To further confirm the interactions between MaERF9 and -11 and MaACO1 observed in the Y2H assay, this study performed a BiFC assay in tobacco BY-2 protoplasts. MaERF9 or MaERF11 tagged with pSPYNE (split YFP N-terminal fragment expression) and MaACO1 tagged with pSPYCE (split YFP C-terminal fragment expression) were transiently co-expressed in tobacco BY-2 protoplasts following PEG transfection. A robust YFP fluorescent signal was detected in the nucleus of BY-2 cells which expressed MaERF9-pSPYNE or MaERF11-pSPYNE and MaACO1-pSPYCE (Fig. 7). No YFP fluorescent signal was observed either in the cells which expressed MaERF9 or -11-pSPYNE with only the pSPYCE or in those expressed MaACO1-pSPYCE with only the pSPYNE (Fig. 7). Similar results were also observed when MaERF9/MaERF11-pSPYCE were co-transfected with MaACO1-pSPYNE (Fig. 7). These results of Y2H and BiFC assays not only demonstrate in vitro and in vivo interactions between MaERF9 and -11 and MaACO1, but also the specific localization of the interacting proteins in the nucleus.