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Towards Engineering Smart Transcription Factors for Enhanced Abiotic Stress

later included some important crop plants such as rice, maize, soybean,

barley (Seo et al., 2012). Because of the multigenetic nature of the stress

tolerance in plants, a comprehensive understanding of stress tolerance at the

molecular level is essential (Peleg & Blumwald, 2011; Zwack & Rashotte,

2015). Mittler & Blumwald (2010) defined central dogma of abiotic research

as, “deciphering how plants sense and acclimatize to an abiotic stress and

using this knowledge to develop crops with enhanced tolerance to abiotic

stresses.” It is important to note that genetically modified (GM) crops avail­

able for commercial exploitation are based on single gene traits such as

insect resistance or herbicide resistance.

TFs hold master switches status, actively control, and regulate several

cellular and molecular processes in plant (Century et al., 2008; Hussain et

al., 2011a). Genetic engineering efforts using TFs provides a systematic

approach for improvement of crop plant to various abiotic stresses because

TFs act as central regulators of several downstream stress related genes

(Bihani et al., 2011; Datta et al., 2012; Guo et al., 2016; Hu et al., 2016; Zhu et

al., 2018; Agarwal et al., 2019; Yang et al., 2019). Therefore, comprehensive

knowledge on mechanistic regulation of TFs is important for future research

(Seki et al., 2002; Yamaguchi-Shinozaki & Shinozaki, 2006). Moreover,

genetic engineering of transcriptional networks seems to be a more precisely

predictable and practical strategy compared to single structural gene engi­

neering because of the multigenic nature of stress tolerance. Therefore,

vast research data conclusively declared genetic engineering of TFs as an

excellent approach for handling complex traits such as stress tolerance in

crop plants (Century et al., 2008; Bhatnagar-Mathur et al., 2014; Hong et

al., 2017). Several studies have shown promising results in improving crop

tolerance to different stresses under controlled and field conditions (Hsieh et

al., 2013; Liang et al., 2016). Seki et al. (2002) using Arabidopsis plant and

high throughput microarray tool studied expression profile of several thou­

sand genes (over 7,000 genes) and found that genes showing upregulation

under various stresses belong to important families of TFs such as AP2/ERF,

WRKY, MYB, NAC, HD-Zip, and bZIP (Ying et al., 2012; Zhu et al., 2018).

Several members of TFs families, such as NAC, AP2/ERF, bZIP, and WRKY

have been studies in transgenic model and crop plants demonstrated their

involvement in adaptive responses to different abiotic stresses (Singh et al.,

2002; Rushton et al., 2010). In this context, huge progress has been achieved

by overexpressing different TFs genes in plants and exposed to multiple

stresses (Saad et al., 2013; Xiong et al., 2014; Fang et al., 2015; Huang et

al., 2015; Casaretto et al., 2016; He et al., 2016; Rahman et al., 2016; Zhang