Establishment of a regeneration system for ‘Minihyang,’ a domestic citrus variety with high utility as a genetic resource

Abstract

Abstract Background Citrus ‘Minihyang’ is a novel citrus cultivar created through the hybridization of Citrus kinokuni and Citrus poonensis. This domestic cultivar has a small fruit size and high sugar content, making it highly valuable in the niche market both for ornamental and commercial purposes. Additionally, as a genetic resource, ‘Minihyang’ is highly valuable. However, the lack of a tissue culture system for ‘Minihyang’ could potentially constrain the utilization of bioengineering techniques for its cultivation. Therefore, in this study, we aimed to develop a regeneration system for ‘Minihyang’ using cultured cells of unfertilized and undeveloped seeds in mature fruits.Results Somatic embryogenic cells were obtained on somatic embryogenesis induction modified Murashige and Tucker (SIME) medium, and the propagated cells were obtained through subculture at 4-week intervals in a modified Murashige and Skoog (EMS) medium. Rather than normal cotyledon-stage embryos, abnormal globular embryos were observed after 4 weeks of culture in an EMS medium containing 70 g·L− 1 lactose and 16 g·L− 1 agar. Through the regeneration of plants from these abnormal globular embryos, somatic embryos with developing shoots and roots were obtained within 3 weeks of culture in an EMS medium containing 0.05 M sorbitol and 0.05 M galactose as carbohydrate sources, 0.5 mg·L− 1 GA3, and 2 g·L− 1 gelrite. These embryos were transferred to and cultured in a basic MS medium enriched with 500 mg·L− 1 malt extract, 50 g·L− 1 sucrose, and 8 g·L− 1 agar to produce normal plants.Conclusions ‘Minihyang’ can serve as a promising genetic resource for developing bioactive cultivars using biotechnological techniques and can be used to breed cultivars that can be consumed whole.