ROLE OF MITOCHONDRIAL ALTERNATIVE OXIDASE (AOX) GENE FOR SALINITY TOLERANCE IN WHEAT CULTIVARS

Abstract

Elevated salt stress is a major constraint for wheat productivity in many countries, including Bangladesh. Laboratory an experiments was conducted in the laboratory of the Department of Biochemistry and Molecular Biology, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur-5200, Bangladesh to investigate the effect of salinity on germination and seedling growth on three varieties of wheat. BARI Gom 28 and BARI Gom25 were used on salt tolerant varieties and BARI Gom 20 (Gourab) was used as salt sensitive varieties. The experiment was laid out in a complete randomized design (CRD) with three replications and three level of salinity (0, 150 and 200 mM of NaCl). Salt stress caused a significant reduction in growth of all the wheat cultivars. Growth reduction was higher in salt-sensitive cultivar than salt tolerant one, BARI Gom 28 showed a higher salt-tolerance in all physiological parameters of wheat. There were remarkable differences in antioxidant enzymes (catalase, peroxidase and ascorbate and peroxidase) activities of wheat differing in salt tolerance. Catalase and ascorbate peroxidase activities were a significantly decreased in salt-sensitive genotype whereas significant increases were observed in salt-tolerant genotypes with the increasing salt concentration. Peroxidase activity was significantly decreased in all the salt-sensitive and salt-tolerant genotypes with increasing NaCl concentration. Interestingly, gene expression level of TaAOX1a and TaAOX1c showed higher expression in BARI Gom 28 with increasing level of salt concentration. Additionally, lower accumulations of hydrogen peroxide, malondialdehyde, and higher activities of antioxidant enzymes catalase, peroxidase and ascorbate peroxidase in the salt-tolerant BARI Gom 28 than those in the salt-sensitive Gourab indicated relatively reduced oxidative damage in BARI Gom. It may be assumed that TaAOX1a and TaAOX1c along with antioxidant enzymes played a significant role to alleviate salt stress of BARI Gom 28. Further study will be needed to explore the molecular mechanism for reducing the salt stress of wheat cultivars.