Bimolecular fluorescence complementation (BiFC) assay

For constructs used in the BiFC experiment, the N-terminal (pSAT1-N) and C-terminal (pSAT1-C) EYFP vectors were used. The full-length of all PslDELLA, including the mutated PslRGL_.MU and PslRGA_.MU versions were fused into the SacII-BamHI site of the pSAT1-C vector. Consequently, plum GA-receptors PslGID1b and 1c were inserted into the BglII-BamHI of the pSAT1-N vector. The different combinations of constructs encoding NY and CY at similar concentrations were mixed and then co-transfected into protoplasts obtained from suspension-cultured tobacco BY-2 cells in the presence or absence of 100 μM GA₃, as described previously [13]. All assays were repeated at least three times and visualized using confocal microscopy.