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ABSTRACT
Siegesbeckia orientalis L. is a promising species for cadmium (Cd) phytoextraction with large biomass and fast growth rate, while little information about their intracellular mechanisms involved in Cd tolerance and detoxification has been explored. A soil pot experiment with total target Cd concentrations of 0, 10, 50, 100, and 150 mg kg−1 were designed to investigate the subcellular distribution, chemical forms and thiol synthesis characteristics of Cd in S. orientalis. More than 90% of Cd was bound to the soluble fractions (48.4–76.5%) and cell walls (19.9–46.3%). Increasing soil Cd concentrations enhanced Cd sequestration into the cell walls. Most of the Cd (69.8–82.7%) in the plant organ was mainly in the forms of pectate and protein integrated Cd and undissolved Cd phosphate, while a minor portion (6.8–20.9%) was in the forms of the inorganic Cd and the water soluble Cd. Nonprotein thiols and phytochelatins significantly increased with increasing soil Cd treatment levels, while glutathione concentrations had no obvious change trends. Therefore, intracellular detoxification mechanisms of Cd in S. orientalis mainly rely on formation of less toxic Cd chemical forms, store of a large amount of Cd in cell wall and synthesis of thiol compounds.
Conflict of interest
The authors declare that they have no conflict of interest.
Acknowledgments
This study was supported by the Projects of Sci-tech Support, Sichuan, China (No. 2014NZ0044), and the Projects of National Sci-tech Support, China (2012BAD14B18-2). The authors also acknowledge the contribution of Zhu Sun, Yulan Deng, Qinglin Huo, Yuanyuan Dong, and Yuhao Zhang of Sichuan Agricultural University in supporting the investigation.