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

In plants PDH45, and the OsCPK12 gene maintains ROS make the plant

tolerant to salt stress (Reddy et al., 2017).

6.2.2 DROUGHT

Osmotic stress in plants is also due to the low water availability. In drought

conditions, the late embryogenesis abundant (LEA) proteins are responsible

for protecting plant against desiccation. Expressions of LEA class genes

results to enhance tolerance against water stress. In transgenic Arabidopsis,

the gene that codes galactinol synthase involved in synthesizing oligosac­

charides belongs to family raffinose to enhance tolerance against drought.

During drought conditions, raffinose acts as an osmoprotectant and decreases

cellular damages in plant (Shinozaki & Yamaguchi-Shinozaki, 2007). MsrB2

gene produce tolerance against drought by minimizing oxidative injury of

ROS. The rice drought-tolerant gene CaMsrB2 is taken from Capsicum

annuum, making transgenic rice drought tolerant (Nahar et al., 2016).

6.2.3 HIGH TEMPERATURE

Cell membrane thermostability is a checkpoint of heat stress tolerance

in plants. In many types of grass, the genetic cause of many heat shock

proteins (HSPs) has been identified by co-segregation and QTL analyzes.

In grasses, tolerance to heat stress is not regulated by a single gene (Maestri

et al., 2002). Heat stress in plants leads to express genes related to HSPs.

Therefore, heat shock factors get attached to Heat Shock Elements’ binding

site in the promoters of heat shock genes, including the HSPs’ expression

on high-temperature stress. HSPs play an important role as chaperones and

are involved in saving the plant’s intracellular proteins by keeping intact the

functioning and structural stability of plant cells. Based on molecular weight,

HSPs are classified into various groups, viz., HSP20, HSP70, HSP100,

HSP60, and HSP90. HSP with low molecular weight showed diversity

among other HSPs (Hasanuzzaman et al., 2013).

In Arabidopsis HSP101, and HSP70 proteins are responsible for gener­

ating tolerance in plant against heat stress. In the wheat plant following genes,

HSP101 members, Tahsp101c, Tahsp101b, and Tahsp101a, have been intro­

duced to develop tolerance against high-temperature stress (Maestri et al.,

2002). H2O2-responsive ANP1/NPK1 gene in tobacco can develop heat stress

in plants. APX1 gene in barley is responsible for heat tolerance compared to