Accumulation and speciation of Cd in Avicennia marina tissues

ABSTRACT

Avicennia marina is a high-Cd-tolerant species in the mangrove wetlands. A hydroponic experiment was carried out to research the accumulation and chemical form distribution of Cd in the tissues of A. marina under different concentrations and durations of Cd stress. It was found that the concentrations of Cd in plant tissues followed the order of root > stem > leaf. The data suggested that root activity decreased, Cd accumulation ability weakened in roots, and the translocation factor increased in stems and leaves with the increase of stress duration. With a proactive defense mechanism, most Cd was bound to pectates, organic acids, and protein, especially in roots and stems with the most proportion of 88.51 and 78.91%, respectively, having lower biological activities. The Cd bounded to water-soluble organic acid and free inorganic aminophenol–Cd showed the lowest concentration. The pectates, organic acids, and protein-integrated Cd seem the most important in affecting Cd detoxification for A. marina; this mechanism of change in Cd biological activities decreases the toxicity of this aggressive pollutant and presents new knowledge about the tolerance of mangrove plants.

KEYWORDS:

• Mangrove
• Avicennia marina
• cadmium
• species distribution

Funding

This work was kindly supported by the National Natural Science Foundation of China under Grant numbers 31530008 and 31570414, and the China Postdoctoral Science Foundation under Grant number 2016M591773.

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any study with animals performed by any of the authors.