The use of TDZ for the efficient in vitro regeneration and organogenesis of strawberry and blueberry cultivars

Application of in vitro plant biotechnology in berry crops depends on the availability of efficient regeneration protocols that are specific to the genotype background and to the correct combination of exogenous hormones (auxin and cytokinin) added to the medium. Strawberry regeneration protocols are available for different cultivars, while more limited information are available for blueberry cultivars. In this study, we show that the best regeneration efficiency for the leaves of strawberry cultivar Calypso were obtained culturing in a medium supplemented with thidiazuron (TDZ) 0.5 mg L-1 and 2,4-dichlorophenoxyacetic acid (2,4-D) 0.02 mg L-1. The best regeneration efficiency for cultivar Sveva leaves was obtained culturing in a medium supplemented with N6-benzyladenine (BA) 3 mg L-1 and indole-3-butyric acid (IBA) 0.2 mg L-1. In blueberry cultivar Duke, shoot proliferation trials were carried out comparing the effects of 2-isopentenyladenine (2iP) and TDZ; furthermore, experiments of blueberry direct and indirect organogenesis were made, using TDZ as alternatives to zeatin, the most common and expensive hormone used for blueberry in vitro regeneration. Different regeneration responses were observed by using TDZ alone or combined with 2iP. The addition of both 0.2 mg L-1 or 0.5 mg L-1 of TDZ in the medium led to improved callus formation. The addition of 15 mg L-1 of 2iP in the same medium promoted blueberry stem elongation, while inhibiting callus growth. Zeatin was most efficient in direct regeneration of shoots while 0.5 mg L-1 TDZ induced a highest number of shoots by indirect organogenesis. (C) 2016 Elsevier B.V. All rights reserved.