Comparative Proteomic Analysis of Differentially Expressed Proteins in Amaranthus hybridus L. Roots Under Cadmium Stress

摘要

Amaranthus hybridus L. has great potential for use in phytoremediation of soils contaminated with cadmium Cd). In this study, we found higher absorption of Cd by the roots of A. hybridus than by its other organs. To understand the mechanism of Cd accumulation in A. hybridus roots, a comparative proteomic approach was used to differentiate the two-dimensional electrophoretic profiles of root proteins in Cd-free and Cd-treated plants. Twenty-eight differentially expressed proteins were successfully identified using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry. Of these, 10 were specifically expressed under Cd stress, and another 11 were upregulated and 7 downregulated by >2.5-fold under Cd stress. We observed increased expression of proteins involved in energy metabolism, protein metabolism, stress and defense, and signal transduction. These changes likely enhanced Cd tolerance and enrichment in A. hybridus. The downregulated proteins were mainly involved in the synthesis of microRNAs, cell walls, and other structural components. These observations were further confirmed by quantitative fluorescence PCR. The resulting differences in protein expression patterns suggest that redirection of root cell metabolism might be an important survival mechanism for A. hybridus under Cd stress.