Effect of Salinity Variation on the Quantity of Antioxidant Enzymes in Some Rice Cultivars of North Kerala, India

Abstract

Rice (Oryza sativa L.) is one of the most popular and important cereal crops, providing the staple food for more than half of the world's population, especially those living in developing countries. Salinity is one of the prominent abiotic constraints for crop plants worldwide. It affects their growth, development, productivity and ultimately the yield. It also triggers a series of morphological, physiological, biochemical and molecular changes in plants. Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and may cause severe damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. Plants possess very efficient enzymatic and non-enzymatic antioxidant defense systems which work together to control uncontrolled oxidation and protect plant cells from oxidative damage by the scavenging of ROS. The major antioxidant enzymes include catalase, peroxidase, super oxide dismutase, glutathione reductase, glutathione peroxidase, ascorbate peroxidase, etc. Production of antiaoxidant enzymes by some native rice genotypes collected both from saline and non-saline rice tracts of Kerala State of Inda was studied presently in relation to relative induction of salt stress. All the genotypes showed significant upregulation in the production of antioxidant enzymes in response to increase in salt stress applied.

Activities of Antioxidant Enzymes in Six Rice (Oryza sativa L.) Varieties at Seedling Stage under Increasing Salinity Stress

“…Less increase of catalase was observed in Gontrabidan-2 1 (1% at 0.05 M NaCl, 4.8% at 0.1 M NaCl and 5.7% at 0.15 M NaCl), Ghewas(1.2% at 0.05 M NaCl, 5.7% at 0.1 M NaCl and 8.7% at 0.15 M NaCl) and Sadamota (0.8% at 0.05 M NaCl, 5.6% at 0.1 M NaCl and 10% at 0.15 M NaCl) over respective controls. Under salinity conditions, high activity of catalase observed in the cultivars of saline rice areas (Joseph et al, 2015), Chunthaburee et al (2016). Safeena and Bandara (2006) observed similar results in Pokkali (salinity tolerant variety) (Willekens et al, 1995).…”

“…Low levels of GR increase in case of Ghewas (1.84% at 0.05 M NaCl, 3.5% at 0.1 M NaCl and 6.8% at 0.15 M NaCl), Sadamota (1.86% at 0.05 M NaCl, 3.4% at 0.1 M NaCl and 7.7% at 0.15 M NaCl) and Gontrabidan-2 (4.8% at 0.05 M NaCl, 8.8% at 0.1 M NaCl and 12.5% at 0.15 M NaCl). Joseph et al (2015) reported that higher activities of GR noticed in rice cultivars from saline areas. Similar results were observed in tolerant pea variety under saline conditions (Hernandez et al, 2000).…”

“…Higher levels of antioxidant enzymes in the protoplasm are an important parameter in determining salt tolerance in rice (Joseph et al, 2015). Chunthaburee et al (2016) reported that categorization of rice cultivars based on antioxidant enzyme activities and physiological characters.…”

“…Above the findings from several researchers supports that higher lipid peroxidation in Ghewas, Gontrabidan-2, Sadamota leads to high oxidative damage to membranes under salt stress when compared lower levels of Lipid Peroxidation in Doosehwar, Malabati and Sadamota. Over all taken in to consideration, salt tolerance in rice seedlings is associated with higher levels of the various antioxidants and higher activity levels of the anti-oxidative enzymes SOD, CAT, POX, APX, and GR (Joseph et al,2015).…”