Effects of silicon on growth, root anatomy, radial oxygen loss (ROL) and Fe/Mn plaque of Aegiceras corniculatum (L.) Blanco seedlings exposed to cadmium

• Si prompted the development of apoplastic barriers in roots under Cd stress, which probably reduced the absorption of Cd.
• The promotion of apoplastic barrier also caused the reduction of ROL.
• Si reduced the content of Fe plaque but increased the content of Mn plaque, and increased the content of Cd on Fe/Mn plaque.

Biomass, root anatomy, the location of Cd, radial oxygen loss (ROL) and Fe/Mn plaque in Aegiceras corniculatum (L.) blanco were investigated under Si and Cd treatments. The results revealed that Si alleviated the inhibition of growth due to Cd stress. Furthermore, Si prompted the development of apoplastic barriers in roots under Cd stress. Promotion of the apoplastic barrier caused the reduction of ROL. The effect of Si on the formation of Fe/Mn plaque was contrary, but Si reduced the content of Fe plaque and increased the content of Mn plaque. However, the content of Cd on Fe/Mn plaque was significantly increased by Si, which could possibly block the absorption of Cd in the root from the growth media. The present study proposed new evidence of adaptive strategy on metal tolerance and the effect of Si on metal tolerance by A. corniculatum seedlings.