In vitro regeneration of Phaseolus vulgaris L. via direct and indirect organogenesis

A stable and efficient regeneration system is a necessary condition for the genetic transformation of Phaseolus vulgaris L. In this study, cotyledonary nodes with one cotyledon, cotyledonary nodes with two cotyledons, embryonic axes and root segments of 5-day-old germinated seeds were used as explants to evaluate explants to induce shoots and calli. Besides, using cotyledonary nodes with one cotyledon as explants, the effects of different concentrations of auxins and cytokinins on the direct and indirect organogenesis of common bean were investigated. As a result, embryonic axes and cotyledonary nodes with two cotyledons were the most effective explant types for the formation of shoots and calli. The cotyledonary nodes with one cotyledon were cultured in the shoot induction medium containing 7 mg L-1 6-benzyladenine (BAP) and 0.2 mg L-1 alpha-naphthaleneacetic acid (NAA). 74.21% of explants directly formed shoots and average number of shoots was up to 2.91. On the rooting medium supplemented with 0.5 mg L-1 indole-3-butyric acid (IBA), the rooting rate of shoots reached 100% and the number of main roots formed was the most. The addition of 0.5 mg L-1 thidiazuron (TDZ) was optimum for callus induction, and the induction rate could reach 91.51%. The shoot regeneration frequency was 93.33% when calli subcultured on the shoot induction medium supplemented with 1.0 mg L-1 BAP. Average 4.27 shoots were produced by per callus and rooted on the shoot induction medium. This report descripts an efficient common bean regeneration system through direct and indirect organogenesis, which can provide reference for its subsequent genetic transformation research.