Organogenic Nodule Formation in Hop: A Tool to Study Morphogenesis in Plants with Biotechnological and Medicinal Applications

Figure 1

(a)–(e) Histological and ultrastructural features during organogenic nodule formation and plantlet regeneration from internodal explants cultured on Murashige and Skoog medium (Murashige and Skoog [22]) supplemented with 2 mg/L benzylaminopurine and 0.05 mg/L indole-3-acetic acid. (a) Bright field image of a cross-section of an internode after 15 days in culture showing divisions in cambial and cortical cells. The material was previously embedded in resin. (b) Nodule arising after 28 days in culture and showing a vascular center surrounded by a cortical parenchyma area. (c) Section showing prenodular and nodular structures arising from a single internode after 28 days in culture. Material was previously embedded in paraffin wax. (d) Bright field image showing plantlet regeneration from nodules and separation of polycenter nodules into “daughter nodules.” Arrows point to vascular connections established between vascular bundles of nodule and growing plantlet. Material was previously embedded in paraffin wax. (e) Scanning Electron Microscopy imaging showing multiple shoot bud regeneration from an organogenic nodule. Bar in (a) = 100 𝜇m; bar in (b) = 50 𝜇m; bars in (c) and (e) = 200 𝜇m; bar in (d) = 300 𝜇m. cb: cambial cells, ct: cortical cells, n: nodule, pn: prenodule, sb: shoot bud, s-, vc: vascular center. (c,d,e) were reproduced from [8].