High frequency in vitro regeneration of Chinese cabbage (Cv. kenshin) from hypocotyl and cotyledon explants

An easy and efficient in vitro regeneration protocol was established for Chinese cabbage, cv. Kenshin (Brassica rapa ssp. pekinensis), using hypocotyl and cotyledon explants. The individual and combined effects of different plant growth regulators were examined in detail at various stages of regeneration through the direct regeneration method. Maximum shoot induction (3.41 shoots/ hypocotyl explant) occurred on Murashige and Skoog medium containing benzyladenine (4 mg·L^-1), naphthalene acetic acid (1 mg·L^-1), and silver nitrate (4 mg·L^-1). These in vitro-regenerated shoots elongated on the same medium and produced abundant roots on half-strength MS medium. Rooted plantlets were successfully hardened and acclimatized with a survival rate of 86%. This optimized method used for cv. Kenshin was studied on two more lines, CNU_11635 and rapid-cycling RCBr cv.R-o-18.Among them, cv. Kenshin was found to be the best responding cultivar with a higher shoot production response of 79%. This method can be applied to regenerate plants after gene transfer and genome editing.