RESUMO
In this work, plant regeneration via somatic embryogenesis was achieved from leaf and internode derived callus of Wedelia calendulacea, an endangered medicinal plant. Primary callus was induced by culturing leaf disc and internode explant on Murashige and Skoog medium supplemented with 2.0 mg L-1 of 2,4-D under light condition. Transfer of embryogenic callus on a reduced concentration of 2,4-D facilitated somatic embryo development while calluses remained unorganized at the same 2,4-D level. A histological analysis confirmed somatic embryo by revealing the presence of a closed vascular system in the developing embryos and lack of a vascularconnection with surrounding callus tissues. Somatic embryos germinated into plantlets upon transfer on MS medium containing 1.0 mg L-1 BAP plus 0.5 mg L-1 GA3. Plantlets were acclimatized successfully and survived under soil condition. This is the first on somatic embryogenesis of W.calendulacea. This result could facilitate genetic transformation of this important medicinal plant.
RESUMO
The aim of this work was to develop a protocol for rapid micropropagation of an elite F1 hybrid watermelon cultivar using shoot tip of field-grown plants. Maximum frequency (73%) of shoot tip showed growth response in MS medium supplemented with 5 mg l-1 benzyl adenine (BA) and 0.1 mg l-1 indole-3 acetic acid (IAA). Upon transfer to cytokinin-enriched medium, the cultures produced multiple shoots and 2.0 mg l-1 BA was optimum in this respect. Addition of gibberellic acid (GA3) in the multiplication medium resulted in better growth of shoots. Rooting rate was 100% when shoots were obtained from second subculture were cultured in medium with 1.0 mg l-1 indole-3 butyric acid (IBA). The shoots produced more roots with increasing number of subcultures. About 72% of the regenerated plantlets acclimatized successfully and survived in the soil condition.