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- Title
An improved system for the in vitro regeneration of Thapsia garganica via direct organogenesis influence of auxins and cytokinins.
- Authors
Nokwanda P. Makunga; Anna K. Jger; Johannes van Staden
- Abstract
Abstract An improved protocol for mass multiplication directly from leaf material of Thapsia garganicawas developed. Using factorial experimentation, auxins (NAA, IAA, 2,4-D) and cytokinin (BA, kinetin) combinations at 02mgl-1 added to Murashige and Skoog (MS) medium with 30gl-1 sucrose and 8gl-1 agar (pH5.8) were tested for their effect on direct regeneration on leaflet and petiole explants. Of the media tested, the 0.5:1.5 NAA:BA medium was comparable for direct shoot organogenesis to the 2mgl-1 kinetin supplemented medium. However, when shoots were multiplied on these media, the 2mgl-1 kinetin without auxins was most effective as it kept the percentage of callus-derived plantlets to 3% and the number of hyperhydric shoots were minimal at a frequency of 2% compared to 25% on the 0.5:1.5 NAA:BA medium. The 2mgl-1 kinetin medium induced adventitious bud formation in 36% of the explants after 30days. When the cultures were transferred to the same medium for multiplication, an average of six shoots (4.3cm) were derived from each shoot base. Other combinations resulted in callus formation that either preceded shoot production or occurred together with adventitious shoot induction; whereas the 2mgl-1 medium resulted solely in adventitious buds that readily converted and elongated to shoots. On the 0.5:1.5 NAA:BA medium which tended to induce hyperhydric shoots in culture, agar (0.8, [w/v]) (15% hyperhydric plantlets) was more useful in maintaining a high health status in regenerating plantlets than gellan gum (Gelrite; 0.25, [w/v]) (60% hyperhydric plantlets). Although rooting in vitro was difficult, 58% of the propagules were successfully acclimatized when plants were exposed to fungicidal solutions as pre- and post-acclimatization treatments. A comprehensive protocol that allows for a reduction in mortality due to damping-off diseases during ex vitro transplantation of the in vitro-derived T. garganica plantlets is reported. The acclimatization procedure presented here is potentially suited to other umbelliferous species where fungal rots hamper ex vitro establishment.
- Subjects
ACCLIMATIZATION (Plants); AUXIN; ALGAE; CALLUS; BUDWOOD
- Publication
Plant Cell, Tissue & Organ Culture, 2005, Vol 82, Issue 3, p271
- ISSN
0167-6857
- Publication type
Article
- DOI
10.1007/s11240-005-1372-x