Antioxidant response mechanism in leaves of tomato plants subjected during flooding and post-flooding stress

CHAVEZ, CÉSAR; MIGNOLLI, FRANCESCO; MEDINA, RICARDO; VIDOZ, MARÍA LAURA

Congreso; XXXIV Reunión Argentina de Fisiología Vegetal; 2023

Flooding events have increased in frequency and intensity in recent years due to climate change threatening sensitive crops such as tomato. Flooding stress hampers photosynthesis and gas exchange, as well as causes oxidative stress due to the accumulation of reactive oxygen species (ROS). Plants can scavenge ROS by synthesising and activating enzymatic antioxidants (EAs) and non-enzymatic antioxidants (NEAs). Although this response has been studied in various biological systems during flooding, little is known about the events that take place when the water recedes. In this study, we analysed the content of NEA and the EA activity in tomato plants during flooding and post-flooding stage. Four-week-old tomato plants (cv Ailsa Craig) were submerged in water up to the cotyledonary node. After six days of flooding, water was drained, and plants were kept at field capacity for six days more. Analysis of NEA (total phenolic compounds, flavonoids, anthocyanin, ascorbic acid and glutathione) and EA (superoxide dismutase SOD, catalase CAT, ascorbate peroxidase APX and glutathione reductase GR) were performed. During flooding, total phenolic compounds, flavonoids, anthocyanin, and ascorbic acid but not glutathione increased significantly as well as SOD and CAT activity. During post-flooding NEAs remained significantly higher than in controls as opposed to anthocyanins and glutathione. The activity of APX, GR and SOD was as low as controls while CAT remained activated. These results suggest that NEAs and CAT could be the primary mechanism to scavenge ROS both in flooding and post-flooding stages. The increase in ascorbic acid contents was not associated with a change in glutathione and APX activity. This suggests that ascorbic acid might not be involved as an electron donor for the dismutation of superoxide ions, and a direct antioxidant action is proposed.