Phosphorus protects against cadmium-induced phytotoxicity by stimulating plasma membrane H+-ATPase activity

Proper plant nutrition can be an effective strategy to alleviate the phytotoxicity and damaging effects of Cd stress on plants and to avoid its entry into the food chain. This study aimed to investigate effects of phosphorus concentrations, and pH levels in the nutrient solution on Cd uptake, growth, photosynthetic characters, total phytochelatins (PCs), and plasma membrane ATPase activity of sugar beet (Beta vulgaris L.) plants grown in sand culture. Two successive experimental studies were carried out under controlled conditions. In the first study, 10-day-old sugar beet seedlings were irrigated with a half-strength Hoagland and Arnon nutrient solution, adjusted to different pH (3.5, 5.0, 6.0, 7.0, or 8.0), and containing 0, 0.15, or 0.30 mg Cd L-1 as CdCl2. In the second study, 10-day-old sugar beet seedlings were irrigated with the same nutrient solution (pH 6), but combined with different phosphorus concentrations (0, 10, 25 and 50 mu g P ml(-1) as KH2PO4) and Cd levels (0, 0.15, and 0.30 mg Cd L-1 as CdCl2). The first study revealed that pH had a strong influence on Cd uptake by sugar beet roots. Cd stress significantly decreased sugar beet growth and Mg2+-ATPase activity, whereas it increased total phytochelatins (PCs). Second study indicated an antagonistic effect between P and Cd. Furthermore, phosphorus had the potential to stimulate Mg2+-ATPase activity and synthesis of photosynthetic pigments and to promote growth of sugar beet seedlings. Cadmium induced phytotoxicity in sugar beet seedlings can be alleviated by a proper pH and phosphorus nutrition.

Automated summary

Proper plant nutrition is important for reducing the toxic effects of Cd stress on plants and preventing its entry into the food chain. This study investigated the effects of phosphorus concentrations and pH levels on Cd uptake, growth, and photosynthetic characteristics of sugar beet plants grown in sand culture. The results showed that pH significantly influenced Cd uptake by sugar beet roots, and Cd stress reduced growth and Mg2+-ATPase activity while increasing total phytochelatins (PCs). Additionally, phosphorus had a stimulating effect on Mg2+-ATPase activity, synthesis of photosynthetic pigments, and growth of sugar beet seedlings. Proper pH and phosphorus nutrition can alleviate Cd-induced phytotoxicity in sugar beet seedlings.