Influence of Cytokinins, Dark Incubation and Air-Lift Bioreactor Culture on Axillary Shoot Proliferation of Al-Taif Rose (Rosa damascena trigintipetala (Diek) R. Keller)

Abstract

Rose is a widely favored floriculture crop that is commercially propagated through the application of tissue culture techniques. Here, we report an effective method for axillary shoot proliferation in Al-Taif rose, an important cultivar for rose oil industry. Stem nodes were excised from an adult donor Al-Taif rose shrub and cultured for 4 weeks on Murashige and Skoog’s (MS) medium supplemented with 6-benzylaminopurine (BAP) or gibberellic acid (GA3) at 0 and 3 mg·L−1 to induce the sprouting of axillary shoots. Al-Taif rose shoots were cultured in vitro for 6 weeks on MS medium fortified with different concentrations of cytokinins, light/dark incubation and different culture types (gelled and liquid/bioreactor culture). The culture conditions that were applied had a noteworthy impact on the responses of Al-Taif rose shoot proliferation. The supplementation of the medium with 6-benzylaminopurine (BAP) resulted in an augmented rate of shoot proliferation in comparison to other cytokinins. Additionally, dark incubation limited foliage growth, leaf yellowing and abscission and favored shoot proliferation compared with light incubation. Liquid culture using bioreactors provided higher axillary shoot proliferation and growth as compared with gelled culture. A continuous immersion system with a net provided the highest axillary shoots (four shoots per explant) and shoot length (16.5 cm), whereas an immersion system without a net provided the highest fresh weight of axillary shoots (499 mg per explant). These findings will improve commercial propagation and contribute to the rose oil industry of Al-Taif rose.