Heat priming in seeds induces antioxidant defense in maize seedling

ML EGGEL; MV PÉREZ CHACA; LB PENA

Rosario

Congreso; XXXIV Reunión de la Sociedad Argentina de Fisiología Vegetal; 2023

Sociedad Argentina de Fisiología Vegetal

Most of the varieties of agricultural plants use seeds to reproduce, however, unfavorable environmental conditions can modify their germination capacity. Different priming techniques: osmo, hydro, chemical, hormonal and nutrient techniques have been used to improve seed germination and crop yield. Stress is considered as a significant deviation from optimal living conditions. Oxidative stress is produced by the imbalance between the generation of reactive oxygen species (ROS) and antioxidant defenses, which can lead to cellular dysfunction when cells are unable to efficiently regulate ROS levels or adequately remove or replace damaged macromolecules. The objective was to evaluate the oxidative metabolism, determining ROS effect on oxidative damage and antioxidant defenses, in seedlings roots in the post-germination stage of seeds with and without pre-treatments. Maize seeds (Zea mays L.) were subjected to pre-treatment with 40 or 50 °C for 3 and 7 d. Seeds with and without heat-priming were superficially disinfected and germinated on cotton and paper towel wetting at 28 °C for 96 h. The determinations were made using the apical 2 cm of the roots. Catalase (CAT), guaiacol (GPX), ascorbate peroxidases (APX), and superoxide dismutase (SOD) activities were determined. Macromolecules damage was measured as thiobarbituric acid reactive substances (TBARS) and carbonyl group content (COOH). Root growth was induced by heat-priming at 40 °C. Thermal pre-treatments modified redox balance modified GPX, APX, CAT, and SOD activities significantly. On the other hand, pre-treatments at 50 °C showed an increase in TBARS and COOH, and reduced total -SH groups. Thus, pre-treatment at 40 °C for 3 d didn’t modify ascorbate and proline contents. According to these results, we propose that seeds primed at 40 °C have induced antioxidant enzymatic defense that would limit oxidative damage to macromolecules in maize seedlings.