Interaction between heavy metal pollutants (Cd and Zn) is influenced by the presence of salinity in the halophyte plant species Kosteletzkya pentacarpos

Coastal areas in the world are not only suffered from salinization but are also contaminated with high amounts of heavy metals resulting from human activities. Kosteletzkya pentacarpos is a promising wetland halophyte plant species for phytomanagement of heavy metal-contaminated salt areas. However, in previous work, K. pentacarpos was exposed to one single heavy metal, and was cultivated in nutrient solution only. Hence the global aim of the present study is to assess the response of K. pentacarpos to a complex heavy metal pollution implying the simultaneous presence of Cd and Zn excess, to understand the putative influence of NaCl on the plant physiological and biochemical behaviour, and to compare the plant behaviour in nutrient solution and in contaminated soil. In our study, combination of Cd and Zn increases heavy metal concentrations in all organs with accumulation of Cd mainly in the cell walls and even distribution of Zn between symplasm and apoplasm. Heavy metal accumulation reduces net photosynthesis, leading to a heavy metal-induced oxidative stress. Combined treatment also induces a specific plant hormonal status in K. pentacarpos which could not be fully explained by an additive effect of Cd and Zn. Heavy metal stress reduces osmotic potential through osmolytes (proline and glycinebetaine) accumulation and modified metabolism. The addition of NaCl reduces the heavy metal absorption, resulting in alleviation of oxidative stress and modification of phytohormoneal status. In contaminated soil, combination of heavy metal affects plant growth, development and flowering. Cultivation of K. pentacarpos changes the bioavailability of heavy metal and reduces the volume of leachate as well as their heavy metal concentration in response to NaCl. It is concluded that K. pentacarpos is a promising candidate for revegetation of multiple heavy metals contaminated areas, especially under salt stress conditions.(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 201