Accumulation of antioxidants in rice callus (Oryza sativa L.) induced by β-glucan and salt stress

Abstract

Salinity stress causes a considerable reduction in callus growth. Mushroom polysaccharides (beta-glucan) are the most promising groups of antioxidant compounds. An in vitro experiment was conducted to evaluate the potential function of exogenously applied beta-glucan in alleviating the accumulation of antioxidants in rice callus. In this study, morphological, chemical, and biochemical parameters of an embryogenic callus of the rice variety, MR269, were investigated under 200mM NaCl stress conditions after pre-treatment with (0, 0.5, 1 and 1.5 mg/L) beta-glucan in culture media. The present study sought to evaluate chemical, biochemical, and callus growth characterization. The results revealed that callus exposed to stressful media exhibited a significant decrease in callus growth and contents of K+ and Ca+2. In addition, significant accumulation of Na+ and Na+/K+ was found, as well as an enhanced enzymatic antioxidant system and elevated proline activities under NaCl conditions. Furthermore, exogenous addition of beta-glucan at 0.5-1.5mg/L under NaCl stress induced a pronounced, significant increase of callus growth, K+ and Ca+2 contents, and enzymatic antioxidant and proline activities. In contrast, a significant decrease was found in the levels of Na+ and Na+/K+, particularly in callus treated with NaCl. beta-Glucan ameliorates the adverse effects of NaCl stress, and the extent of amelioration depends on the type of beta-glucan agent as well as treatment duration (three months). The changes mentioned are important for determining the morphological, chemical, and biochemical parameters of salinity tolerance in callus. This study demonstrated that exogenous beta-glucan exhibits alleviation of the harmful effects of salt stress and increases salinity resistance in callus rice.