Assessment of lead tolerance and accumulation in metallicolous and non-metallicolous populations of Hirschfeldia incana

Abstract

Hirschfeldia incana is a pseudometallophyte belonging to the Brassicaceae family identified in a lead (Pb) mining area in eastern Morocco. Growth, Pb accumulation and some physiological characteristics were compared in a metallicolous (MP) and a non-metallicolous population (NMP) of H. incana. Plants from the MP were more tolerant to Pb than those from the NMP in both soil and hydroponic culture. In hydroponic culture, when supplied with 100μM of Pb, Pb accumulation in the aboveground parts of NMP plants was 2.5 times higher than in MP plants. MP plants had significantly lower concentrations of anthocyanins and higher concentrations of chlorophyll a than NMP. Molecular analyses revealed that HMA4 and MRP14 genes were regulated by Pb in the leaves of both MP and NMP. Interestingly, the MRP14 gene was constitutively more expressed in NMP suggesting possible adaptation of the MP via regulation of Pb accumulation. Our results show that plants from the metallicolous population has adapted to tolerate and accumulate Pb and thus have good potential for phytoremediation of Pb contaminated soil.