Oxidative stress in wild‐derived and cultivated peanut genotypes caused by heat stress at flowering

Abstract Peanut ( Arachis hypogaea L.) is a globally important crop; however, its productivity is increasingly threatened by heat stress, exacerbated by global warming. Developing heat‐tolerant peanuts is crucial for sustainable production amidst rising temperatures. Unlike commercial cultivars, wild‐derived peanuts possess broader genetic diversity, being naturally adapted to an array of challenging climatic conditions. Antioxidant activity and reactive oxygen species (ROS) regulation are potential indicators of heat tolerance. Studies on enzymatic activity in peanuts have focused on commercial cultivars, leaving a research gap regarding the antioxidant defense mechanism in wild relatives. This study aimed to identify peanut genotypes with superior antioxidant performance and classify their response to heat stress by increasing activity of specific enzymes to scavenge ROS. The experiment was conducted in growth chambers, using 20 peanut genotypes, 12 wild‐derived and eight commercial cultivars. Heat stress (35/22°C, day/night) was imposed for 7 days at 60 days after planting, following pre‐ and post‐stress conditions of 30/20°C (day/night). Leaf samples were collected before, during, and after heat stress. Enzymatic activities of superoxide dismutase, catalase, and ascorbate peroxidase, alongside hydrogen peroxide levels, were analyzed. Upregulation of antioxidant activities under heat stress and recovery periods highlighted their role in detoxifying ROS. AU NPL 17, BatKemp1, IpaCor2, IpaDur2, IpaDur3, MagDur1, and ValSten1 exhibited superior antioxidant enzyme activity, suggesting their potential for heat tolerance. Results also indicated different mechanisms used by peanut genotypes to scavenge ROS, such as balanced ROS scavenging, prioritization of peroxisomal or chloroplast/cytosol detoxification, and compensatory mechanisms.