Callus induction and in vitro plant regeneration of Primula denticulata subsp. sinodenticulata

Primula denticulata subsp. sinodenticulata is an endemic medicinal plant from China; however, its resources are extremely scarce due to a lot of obstacles such as scattered distribution, long natural renewal cycle, and overexploitation for medicinal value. In this study, a rapid propagation protocol in vitro of P. denticulata subsp. sinodenticulata was established, hoping to provide a possible way for resource protection. The leaves and petioles of different ages of the plant were selected as explants, and Murashige and Skoog (MS) medium were used as the basic medium. The appropriate types and concentrations of hormones for growth were selected via a single factor, and then the effects of types and concentrations of different hormones on callus induction and cluster bud occurrence were investigated by a complete combination experiment. The study showed that the callus with a strong redifferentiation capacity was obtained from 8-to 10-day old leaves and 10-to 20-day old petioles in MS medium with 0.5 mg/l 6-benzylaminopurine (BA) and 1.0 mg/l ??-naphthaleneacetic acid (NAA) after 30 to 40 days of culture. Subsequently, green cluster bud started to appear with 100% occurrence rate. The obtained cluster bud was subcultured in the aforementioned medium with 12.67 proliferation coefficient. The optimal rooting medium was the hormone-free 1/2 MS medium; the rooting rate was 100%, and the survival rate was over 95%. In this study, micropropagation of P. denticulata subsp. sinodenticulata was established, which can provide an optional method for the protection of wild resources.