Putrescine ameliorates detrimental effects of 2,4-D herbicide on growth and antioxidant enzymes activity of tomato

ABSTRACT

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at higher doses has detrimental effects on tomato (Solanum lycopersicum L.). Putrescine (Put) mitigates 2,4-D induced damage by regulating antioxidants level. Responses of Put-treated tomato to 2,4-D induced oxidative damage through physiological activities were evaluated. Physiological and biochemical effects of concentrations of 0.5 and 1 mM (D1 and D2) of 2,4-D, with, and without, Put (0.1 mM), were compared. The high dose of 2,4-D caused declines in growth and photosynthetic pigments accompanied by decreased protein, sugar levels, and nitrate reductase (NR) activity compared to untreated plants. The high dose of 2,4-D enhanced accumulation of reactive oxygen species (ROS) with negative effects on lipid, protein contents, and membrane stability. Tomato plants were used to elucidate effects of 2,4-D generated ROS through H₂O₂ (26.9%) and malondialdehyde (MDA) (82.6%) in the plant antioxidant system. The low 2,4-D dose stimulated growth. In the presence of 2,4-D decrease in catalase activity was associated with a higher amount of thiobarbituric acid-reactive substances which cause membrane peroxidation. In Put-treated plants, deleterious effects of 2,4-D were reduced. The Put-treatment might act as a signal that reduces oxidative damage by triggering activity of antioxidant enzymes leading to improved growth and photosynthesis rate.

KEYWORDS:

• oxidative effect
• polyamine
• Solanum lycopersicum