Auxin and zinc are involved in callus and root formation in rice. However, details of the mechanism underlying this process and functional relation between zinc and auxin are unclear. In this study, proteins induced by auxin and zinc in rice were analyzed by a proteomic approach. Root formation on rice seedlings was promoted by 0.45 microM 2,4-D treatment and was further promoted by addition of 260 microM Zn. Microscopic observation revealed that the number of root primodia formed was significantly increased in 2,4-D- and Zn-treated seedlings than that of the control. A total of seven proteins, as analyzed by 2D-PAGE, were increased, and one protein was decreased by 2,4-D and Zn treatment. Expression of elongation factor-1beta' (EF-1beta') both at transcriptional and translational levels was particular abundant in callus and basal parts of young seedlings, and the accumulation of EF-1beta' was consistent with root formation induced by 2,4-D and Zn. Results indicate that higher level of EF-1beta' expression is necessary for auxin- and zinc-induced root formation in rice.