Diurnal Temperature-Related Dynamics of Glutathione Reductase Activity in Wheat Genotypes Under Drought

Abstract

The strategically important wheat plant is the most cultivated of cereals. Drought is one of the main factors adversely affecting its productivity and quality of grain. Components of the ascorbate-glutathione cycle play an important role in the antioxidant defence system. The diurnal dynamics of temperature-related glutathione reductase activity (GR), one of the main components of the antioxidant defence system, were studied in durum (Barakatli 95, Garagylchyg 2) and bread (Gobustan, Tale 38) wheat genotypes of contrasting tolerance, when exposed to sustained soil drought. Glutathione reductase is highly sensitive to glutathione. Leaf samples were taken at the end of the wax ripening phase at three-hourly intervals (800, 1100, 1400, 1700), frozen in liquid N2, and kept at -800C. The experiments indicated that GR activity increased in stressed, tolerant, (Barakatli 95, Gobustan) and decreased in stressed sensitive varieties (Garagylchyg 2, Tale 38) compared with watered variants. In the samples taken at 1100, enzyme activity increased in all the genotypes, compared with the control. However, in the Gobustan genotype the activity of the enzyme remained almost constant. At the highest temperatures (1400) GR activity decreased by almost 50% both in durum and bread wheat varieties compared with the control. At 1700 GR activity increased in durum wheat genotypes and remained at a low level in bread wheat genotypes. Thus, durum wheat genotypes have a stronger defence system against unfavourable environmental conditions compared with bread wheat genotypes.