Note: Numbers are based on both literature search and bioinformatic analysis. Query Cd transporter genes are listed in Table S1. Genome sequence data were downloaded from oneKP database. Genesis software was used to estimate the similarity between protein sequences. Candidate protein sequences were selected by BLASTP searches which satisfied E value <10^-10 and query coverage >50%. The abbreviations are: NRAMPs, Natural Resistance-Associated Macrophage Proteins; HMAs; Heavy Metal ATPases; ZIPs, Zinc/Iron-regulated transporter-like Proteins (ZRT1/IRT1-Like Protein); CDFs, Cation Diffusion Facilitators; OPTs, Oligopeptide transporter family; ABCCs, ATP-binding cassette subfamily C proteins; CAXs, Cation/H+ Exchangers.