The technological approaches and practical exploration of cultivar improvement in Chinese jujube

摘要

Chinese jujube [Ziziphus jujuba Mill.) is the most popular cultivated species of the genus Ziziphus. It ranks the number one dry fruit tree in China with a growing area of 2 million ha and annual production of around 6 million t. It is a native of Chinaand has been introduced into approximately 40 countries throughout the world. Some 1,000 cultivars have been released and recorded during its cultivation history of over 7,000 years. Most breeding practices of Chinese jujube are concentrated in China inconsistent with its main commercial production region. The strain selection of Chinese jujube from its wild ancestor sour jujube [Z. acidojujuba Cheng et Liu) could be traced back to 2,600 years ago. Nowadays, the breeding approaches of Chinese jujube include selection breeding, cross breeding, marker assisted selection (MAS) breeding, ploidy breeding, and genetic engineering breeding. Up to now, more than two third of the newly released new cultivars are selected from natural bud mutation or natural seedlings. Polyploid breeding has achieved great success in Chinese jujube and 23 polyploid strains have been obtained and one of them namely 'Chenguang' has been released as the first tetraploid cultivar of Chinese jujube. By the aid of overcoming the twobottlenecks, i.e., serious embryo abortion and difficulty in emasculation, cross breeding was kicked into high gear in the past decade. The genetic engineering breeding was also put into practice recently. The MAS breeding and genetic engineering breeding will be greatly accelerated with the accomplishment of genome sequencing of Chinese jujube very recently.