Histochemical localization of GUS expression patterns of pβC1 (A-E) and pβC1-214 (F-J) in transgenic N . tabacum plants. (A, I) Transverse sections of stem, (B, G) underside of the leaf, (C, H) transverse sections through the leaves, (D, J) longitudinal sections of the roots, and (E, F) root. Abbreviations: rc. root cap; vc. vascular cylinder; x. xylem; ph. phloem; ep. external phloem; ip. internal phloem; v. vein; pm. palisade mesophyll; sm. spongy mesophyll; vb. vascular bundle. Scale bars, 20 μm.