In Vitro Cultivation of Purple-Fleshed Potato Varieties: Insights into Their Growth and Development

Purple-fleshed potatoes (PFP) are varieties of <i>Solanum tuberosum</i> L., which recently have been recorded to be more and more cultivated and consumed in all European countries, including Romania, as they are promoted for their content in bioactive compounds and benefits to human health. This paper presents a micropropagation protocol study for PFP varieties already traded into the Romanian market, namely Blue Danube (BD), Salad Blue (SB), Violet Negretin (VN), and Violet Queen (VQ). These varieties were tested for in vitro micropropagation also considering asepsis, initiation, callus formation, and microtuberization. To establish the optimum asepsis treatment, a preliminary experiment was performed and, the best results were obtained by using 70% EtOH (1 min) followed by 20% (<i>v</i>/<i>v</i>) Domestos^® (20 min). The MS formula (Murashige and Skoog 1962) was tested as the basic culture medium without growth regulators for all tested stages except for callus initiation and its further multiplication stages. The effect of glycine on direct organogenesis and shoot multiplication was evaluated for propagated micro-cuttings. We emphasize that the addition of glycine at a concentration of 15 mg/L to the culture medium induced a better plantlet vigor for all four varieties. Regarding the indirect organogenesis, culture medium supplemented with NAA (5.00 mg/L), GA₃ (1.00 mg/L), TDZ (1.00 mg/L) and glycine (15.00 mg/L) induced the best results for shoot cluster regeneration as well as turning of white callus from control to purple callus. Further, the microtuberization was successfully produced when sucrose was supplemented at 8% (<i>w</i>/<i>v</i>) into the culture medium. Among all four tested PFP varieties, SB has proven to give the best results regarding the adaptability for in vitro cultivation.