Proteomics-based analysis on the stress response mechanism of Bidens pilosa L. under cadmium exposure

Bidens pilosa L. (B. pilosa) has great potential for the phytoremediation of cadmium (Cd)-contaminated soils. However, the molecular mechanism underlying Cd tolerance and detoxification in B. pilosa is still unclear. In the present study, a 4D label-free quantification technique combined with liquid chromatography-parallel reaction monitoring mass spectrometry was used to explore the stress response mechanism of B. pilosa. Proteomic analysis revealed 213 and 319 differentially expressed proteins (DEPs) in the roots and leaves of B. pilosa, respectively, and 12 target proteins were selected for further analysis. SWISS-MODEL was used to predict the 3D structures of the target proteins. The cation-ATPase-N structural domain and an ATPase-E1-E2 motif, which help to regulate ATPase function, were detected in the TR10519_c0_g1_ORF protein. In addition, the TR6620_c0_g1_ORF_1 and TR611_c1_g1_ORF proteins contained peroxidase-1 and peroxidase-2 motifs. The TR11239_c0_g1_ORF protein was found to belong to the Fe-SOD family, to have a dimeric structure and to contain a relatively high proportion of α-helices but few β-sheets, which play important roles in reactive oxygen intermediate scavenging. Thus, the current study provides an overview of the proteomic response of B. pilosa in scavenging of Cd-induced reactive oxygen intermediates and reveals key proteins involved in the stress response of B. pilosa under Cd exposure.