Bimolecular fluorescence complementation (BiFC) assay
Coding sequence of ApNMV 1a and MdBT2 were inserted into 35S::SPYCE-cYFP and 35S::SPYNE-nYFP vectors (Walter et al., 2004), respectively. The constructs were transformed into Agrobacterium LBA4404 and co-infiltrated into N. benthamiana leaves. YFP (yellow fluorescent protein) signals were observed under a confocal microscope (Zeiss, LSM880) two days post-infiltration. Different signals were obtained under the “best signal” mode, and images were acquired through single optical sections in the “Frame” mode, with a scan speed of 6 (the scan time was about 10 s).