178

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

rice having introduced genes, i.e., OsNAC6 SNAC1, and SNAC2, is tolerant

to rice plants’ drought stress compared to the non-transgenic rice (Todaka

et al., 2015). Research showed that transgenic plants with the TaNAC67

gene are tolerant to drought stress and update physiology and metabolism

(Sharma et al., 2017).

A set of hydrophilic proteins like LEA proteins are responsible for the

multiple abiotic stress like salt, heat, drought, and cold stresses in crop plants

(Banerjee & Roychoudhury, 2016). Therefore, transcription factors are the

most vital element to induce abiotic stress in a crop plant by transgenic

approaches.

6.5.3.2.2 Transgenic Approaches for Heat Stress

Heat stress is vital abiotic stress which affects the crop yield and physi­

ological traits of crop plants (Zhu, 2016). Heat stress decreases the rate of

photosynthesis, damages the cell membranes, and decreases the activity of

reactive oxygen species (Dwivedi et al., 2016). The level of reactive oxygen

species exceeding a certain limit will cause protein denaturation and decrease

protein homeostasis. Transgenic approaches have made plant efficient and

effective reactive oxygen species scavenging ability as it is a part of the

signaling pathways as their level exceed the limit. These are effectively

scavenged via antioxidant enzymes like glutathione reductase (GR), catalase

(CAT), superoxide dismutase (SOD), and peroxidase (POX) (Fancy et al.,

2017). ROS-scavenging enzymes in transgenic plants is a way to tackle

high-temperature stress which causes oxidative disintegration in crop plants.

Transgenic apple plants having cytosolic ascorbate peroxidase (cAPX)

can minimize cell membrane damage and increase the photosynthesis rate

(Zandalinas et al., 2018). Transgenic tomato plants comprising the cAPX

gene can tolerate high-temperature stress up to 40°C in field conditions with

minimum heat stress oxidative injury compared to the non-transgenic tomato

plant (Sadiq & Akram, 2018). In many types of research, transgenic tomatoes

having polyamine expressed tolerance against the heat stress; expression of

the S-adenosyl-I-methionine decarboxylase from Saccharomyces cerevisiae

led to the manufacturing of polyamines which made tomato plant tolerant

to high-temperature stress (Parmar et al., 2017). Similarly, the Transgenic

potato plant having Cu/Zn SOD taken from the okra plant can tackle high-

temperature stress by activating many reactive oxygen species – scavenging

enzymes compared to the non-transgenic potato (Sadiq & Akram, 2018).