Feasible strategies for efficient propagation system of Paeonia lactiflora ‘Hang Baishao’: In vitro culture of embryos

Herbaceous peony (Paeonia lactiflora Pall.) is a renowned traditional Chinese flower, which has been cherished by people since ancient times. It holds significant value as both an agricultural cash crop and an ornamental and medicinal plant. However, the lack of in vitro propagation system has been long hindered the commercial production of this species and the development of new cultivars. In this study, the low chilling requirement cultivar Paeonia lactiflora 'Hang Baishao' that originated from low latitudes of China, was used to study the in vitro culture of embryos. The results of our experiment showed that the optimal medium for in vitro culture of embryos was a 1/2 Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzyladenine (6-BA), 1.0 mg/L gibberellic acid (GA3) and 2.0 g/L polyvinyl pyrrolidone (PVP). Additionally, histological observations revealed the crucial role of vascular bundle development in the survival of transplants. Plants with well-developed vascular tissue exhibited better transplanting success. This study presents, for the first time, a protocol for embryos propagation and transplanting of 'Hang Baishao', a cultivar with low chilling requirement (CR) during winter. This study provides an efficient method for in vitro culture of 'Hang Baishao', and makes it possible for large-scale production, utilization, and germplasm preservation of this species.