The influence of flavonoid amendment on the absorption of cadmium in Avicennia marina roots

• Flavonoids acted only on symplasm transport when roots take up the heavy metal Cd2+.
• Flavonoids enhanced the tolerance of A. Marina roots to cadmium.
• The Ca2+-channel was not the unique means for Cd2+ uptake in A. Marina.
• A Michaelis–Menten kinetic model was suitably to describe Cd2+ uptake in A. Marina.

Flavonoid is a key factor for the tolerance to cadmium in plants. Concentration-dependent kinetics experiment was conducted to investigate the influence of flavonoid amendment on the Cd2+ uptake in Avicennia marina (Forsk) Vierh. roots. We found that compared with the control, saturation concentration and maximal absorption rate of Cd was higher under flavonoid amendment (p<0.05). When roots were exposed to ion transport inhibitor (LaCl3), flavonoid amendment also facilitated Cd transport in roots. Flavonoids had no influence on Cd2+ uptake in root cell walls. In conclusion, flavonoids enhance the tolerance to Cd and have a significant stimulative effect on symplasm transport of Cd in A. marina roots. Ca2+-channel was not the unique means of symplasm transport for Cd2+ absorption.