O in bread wheat Triticum

this amount recovered relatively in the Gobustan variety, while remained unchanged in Tale 38. 
Activities of APX and GR, which are the main enzymes of the ascorbate-glutathione cycle, were 
different in various genotypes. The activities of these enzymes in bread wheat genotypes decreased 
sharply (about 2 times) and increased after rewatering. In this case, the GR activity reached the 
control value, whereas the APX activity was lower compared with the watered variant. The results 
clearly indicated that the ASC-GSH cycle responded differentially in drought-tolerant and drought-
sensitive wheat genotypes during drought and recovery.
 
Keywords: Drought, rehydration, ascorbate peroxidase, ascorbic acid, glutathione reductase, reduced 
glutathione, H
2
O
2 
 
 
INTRODUCTION 
 
The climate changes caused by rising 
temperatures on Earth increase the impact of abiotic 
stressors. Drought is considered the most dangerous 
among abiotic stresses. Because the plant 
temperature increases along with the weakening 
physiological and biochemical processes under 
drought (Medvedev, 2013). Due to population 
growth, there is a growing interest in the production 
of strategically important nutrients. Various studies 
have been carried out for the acclimatization and 
increase of productivity of bread and durum wheat 
genotypes grown in the Azerbaijan territory (Aliyev 
et al., 2014; Huseynova et al., 2015). Reactive 
oxygen species (ROS), such as H
2
O
2
, ̇ O₂¯, OḢ are 
formed in plants under normal conditions (light, 
water, temperature) but the plant antioxidant 
defense system can neutralize these substances in 
small amounts (Zhou et al., 2019). When the ratio 
between the formation and neutralization of ROS 
under stress conditions is violated, the plant is 
exposed to oxidative stress. The AsA-GSH pathway 
(Asada-Halivel), which is one of the antioxidant 
defense systems, plays an important role in the 
neutralization of ROS (Noctor and Foyer 1998). 
This cycle includes four enzymatic (ascorbate 
peroxidase, 
monodehydroascorbate 
reductase, 
dehydroascorbate reductase, glutathione reductase) 
and three non-enzymatic (ascorbic acid, reduced 
glutathione, 
hydrogen 
peroxide, 
phenolic 
compounds, and etc.) antioxidant substances. 
Despite the detoxification, they prevent other 
harmful effects caused by abiotic stress. According 
to some authors, changes in the expression or 
regulation of the enzymes through the AsA-GSH 
pathway decrease the amounts of ROS in the plant 
and makes it tolerant to abiotic stresses
(Hasanuzzaman et al., 2019, Noctor et al., 2012).