*4.1. Plant Materials*

The plant materials were preserved in Nanjing Botanical Garden Memorial Sun Yat-Sen. Selected seeds of *I. lactea* were cultivated under a photoperiod of 16/8 h (day/night) in a greenhouse incubator for 6 weeks. Seedlings about 10 cm high were washed and transferred to 50 mL centrifuge tubes containing 1/2 Hoagland solution (Table S1) for 1 week. Following that, the seedlings were transferred again to centrifuge tubes containing 1/2 Hoagland solution with 50 μM CdCl2, as described in a previous study [21]. The roots were sampled at time points of 0, 1, 3, 6, 12 and 24 h, with three biological replicates for each time point. Samples at 0 h served as controls. All sampled plant materials were immediately frozen in liquid nitrogen and stored at −80 ◦C.

Tobacco (*Nicotiana benthamiana*) and *A. thaliana* (ecotype Columbia) seeds were selected and sown in plastic pots containing mixed culture medium (peat, vermiculite and perlite, 1:1:1 by volume) after soaking in sterile water for 24 h. The leaves obtained were used for research on subcellular localization and BiFC testing. Transgenic and WT *A. thaliana* seeds were prepared and sterilized with 10% NaClO for 10 min, then sown in 1/2 Murashige and Skoog (1/2 MS) medium supplemented with 3% (*w*/*v*) sucrose and 0.8% agar, incubated in darkness at 4 ◦C for 24 h and grown in a sterile environment.
