Study on key techniques of polyploid induction in Ziziphus jujuba Mill. cv. ‘Teapot’

Objective In vitro polyploid breeding is an important method for jujube breeding. The study of its key technologies is conducive to the establishment and improvement of polyploid breeding system and the creation of polyploid germplasm of jujube.

Method In this study, the leaves of Ziziphus jujuba Mill. cv. ‘Teapot’ were used as materials, and the leaves of different days (7−20 day) were fixed and then made into paraffin sections for cytological observation. On this basis, the leaf adventitious bud regeneration technology was combined with the colchicine chromosome doubling technique. After the leaves were pre-cultured for 8, 9, 10 and 11 days, they were treated with 70 mg/L and 90 mg/L colchicine for 48 and 72 hours, and the flow cytometry ploidy test was performed on the adventitious buds obtained after treatment.

Result Through the cytological study on the optimal pre-culture time of the leaves, it can be concluded that the meristematic cells have the strongest division ability and no differentiation during the pre-culture of 8−9 days. During this period, treatment of leaves with colchicine can greatly increase the induction rate and effectively avoid the appearance of chimeras and mixoploids. The chromosome doubling test found that after 8 days of pre-culture, the induction rate was up to 4.11% after treatment with 70 mg/L colchicine for 72 hours, and 8 polyploid plants were successfully obtained. It was confirmed by flow cytometry that these 8 polyploids were pure tetraploids.

Conclusion This study explores the technical method of artificially inducing polyploidy of Ziziphus jujuba Mill. cv. ‘Teapot’ by adventitious bud regeneration technology and colchicine chromosome doubling technique.