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Towards Engineering Smart Transcription Factors for Enhanced Abiotic Stress

Wyn Jones, 1994; Papageorgiou & Murata, 1995; Nuccio et al., 1998, 1999;

McNeil et al., 2000, 2001; Sakamoto & Murata, 2001), trehalose (Singer &

Lindquist, 1998; Goddijn and van Dun, 1999; Yeo et al., 2000; Iturriaga et

al., 2000; Karim et al., 2007; Paul et al., 2008), proline (Kishor et al., 1995;

Yoshiba et al., 1997; Fujita et al., 1998; Kumar et al., 2003; Claussen, 2005;

Chen et al., 2009), trigonelline (Nomura et al., 1995; McNeil et al., 1999,

2000, 2001; Nuccio et al., 1998, 1999) and sugar alcohol/polyols (Thomas

et al., 1995; Bohnert & Jensen, 1996; Smart & Flores, 1997; Sheveleva et

al., 1998; Rajam et al., 1998) have been characterized in plants under stress.

Based on the above discussion, it is easy to conclude that osmoprotec­

tants accumulate in plants under stress is generally taken as a protective

approach leading to plant survival in changing climate (Hussain et al., 2012).

However, it is also known that several important crop plants do not synthe­

size or accumulate these osmolytes in high quantity under stress. Therefore,

the generation of transgenic plants overexpressing specific osmolytes genes

is widely adopted strategy around the globe. Transgenic manipulation of

these genes serves as a suitable tool to raise crop plants with enhanced toler­

ance to various stresses. Metabolic engineering of osmolyte/osmoprotectant

genes has got momentum several successful examples can be coined where

different genes encoding osmoprotectants have been overexpressed, like

glycine betaine (Su et al., 2006; Park et al., 2007; Ahmad et al., 2008; Yang

et al., 2008; Zhou et al., 2008; Yu et al., 2009; Goel et al., 2011; Luo et

al., 2012), proline (Kumar et al., 2010; Thippeswamy et al., 2010; Jazii et

al., 2011; Karthikeyan et al., 2011; Behelgardy et al., 2012; Li et al., 2013;

Mehboobeh & Akbar, 2013; Guerzoni et al., 2014; Liu et al., 2014; Shrestha

et al., 2014; Reddy et al., 2015; Zhang et al., 2015; Guan et al., 2018, 2019;

Wang et al., 2019), trehalose and sugar alcohols (Almeida et al., 2007; Karim

et al., 2007; Stiller et al., 2008; Suzuki et al., 2008; Suárez et al., 2009;

Krasensky et al., 2014; Wang et al., 2020). Vast data have highlighted the

importance of different osmolytes/compatible solutes/osmoprotectants in

plant tolerance to various stresses and successfully demonstrated that genetic

manipulation for accumulation of these compounds has potential applica­

tions in developing stress-tolerant plants (Alzahrani, 2021).

Major stress-associated proteins include heat shock proteins (HSPs),

late embryogenesis abundant (LEA)-type proteins, and cold shock-domain

family proteins (CSPs) accumulate during various abiotic stresses such as

drought, high salt, oxidative stress, and heat stress (Volkov et al., 2006; Sato

& Yokoya, 2008; Jiang et al., 2009; Jyothsnakumari et al., 2009; Liu et al.,

2010). These proteins function as molecular chaperones, which are involved