Cloning of Reporter Gene Constructs for AtSUC6Col-0 and AtSUC7Col-0

For the pAtSUC6:AtSUC6g-reporter plants a 4,478-bp fragment including the genomic sequence of AtSUC6_Col-0 and 2,547 bp upstream of the start ATG was amplified with the primer pair AtSUC6-2547f+CACC and AtSUC6c+1476r (Supplementary Table 4), cloned into pENTR/D-TOPO (Invitrogen) and inserted upstream of the GUS- or GFP::nos terminator box by LR-reaction in pBASTA-GUS or pBASTA-GFP (Rottmann et al., 2016) yielding plasmids pTR314 and pTR315, respectively. For reporter plants expressing GUS or GFP fusions of AtSUC7_Col-0 under the control of the native promoter a 3,826-bp fragment including 1,896 bp upstream of the start ATG was amplified with primers AtSUC7-1896f+CACC and AtSUC7c+1473r (Supplementary Table 4) and cloned into pENTR/D-TOPO (Invitrogen). The complete pAtSUC7:AtSUC7g sequence was finally cloned into pBASTA-GUS or pBASTA-GFP by LR reaction yielding plasmids pTR3 and pTR4, respectively. For reporter plants expressing GUS without the genomic sequence of AtSUC7 under the control of the AtSUC7_Col-0 promoter the 1,896-bp fragment upstream of the start ATG was amplified with primers AtSUC7-1896f+SbfI and AtSUC7-1r+AscI (Supplementary Table 4) and used to exchange the 35S promoter of the Gateway^® vector pMDC43 (Curtis and Grossniklaus, 2003) in front of the attachment site AttR1 via the added SbfI/AscI sites. The coding sequence for GUS was then inserted via LR reaction from pENTR-GUS (Invitrogen) yielding plasmid pTR95.