Differential responses of antioxidants and osmolytes in upland cotton (Gossypium hirsutum) cultivars contrasting in drought tolerance

Abstract

Major abiotic stresses affecting growth and metabolism of plants include heat and drought or water stress. In cotton, drought stress leads to limited plant growth and productivity that results in significant yield losses – up to 30% worldwide. Therefore, the present study was carried out in cotton to examine the changes in growth, physiological, and oxidative stress mechanisms in response to drought stress. Our results revealed a significant (P<0.05) decline in growth parameters such as plant height (cm), root length (cm), and relative water content (RWC) caused by drought stress. However, a significant increase (P<0.05) was observed in osmotic potential (OP), electrolyte leakage (EL), glycine betaine (GB) content, lipid peroxidation, proline content, and antioxidant enzyme activity. Two tolerant cultivars, G.Cot.16 x H-1353/10 and H-1353/10 x G.Cot.16, indicated no significant decrease in physio-biochemical traits, whereas sensitive genotypes were markedly affected during drought stress. The activity of antioxidant enzymes, such as catalase and peroxidase, increased markedly among the tolerant cultivars, but decreased in sensitive cultivars. Thus, it can be inferred that short-term drought stress severely disrupted cotton growth and metabolism, and that the apparent osmolyte accumulation and enzymatic mechanism played a critical role in protecting plants against oxidative damage.

Keywords

• Abiotic stress
• Osmotic potential
• Proline
• Catalase
• Glycine betaine