Exogenous ATP triggers antioxidant defense system and alleviates Cd toxicity in maize seedlings

The role of exogenous adenosine 5 '-triphosphate (ATP) in the regulation of antioxidant response in plants under heavy metal stress is unclear. Here, we investigated the effects of exogenous ATP application on plant growth, antioxidant response, and Cd accumulation in maize seedlings. Treatment with 0.1 mM CdCl2 moderately reduced dry weight, decreased chlorophyll content, impaired photosynthesis, and increased lipid peroxidation in maize seedlings compared with controls. However, toxicity due to Cd was alleviated after 10-200 mu M ATP treatment. Subsequently, the activity of Cd-regulated antioxidant enzymes, antioxidant metabolite accumulation, and total antioxidant capacity were drastically enhanced after 50 mu M ATP treatment. Similar patterns were observed in the ADP-treated group but not in the AMP-treated group under Cd stress. However, the ATP-induced elevation in antioxidant defense ability was decreased by the inhibition of NADPH oxidase (NOX). ATP-induced elevation in NOX activity and H2O2 production was partly reversed by the inhibition of NOX in maize seedlings under Cd stress. Furthermore, ATP promoted Cd accumulation in the roots and shoots of maize seedlings. However, the ATP-induced increase in Cd accumulation was partly abolished by the inhibition of NOX. To our knowledge, this is the first report on the role and mechanism of exogenous ATP in regulating plant growth, antioxidant response, and heavy metal phytoextraction. The study provides a new method based on exogenous ATP for enhancing heavy metal tolerance in plants.

Automated summary

The role of exogenous ATP in regulating antioxidant response and Cd accumulation in maize seedlings under heavy metal stress was investigated. The results showed that ATP alleviated Cd toxicity, enhanced antioxidant defense ability, and promoted Cd accumulation. This study provides new insights into enhancing heavy metal tolerance in plants through exogenous ATP application.