Plant Regeneration through Protocorm-like Bodies Induced from Leaf and Petiole Explants of Pinellia ternata, an Important Medicinal Plant

Pinellia ternata (Thunb.) Breit. is an important herb of traditional Chinese medicine, and Jing Pinellia, a landrace of south central Hubei Province, China, is particularly popular due to its renowned high-quality tubers. Pinellic acid from the tuber has been identified to be an effective oral adjuvant for nasal influenza vaccine. Current production of pinellia relies mainly on the tuber, which significantly limits its production. The objective of this study was to establish protocols for efficient regeneration of plantlets as liners for commercial production. Leaf and petiole explants were cultured on Murashige and Skoog (MS) basal medium supplemented with 2.22, 4.44, and 8.88 μM 6-benzyladenine (BA) and 0.54, 1.07, and 2.69 μM α-naphthalene acetic acid (NAA) in a factorial design. Protocorm-like bodies directly appeared from leaf explants 30 days after inoculation. Petiole explants first produced calluses and then protocorm-like bodies 40 days from the initial culture. MS medium with 2.22 μM BA and 1.07 μM NAA resulted in 100% of leaf and petiole explants producing protocorm-like bodies, up to 11 and 8.59 per explant, respectively. The mean diameters of the protocorm-like bodies derived from leaf and petiole explants were 0.27 and 0.2 cm, respectively. All protocorm-like bodies produced adventitious shoots and roots with shoot height ranging from 1.79 to 2.79 cm and root length of 1.77 to 2.39 cm. The regenerated plantlets were morphologically stable and grew vigorously in cell plug trays filled with a soilless substrate in a shaded greenhouse. The liners were healthy and readily available for commercial production.