Assessment of different factors to induce the adventitious regeneration in two blackberry cultivars starting from leaf and petiole explants

A successful adventitious regeneration is considered as a mandatory starting point for the rapid obtainment of genetically improved blackberry cultivars through biotechnological tools. As aim of our work, N6-benzylaminopurine (BAP) and thidiazuron (TDZ), supplemented at a concentration of 3 mg L-1 to the culture medium, were tested for their capacity to induce in vitro shoot organogenesis using whole leaf and petiole of 'Loch Ness' and 'Loch Tay' as different starting explants. We observed that 3 mg L-1 TDZ was more efficient in stimulating adventitious regeneration compared to 3 mg L-1 BAP when both types of explants of 'Loch Ness' and 'Loch Tay' were used. Furthermore, petiole resulted to be the most promising explant as starting tissue with a percentage of regeneration up to 18%. Thus, the effect of 200 mg L-1 cefotaxime and kanamycin (added at different concentrations in the suitable regeneration medium previously tested) on petiole organogenesis was also assessed to be used in future Agrobacterium-mediated genetic transformation experiments on both cultivars. In general, 200 mg L-1 cefotaxime did not show any negative impact on the regeneration percentage from petiole of Loch Tay, and 10 mg L-1 kanamycin resulted to be the most appropriate concentration to select buds from 'Loch Ness' and 'Loch Tay' petioles in future transformation trials. In conclusion, we tested preliminary regeneration strategies (starting from different type of explants) usable for the application of biotechnological approaches for the genetic improvement of blackberry cultivars.