Micropropagation and DNA delivery studies in onion cultivars of Bellary, CO3

Abstract

Onion is one of the most important vegetables grown all over the world. In the present study, rapidly growing and maintainable callus was accomplished using the basal meristem plate and twin scale leaves as explants in Bellary and CO3 varieties for callus induction and in vitro bulb formation. The two cultivars were transformed with Agrobacterium tumefaciens EHA 105 harboring the binary vector pCAMBIA 1301 containing the GUS gene with different concentrations of acetosyringone. The outcome of this study revealed that the frequency of callus induction was maximum on Murashige and Skoog medium (MS) fortified with B5 vitamins supplemented with 0.5 and 1 mg L−1 picloram. Regeneration of plantlets from the callus was observed on MS supplemented with 0.5 mg L−1 each of BAP and KIN and 0.1 mg L−1 NAA. In vitro bulb response was observed on MS with B5 vitamins supplemented with 2.0 mg L−1 BAP. GUS gene integration in the transgenic plants was confirmed by PCR. The maximum GUS gene expression was observed at a concentration of 150 µM acetosyringone in the transformed plants by histochemical assay. This protocol allows effective genetic transformation and regeneration system of onion via in vitro bulb development.