Quantitative proteomics analysis of leaves from two Sedum alfredii (Crassulaceae) populations that differ in cadmium accumulation

Due to their extraordinary capacity to hypertolerate and hyperaccumulate heavy metals in above-ground tissues, hyperaccumulator plant species have gained wide attention from researchers seeking biotechnologies to manage environmental heavy metal pollution. However, the molecular basis of hyperaccumulation is still far from being fully understood. Here, we used iTRAQ to perform a quantitative proteomics study of the leaves of Sedum alfredii (Crassulaceae) from hyperaccumulating population (HP) and non-hyperaccumulating population (NHP). A total of 248 proteins had constitutively higher levels in HP leaves than in NHP leaves. Cadmium (Cd) treatment led to the induction of 13 proteins in HP leaves and 33 proteins in NHP leaves. Two proteins were induced by Cd in both HP leaves and NHP leaves. The annotations for many of the proteins that were higher in HP leaves and proteins that were induced by Cd treatments were associated with vacuolar sequestration, cell wall/membrane modification, and plant defense. In addition to establishing a global empirical foundation for the study of proteins in S. alfredii, our findings relating to the differential constitutive and inducible expression of proteins open potential new research avenues and bolster previously reported suppositions about Cd hyperaccumulation in hyperaccumulator plants.