Optimizing the concentrations of plant growth regulators for in vitro shoot cultures, callus induction and shoot regeneration from calluses of grapes

Abstract

Aim: To optimize the concentrations of growth regulators in the media for the proficient micropropagation of grapevine (Vitis vinifera L.) cv. King's Ruby. Methods and results: Apical meristems of the cultivar were used to establish in vitro shoot cultures. Nodal explants from these shoots were inoculated in half strength Murashige and Skoog (MS) shoot proliferation media supplemented with benzyl aminopurine (BAP), kinetin, glycine and gibberellic acid (GA3). A higher number of shoots (5.33) with greater length (2.75 cm) was produced in the medium supplemented with 1.0 mg L-1 BAP and 0.1 mg L-1 GA3. Callus induction from leaf explants taken from in vitro grown shoots was greater (73.00%) on the medium containing 2.0 mg-12,4-dichlorophenoxyacetic acid (2,4-D), 0.3 mg L-1 BAP and 0.2 mg L-1 α-naphthaleneacetic acid (NAA). The maximum shoot regeneration frequency (53.33%) was achieved on the medium supplemented with 1.5 mg L-1 BAP and 0.5 mg L-1 NAA, and the rooting of regenerated shoots was successful on growth regulator-free half strength MS medium. Conclusion: Optimizing the BAP and GA3 and omitting the glycine and kinetin in the culture medium increased the number and length of shoots. We recommended to use higher 2,4-D and lower BAP concentrations in the medium for callus induction of the leaf explants taken from in vitro grown shoots, and relatively high levels of BAP and NAA (1.5 and 0.5 mg L-1, respectively) for maximum shoot regeneration. Finally, we suggest the half strength growth regulators-free MS medium for the rooting of regenerated shoots. Significance and impact of the study: Optimizing the concentration of growth regulators is crucial to establish in vitro shoot cultures, induce calluses, regenerate shoot and, hence, to propagate disease-free true to type grape cultivars in a short time.