Breeding trends on blue honeysuckle (Lonicera caerulea L.)

Blue honeysuckle, also named as haskap or honeyberry, an emerging fruit worldwide, with the species being Lonicera L., originating from the north hemisphere, exhibits high genetic heterogeneity and abundant genetic variation in fruit and leaf traits. However, there are few papers on the research progress of blue honeysuckle breeding and cultivars. The International Union for the Protection of New Varieties of Plants (UPOV) is an effective plant variety protection system, and blue honeysuckle cultivars from different countries and regions are registered in the UPOV database. In this review, we summarized the origin, domestication and germplasm collection, breeding categories and supporting techniques of blue honeysuckle, and the information on registered blue honeysuckle cultivars was analysed based on the UPOV database. Finally, the paper put forward the challenges of blue honeysuckle in development, breeding direction and perspectives to promote the development of blue honeysuckle.