GFP fluorescence localization in RolC-SUT-GFP fusion. GFP fluorescence was detected on longitudinal hand sections of tobacco transgenic petiole under CLSM and co-stained with DAPI and aniline blue. In both cases, GFP fluorescence is localized to companion cells. A) All constructs were prepared in a modified pGPTV-HPT under the control of the CC-specific, RolC, promoter. The asterisk indicates the position of the start codon. T, nos terminator. B) RolC-LeSUT1-GFP petiole, C) RolC-LeSUT1-GFP-3'-UTR petiole. D) Untransformed wild type tobacco leaf petiole visualized with the average PMT level used for the above images CC, companion cell; SE, sieve element; sp, sieve plate; n, nucleus. Bar equals to 10 μm.