Expression of COPTs in rice was influenced by bivalent cations. Rice variety Zhonghua 11 at the four-leaf stage grown in hydroponic culture was used for qRT-PCR and RT-PCR analyses. Bar represents mean (3 replicates) ± standard deviation. ck, standard physiological Cu (0.2 mM), Mn (0.5 mM), Zn (0.5 mM), and Fe (0.1 mM). (a) Expression of COPTs was induced at 3 weeks after deficiency of Cu, Mn, Zn or Fe. -Cu, -Mn, -Zn, or -Fe, deficiency of Cu, Mn, Zn, or Fe. (b) Expression of COPTs was suppressed by overdose of Cu.