Expression of the OS-ACS5 gene during development. Representation of longitudinal (A, C, H, and L) and transverse sections of different tissues of transgenic line pRG11-2, as well as a transverse stem section of the control line pRG16-73 (Q). A through G, J, K, M, and N are bright-field images, in which the blue color represents GUS activity, whereas H, I, L, and O–Q are dark-field images, in which GUS appears purple. A, Scutellum; B, coleoptile node; C, scutellum, mesocotyl, and coleoptile node; D, coleoptile and its two vascular bundles; E, leaf sheath; F, stem above node 6 (the highest internode); G, stem above node 4; H, young stem; I, detailed view of stem vascular bundle; J, vascular bundles in mature leaf sheath; K, sheath of leaf 4; L, initiation of tiller; M, stem; N, developing vascular bundles in a young leaf sheath; O, stem vascular bundles; P, node 6. Plant age: 4 d (A–D), 9 d (E), and 8 weeks (F–Q). AN, Anastomosis; AR, adventitious root; BS, bundle sheath cell layer; CN, coleoptile node; E, epithelium; IN, imperfect leaf node; LV, longitudinally orientated vascular bundle in node; M, mesocotyl; N6 and N7, sixth and seventh node, respectively; PA, parenchyma; S, stem; SC, scutellum; SH, leaf sheath; TL, tiller; VB, vascular bundles; VS, vascular system.