Role of sulfur in pyrroline-۵-carboxylate synthase (P۵CS) gene expression, proline accumulation, and antioxidant enzyme activity of wheat under water deficit conditions

Sulfur (S) plays a crucial role in plant growth and development and serves numerous biological functions in plants. To investigate the role of sulfur in drought stress protection, two experiments were conducted under greenhouse and growth  chamber conditions in ۲۰۲۱ Also, to evaluate  the influence of foliar application of sulfur on the expression of Pyrroline-۵-carboxylate synthase, )P۵CS) , proline concentration, and antioxidant enzyme activities , the plants of wheat Sardari and Ivan cultivars were exposed to two levels of water regimes. Plants under well-watered irrigation and drought stress conditions showed different P۵CS expression levels and accumulated proline. The P۵CS expression level in the Ivan cultivar was significantly increased by foliar application of S, while the same application had no significant effect on P۵CS expression in the Sardari cultivar. Plants exposed to drought stress and foliar-sprayed with S showed a higher proline accumulation The activities of antioxidant enzymes, including peroxidase (POD), catalase, glutathione peroxidase (GP), and glutathione reductase , were increased by ۱۳۴ %, ۴۰.۴ %,  ۴۵.۴ %, and ۷۷.۴ %, respectively, in plants exposed to drought stress. POD and GR were significantly increased by ۱۹.۶ % and ۵۱.۸ %, respectively, due to S application. Drought-induced plants that were foliar-sprayed with S exhibited a significantly lower rate of ion leakage and higher leaf-relative water content than those of control plants. Based on the results of the present research, it was revealed that S substantially enhances the expression rate of the P۵CS gene, leading to proline accumulation, and activates defense reactions in water-stressed wheat.

Keywords:

antioxidant enzymes , Proline , Pyrroline-۵-carboxylate synthase , Sulfur