Protoplast technology in ornamental plants: Current progress and potential applications on genetic improvement

The international floriculture industry is expected to become bigger in the near future, owing to the continuous increase in the demand for ornamental plants. To facilitate the demand, many efforts are being paid to produce new cultivars with superior floral traits, such as novel color patterns and shapes and improved flower longevity. Protoplasts have been used to produce new cultivars, especially commercially important ornamental plants with incompatibility barriers in sexual hybridization, using protoplast fusion and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated genome editing. However, the success of the protoplast isolation to shoot regeneration process remains a bottleneck for most ornamental plants. In this review, we highlighted the role of the factors that affect the protoplast isolation to shoot regeneration process of ornamental plants. The practical application of protoplasts in developing new genetically improved cultivars from some ornamental plants via somatic hybridization and genome editing was also described. Information in this review will contribute to the success of plant regeneration from protoplasts for ornamental plants and provide insights on new cultivar production, mainly from commercially important ornamental plants that cannot produce a new cultivar via sexual breeding.