High-frequency Microtuberization by One-step Culture without Medium Renewal from Leaf Explants of Pinellia ternata, a Medicinal Plant

Abstract

Pinellia ternata is an important medicinal herb in Northeast Asia, but its propagation rate is quite low in nature. This study was performed to develop a simple and rapid micropropagation method for applying to a plant factory system. In the regeneration process for the sustainable production of in vitro leaf explants, callus induction and propagation from leaf explants of P. ternata were excellent in MS medium containing 2.0 mg·L -1 2,4-D and 0.2 mg·L -1 BA. The highest number of shoots (8.8 per callus) was regenerated from calluses cultured on a medium containing 2.0 mg·L -1 NAA and 0.2 mg·L -1 KIN. The callus proliferation with subsequent plant regeneration was achieved at the same time in regeneration medium, and the year-round production of in vitro leaf explants was possible in the regeneration cycle. The direct microtuberization from in vitro whole leaf explants was also achieved through the one-step culture without medium renewal. The highest frequency of microtuber formation (93.0%) as well as the highest number of microtubers per explant (6.1) was observed by one-step culture in MS medium containing 2.0 mg·L -1 NAA and 0.2 mg·L -1 BA. Thus, the direct microtuberization from in vitro leaf explants was successfully achieved by the one-step culture protocol without medium renewal from microtuber induction to harvest. The adequately dried microtubers were well grown like an artificial seed in the pot culture containing a commercial soil. Accordingly, the in vitro microtubers through one-step culture could be commercially used as seed tubers for a plant factory system. Additional key words: callus induction, growth regulators, plant regeneration, seed tubers, soil cultivation