Lead tolerance of Laguncularia racemosa is associated to high proline accumulation and high antioxidant capacities.

Mangrove forests are threatened by the continuous discharge of inorganic pollutants and studies show that coasts receive high levels of heavy metals, from which lead (Pb) is one of the most persistent and toxic. In the present study, lead accumulation capacity, as well as its toxicological effects and tolerance mechanisms, such as proline accumulation and increased antioxidant capacity were evaluated in two contrasting mangrove species: Avicennia germinans and Laguncularia racemosa. Six-month-old plants were exposed to different concentrations of lead nitrate (0, 75, 150, and 300 µM) and samples of roots and leaves were taken from all treatments at different times during a 30d exposure period.