Auxin and Cytokinin-Mediated Regeneration of Whole Paulownia tomentosa Propagules via Axillary Shoot Multiplication and Root Organogenesis

Paulownia tomentosa is a short rotation, fast growing multipurpose tree recently introduced to Egypt. Demand of local market for planting material necessitated the use of plant tissue culture technology. In this study, lateral buds of stem nodal segments were induced to multiply and develop into axillary shootlets on a shoot inducing media under the action and interaction of benzyl adenine, kinetin and thidiazuron in various factorial concentrations and then the separated shootlets (micro shoots) were rooted using different levels of Indole-3-acetic acid, α-naphthalene acetic acid and Indole butyric acid alone and/or combined using MS as a culture media (root inducing media). Results have revealed in many cases that the used cytokinins synergized each other and in other cases antagonized each other in shoot morphogenesis. The same was also observed with auxins on root organogenesis in vitro. The best shootlets per explant number was obtained using BA at 0.5 mg/l + Kin at 0.75 mg/l and reached up to 14.0 shootlet per explant which was a significant value in comparison to the corresponding control (4.33), whereas the lowest shootlet number (3.33) was reported with Kin at 0.75 mg/l + TDZ at 0.75 mg/l within 6 weeks. The separated shoots developed roots within 6 weeks and the best root fresh weight reached up 0.92 g using 0.3 IAA + 0.5 NAA, a result that is statistically significant over the corresponding control (0.03). The obtained propagules were then taken out of the culture vessels, washed out and acclimatized successfully in sand and peat moss (1:1 v/v) substrate. Results of the present work may help provide plant material for mass propagation of this plant in Egypt.