The CDSs of ATB''δ (AT5G28900.1) and FASS (AT5G18580.1) were amplified by PCR using primers listed in Supplementary Table S2 and the cDNA sample prepared as described above. The PCR products were digested with KpnI and SpeI, and inserted into the KpnI–SpeI site of pBS-35SMCS-cYFP (Tsugama et al., 2012c (link)), generating pBS-35S-ATB''δ-cYFP and pBS-35S-FASS-cYFP. The CDS of VIP1 was inserted into the pBS-35SMCS-nYFP-2 vector as previously described (Tsugama et al., 2012c (link), 2014 (link)), generating pBS-35S-VIP1-nYFP. Either pBS-35SMCS-nYFP-2 or pBS-35S-VIP1-nYFP (500 ng) was mixed with pBS-35SMCS-cYFP, pBS-35S-ATB''δ-cYFP, or pBS-35S-FASS-cYFP (500 ng), and bound to gold particles. These constructs were co-introduced into onion epidermal cells with the Biolistic PDS-1000/He particle delivery system (Bio-Rad, Hercules, CA, USA). Cells were then incubated for 12 h at room temperature, and BiFC signals were observed using the BX50 epifluorescence microscope (Olympus) equipped with the fluorescence mirror units U-MGFPHQ (Olympus) (for detecting BiFC signals) and an ORCA-ER-1394 digital camera (Hamamatsu Photonics, Hamamatsu, Japan). Images were processed with GIMP and Inkscape.