Analysis of the AtSEOa and GmSEO-F1 promoter in transgenic plant tissue. CLSM detection of GFPER activity in PAtSEOa-GFPER transgenic A. thaliana plants (A to D) and PGmSEO-F1-GFPER transgenic G. max roots (E, F). (A) Transverse sections through an A. thaliana stem showing GFPER restricted to the phloem. (B) Overlay of fluorescent and transmitted light images of a longitudinal A. thaliana stem section showing GFPER fluorescence in sieve elements (arrows). Non-fluorescent companion cells are marked with an asterisk. (C) Sieve plate of two end-to-end connected fluorescent sieve elements stained with aniline-blue. (D) Sieve element containing large vacuoles, indicated by the white arrow. (E) Longitudinal section through the vascular cylinder of a transgenic G. max root. (F) Sieve element with aniline-blue stained sieve plate. Scale bar = 100 μm in A and E, and 5 μm in B-D and F.