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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

2012; Baillo et al., 2019; Hrmova & Hussain, 2021). In conclusion, engi­

neering suitable TFs could potentially alleviate stress responses because they

regulate the expression of several stress-responsive downstream genes by

driving the specific regulatory elements in their promoter region (Hoang et

al., 2017; Baillo et al., 2019).

Similarly, phytohormones also have significant contribution in normal

growth and development of plants. ABA is one such hormone which play

significant role in plant growth and development especially under various

biotic and abiotic stresses (Fujita et al., 2013, 2014; Hrmova & Lopato,

2014; Hoang et al., 2019; Hrmova & Hussain, 2021). Generally, ABA is

a stress-responsive because it is involved in conferring adaptive responses

under environmental stresses (Bauer et al., 2013; Suzuki et al., 2013).

Research data have reported various Interactions between ABA and different

plant TFs under stress (Shang et al., 2010; Shan et al., 2012). Over 200

TFs of 20 gene families have been simultaneously characterized at a single

developmental stage regulated by ABA in a study (Nemhauser et al., 2006).

Based on reports, several drought-responsive genes show response to ABA

and many genes are non-responsive to ABA. Therefore, plant stress toler­

ance is governed by either ABA-dependent or ABA-independent pathways

(Yan et al., 2013; Wishwakarma et al., 2017; Baillo et al., 2019; Khan et al.,

2019; Hrmova & Hussain, 2021). However, it is indicated that potentially

huge gap exists in our understanding of stress-regulated (ABA-dependent

and ABA-independent) signaling pathways under different abiotic stresses.

However, TFs involved in ABA-dependent pathways could potentially be

the natural target for genetic engineering to enhance abiotic stress tolerance

of crop plants (He et al., 2016; Bi et al., 2016, 2017; Landi et al., 2017).

7.3 APPROACHES TO MANIPULATE GENE PATHWAYS USING

TRANSCRIPTION FACTORS FOR ENHANCED ABIOTIC STRESS

TOLERANCE

Generation of transgenic plants represents a complementary approach to

plant breeding for developing stress-tolerant crop plants, particularly drought

stress. Many studies have reported that genetically engineered plants exhib­

ited high tolerance to drought and associated stresses (Denby et al., 2005;

Vinocur & Altman, 2005; Valliyodan & Nguyen, 2006; Yang et al., 2010;

Funganti-Pagliarini et al., 2017; Wani et al., 2017). However, models’ plants

like Arabidopsis were used in most of these published results and researchers