Genome-wide identification and expression profiling of the copper transporter gene family in Populus trichocarpa

Copper transporters (COPT/Ctr) have important roles in the transport of copper (Cu) across the cell membrane in many different species. A comprehensive phylogeny and a molecular structure analysis of the COPT/Ctr family in plants and animals are presented, with an emphasis and bioinformatic analysis of the copper transporter family in Populus trichocarpa (PtCOPT). Structural analyses of PtCOPTs showed that most have 3 transmembrane domains (TMDs), with an exception of PtCOPT4 (2 TMDs). Gene structure, gene chromosomal location, and synteny analyses of PtCOPTs demonstrated that tandem and segmental duplications have likely contributed to the expansion and evolution of the PtCOPTs. Additionally, promoter analyses showed that the function of PtCOPTs is related to Cu and ferrum (Fe) transport. Tissue-specific expression of PtCOPT genes showed that most had relatively high transcript levels in roots and leaves. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed that the expression of PtCOPT genes were induced not only in limited and excessive Cu, Fe, zinc (Zn) and manganese (Mn) stress, but also in lead (Pb), and cadmium (Cd) stress.