Changes in antioxidant enzyme activities and gene expression profiles under drought stress in tolerant, intermediate, and susceptible wheat genotypes

Drought is a common abiotic stress that influences crop production to a large extent all over the world. Wheat crop experiences drought at main stages during its life cycle, which induces oxidative stress in the plants. The antioxidant mechanisms of the plant have a significant role in providing tolerance against the water stress. The objective of this work was to investigate the antioxidant activity and transcript profile of antioxidant enzyme related genes in three wheat genotypes to be TN4228 (drought tolerant), TN1399 (moderately tolerant) and TN3737 (susceptible) at control [80% Field capacity (FC)] medium (40% FC) and severe stress (25% FC). Water-limited conditions led to a decrease in relative water content (RWC). However, drought increased malondialdehyde (MDA), hydrogen peroxide (H2O2), proline content, and antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX)]. In addition, we observed the enhancement of the delta-1-pyrroline-5-carboxylate synthase (P5CS), CAT, APX and SOD gene expressions at drought stress conditions. Both moderate and severe stresses caused genotype-specific responses, which were dependent on stress severity. According to drought stress and defense systems in TN4228, it was obtained that the engaged genes and enzymes play significant roles in defense responses and could be viable targets to determine the level of drought tolerance.