Comparative Analysis of Cd Uptake and Tolerance in Two Mangrove Species ( and ) with Distinct Apoplast Barriers.

Mangrove plants demonstrate an impressive ability to tolerate environmental pollutants, but excessive levels of cadmium (Cd) can impede their growth. Few studies have focused on the effects of apoplast barriers on heavy metal tolerance in mangrove plants. To investigate the uptake and tolerance of Cd in mangrove plants, two distinct mangrove species, and , are characterized by unique apoplast barriers. The results showed that both mangrove plants exhibited the highest concentration of Cd in roots, followed by stems and leaves. The Cd concentrations in all organs of consistently exhibited lower levels than those of . In addition, displayed a reduced concentration of apparent PTS and a smaller percentage of bypass flow when compared to . The root anatomical characteristics indicated that Cd treatment significantly enhanced endodermal suberization in both and roots, and exhibited a higher degree of suberization. The transcriptomic analysis of and roots under Cd stress revealed 23 candidate genes involved in suberin biosynthesis and 8 candidate genes associated with suberin regulation. This study has confirmed that suberized apoplastic barriers play a crucial role in preventing Cd from entering mangrove roots.