Cadmium and zinc accumulation and tolerance in two Egyptian cultivars (S53 and V120) of <i>Helianthus annuus</i> L. as potential phytoremediator

Abstract

One of the most important oil crops in the world, sunflower (<i>Helianthus annuus</i> L.), is recognized to help in soil phytoremediation. Heavy metal (HM) contamination is one of the most abiotic challenges that may affect the growth and productivity of such an important crop plant. We studied the influence of HM-contaminated soils on metal homeostasis and the potential hypertolerance mechanisms in two sunflower Egyptian cultivars (V120 and S53). Both cultivars accumulated significantly higher cadmium concentrations in their roots compared to their shoots during Cd and Zn/Cd treatments. Higher root concentrations of 121 mg g^-1dry weight (DW) and 125 mg g^-1 DW were measured in V120 plants compared to relatively lower values of 111 mg g^-1 DW and 105 mg g^-1 DW in the roots of S53 plants, respectively. Cadmium contamination significantly upregulated the expression of heavy metal ATPases (<i>HaHMA4</i>) in the shoots of V120 plants. On the other hand, their roots displayed a notable expression of <i>HaHMA3</i>. This study indicates that V120 plants accumulated and sequestered Cd in their roots. Therefore, it is advised to cultivate the V120 cultivar in areas contaminated with heavy metals as it is a promising Cd phytoremediator.