Effect of water stress on antioxidative enzymes and glycine betaine content in drought tolerant and drought susceptible cotton (<em>Gossypium hirsutum</em> L.) genotypes

Abstract

Drought stress is one of the foremost abiotic stress, which causes a reduction in plant growth and yield. Therefore, present study was aimed to analyzed the activity of four antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), esterase (EST), and osmolyte glycine betaine (GB) in leaf and root tissues of two cotton genotypes namely, G.cot-16 (drought tolerant) and GBHV-177 (drought susceptible) subjected to drought stresses by withholding of irrigation.A differential response was observed for antioxidant enzymes and GB network in cotton genotypes. GB content was significantly higher in leaf tissues as well as root tissues of G.cot-16 than GBHV-177. The activity of SOD significantly boosted in leaf and root tissues of both the genotype up to 20 days after stress (DAS) however, further it declined in the GBHV-177 with increasing severity of water deficit stress. Activities of GR and EST significantly enhanced in leaf and root tissues of G.cot-16 while drastically declined in the leaf and root tissues of GBHV-177 till 40 DAS under water stress condition. Moreover, POD activity was significantly increased in the leaf and root tissues of G.cot-16 up to 30 DAS then it was declined to 40 DAS, however in GBHV-177 markedly declined in the leaf and root tissues till 40 DAS under water deficit stress condition. It is concluded that during water stress leaf tissues of drought-tolerant genotype shows higher reactions of an antioxidative pathway to cope up drought stress. Thus, the existence of this variability in the cotton genotypes might be used by the breeder for improvement of cotton productivity under drought or water deficit stress condition.