"Review of literaturedevelopmental stage was reported by Miao et al., 2004. Rinerson et al., (2015b) hasproposed that out of 240 WRKY genes studied in switchgrass genome, 23 these genesshowed elevated mRNA levels during the onset of flag leaf senescence. Abscisic acid mediated signaling ABA functions through complex signaling networks, many parts of thesepathways include E3 ligases, Kinases, phosphatases, phospholipases, G proteins,receptor-like kinases and TFs (Umezawa et al., 2010; Shang et al., 2010). Studies so farhave shown that WRKY genes are induced by a variety of stress conditions andoverexpression of some these WRKY genes altered plant stress tolerance via ABA- mediated signaling. Evidence was provided by Zhang et al., (2004) that a WRKYprotein is able to activate the promoter of an ABA-inducible gene. The AtWRKY40,AtWRKY18 and AtWRKY60 are three WRKY genes derived from Arabidopsis, thesegenes are known to function as negative regulators of ABA signaling (Chen et al.,2010). Overexpression of ABA and gibberellin-induced WRKY genes are studies inaleurone cells of rice and barley (Xie et al., 2005; Xie et al., 2007). Involvement of anABA-inducible WRKY gene in abiotic stresses has been reported by Zou et al., (2007)in Larrea tridentate. Transgenic Arabidopsis expressing soybean WRKY20 gene hasshown enhanced drought tolerance and also found to regulate the ABA signal (Luo etal., 2013). WRKY46 was reported to involve in root growth development inArabidopsis plant under osmotic stress conditions. This event was regulated by theABA signaling and auxin homeostasis (Ding et al., 2015).Biotic stress response Most of the WRKY TFs identified so for are up-regulated under stress and playa key role in the survival of the plant. Several studies have provided direct evidence forthe involvement of specific WRKY proteins in plant biotic stress response (Sarris et al.,40 Review of literature2015). In Arabidopsis, many WRKY genes were identified participating in pathogendefense (Journot-Catalino et al., 2006; Kim et al., 2008). The number of WRKY genesis known to be induced by viruses (Pan and Jiang, 2014), bacteria (Schon et al., 2013),oomycetes (Dellagi et al., 2000) and fungi (Birkenbihl et al., 2012) infection. GhWRKY15 was identified from the cotton plant which is reported to beinvolved in the resistance to both viral and fungal pathogen in tobacco plant (Yu et al.,2012). A NtWRKY3 gene from Nicotiana tobaccum was found to be rapidly inducedupon infection with TMV (Skibbe et al., 2008). In pepper, the activation of Capsicumannum CaWRKY6 TF gene intern activates CaWRKY40, which are shown to involve inresistance to pathogen infection when inoculated with Ralstonia solanacearum (Cai etal., 2015). Expression of AtWRKY70 (Li et al., 2004) and other TFs like WRKY3,AtWRKY4 and AtWRKY41 were found to enhancing the resistance to Pseudomonassyringae (Higashi et al., 2008). In another report, the expression of GhWRKY44isolated from the cotton plant has enhanced the defense responses to pathogen infectionin transgenic Nicotiana benthamiana plants. Involvement of WRKY TFs likeWRKY46, WRKY70 and WRKY53 are known to involve in resistance towardsPseudomonas syringae infection was reported in Arabidopsis (Hu et al., 2012a). Inpepper, the overexpression of CaWRKY40 gene enhanced resistance to pathogen R.solanacearum (Dang et al., 2013). Abiotic stress response Currently, researchers have focused on the functional analysis of WRKYproteins in plant responses to abiotic stress. The role of WRKYs in abiotic stressresponses has been investigated and reported previously (Liu et al., 2015b; Banerjeeand Roychoudhury 2015) . Either up regulation or down regulation of an individualWRKY gene can result in elevated abiotic stresses tolerance (Wang et al., 2013; Luo et41 Review of literatureal., 2013; Dai et al., 2015). Several abiotic stresses responsive WRKY TF familymembers have been reported, from a wide range of plants, TcWRKY53 from Thlaspicaerulescens (Wei et al., 2008), OsWRKY45 from rice (Qiu and Yu, 2009)TaWRKY2and TaWRKY19 from wheat (Niu et al., 2012).AtWRKY75 was derivedfrom Arabidopsis plant in response drought stress (Archana et al., 2009), Luo et al.,(2013) have reported that expression of WRKY20 TF gene derived from wild soybeanhas improved the drought tolerance in transgenic Arabidopsis plant through ABA- mediated signaling. A WRKY46 TF was known to involve in lateral root developmentin Arabidopsis plant under osmotic stress and salt stress conditions was reported byDing et al., (2015) Few WRKY family proteins like WRKY6, WRKY30, WRKY46, WRKY28, andWRKY22 was isolated during oxidative stress induced by methyl viologen (MV) inArabidopsis (Scarpeci et al., 2008). Transgenic Nicotiana benthamiana plantexpressing Cotton WRKY Gene GhWRKY41 gene has shown enhanced droughttowards drought and salinity (Chu et al., 2015).Transgenic Arabidopsis plantexpressing GsWRKY20, a WRKY gene isolated from Glycine soja, was found to be apositive regulator involving in drought stress response and tolerance (Luo et al., 2013).Genetic engineering approaches for abiotic stress toleranceGenetic engineering has become an important tool in obtaining geneticallymodified plants with desired traits (Mittler and Blumwald, 2010; Lawlore, 2013). Theplant transformation involves the manipulation and analyzing the genes, which is notpossible through conventional breeding methods (Potenza et al., 2004). Throughtransgenic approach either a single gene or more than one gene, (multiple genecassettes) coding different proteins can be introduced to confer stress tolerance (Gosalet al., 2009; Vemanna et al., 2013). 42 "