice has 74 and 109 WRKY members respectively, which play a major role during stress and development. WRKY gene family has been studied to be induced in response to several phytohormones such as SA, JA, ABA and pathogen attack, thus have been found to be a key player in plant defense mechanism. This gene family also forms a highly interacting regulatory network with stress response, by acting as either transcription activator or repressor thereby modulating the gene expression. Beside stress and developmental conditions, WRKY is also induced in nutrient deficient conditions such as phosphate deficiency and starvation. The main emphasis of this review is to summarize the progress in WRKY transcription factor research under stress and developmental conditions. At the same time an attempt has also been made to comment upon interaction with a wide range of signaling networks such as MAP kinase proteins, 14-3-3 proteins, calmodulin and regulator of chromatin such as histone deacetylases, and plant-pathogen defense proteins. Moreover, a crosstalk or overlap is also discussed among these different components or pathways involving WRKY transcription factor. _____________________________________________________________________________________________________________