Effects of Growth Regulators, Media and Explant Types on Microtuberization of Potato Ayten Kubra Yagiz 1 & Caner Yavuz 1 & Cehibe Tarim 1 & Ufuk Demirel 1 & Mehmet Emin Caliskan 1 Accepted: 7 September 2020 # The Potato Association of America 2020 Abstract Microtubers (MT) are an innovative approach for nuclear seed production in potato (Solanum tuberosum L.). They are produced under in vitro conditions using different protocols. However, content and type of growth media as well as explant types significantly affect the MT production efficiency. This study was conducted to develop an efficient protocol for MT production by evaluating different growth regulators at different concentrations, types of growth media and explants in two separate experiments. In Experiment 1, the effects of six different growth regulators, and their three application rates on MT formation were compared. The effects of two growth media and three explant types on MT production were compared in Experiment 2. As a result, our studies indicated that cotton based liquid MS medium containing 0.1 mg L -1 Thidiazuron, and using whole plants as explant can be used for efficient MT production in potato. Resumen Los microtubérculos (MT) son un enfoque innovador para la producción de semilla nuclear en papa (Solanum tuberosum L.). Se producen bajo condiciones in vitro usando diferentes protocolos. No obstante, el contenido y tipo de medio de cultivo, así como los tipos de explantes, afectan significativamente la eficiencia en la producción de microtubérculo. Este estudio se condujo para desarrollar un protocolo eficiente para la producción de MT mediante la evaluación de diferentes reguladores de crecimiento a diferentes concentraciones, tipo de medios de cultivo y explantes en dos experimentos separados. En el experimento 1, se compararon los efectos de seis diferentes reguladores de crecimiento y sus tres niveles de aplicación en la formación de MT. En el experimento 2, se compararon los efectos de dos medios de crecimiento y tres tipos de explante en la producción de microtubérculos. Como resultado, nuestros estudios indicaron que el medio líquido MS con base de algodón con 0.1 mg L-1 de thidiazurón, y usando plantas completas como explante puede usarse para la producción eficiente de microtubérculo en papa. Keywords Solanum tuberosum . Nuclear seed . Growth regulators . In vitro . Tissue culture Potato is one of the most important food crops grown worldwide with annual global production of over 388 millions tonnes (Anonymous 2019). It is commercially propagated vegetatively using seed tubers, which makes potato very vulnerable to infection and transmission of seed borne diseases (Ranalli et al. 1994; Gopal et al. 1997). Therefore, use of disease free seed tubers is one of the key points for successful potato production. Certified seed production systems generally start with minitubers produced from disease-free in vitro plants un- der controlled (i.e. greenhouse) conditions (Struik 2007; van Loon 2007). Low multiplication rates and adaptation problems of in vitro plants after transplanting to in vivo conditions for minitubers production are the main con- straints of minitubers-based seed potato production systems. Microtubers (or in vitro tubers) (MT) are miniature seed potatoes weighing 24 to 273 mg, and can be considered as the intermediate stage between in vitro plantlets and minitubers (Ranalli 2007). Although microtuberization was defined first by Barker in 1953, the potential use of MT was then underestimated (Barker 1953). MT produc- tion is conducted under controlled environment, so infec- tion risk is considered to be very low, which makes MT an ideal starting material for seed tuber production. Hence, * Ayten Kubra Yagiz aytenkubraturkmen@gmail.com 1 Agricultural Genetic Engineering Department, Faculty of Agricultural Sciences and Technologies, Niğde Omer Halisdemir University, Niğde, Turkey American Journal of Potato Research https://doi.org/10.1007/s12230-020-09801-4