Development of Haploid Plants by Shed-Microspore Culture in Platycodon grandiflorum (Jacq.) A. DC

Anther and microspore cultures are efficient methods for inducing haploids in plants. The microspore culture by chromosome-doubling method can produce double haploid lines, developing pure lines within the first or second generations. This study aimed to induce haploid plants in Platycodon grandiflorum using the shed-microspore culture method. P. grandiflorum floral buds (n = 1503) were cultured in six types of medium to induce haploids. Anthers were placed on a solid-liquid double-layer medium and cold pre-treated at 9 °C for one week, followed by incubation in the dark at 25 °C. Embryogenesis was observed after approximately 70 days of culture, producing haploid plants through regeneration. Of the 1503 floral buds, embryos developed in 120 buds, resulting in the induction of 402 individuals. Among the media used, Schenk and Hildebrandt (SH) and 1/2SH exhibited high efficiency, with embryogenesis ratios of 12% and 13.4%, respectively. Additionally, the highest embryogenesis ratio (15.3%) was observed in flower buds sized 10 mm or less. Therefore, we established shed-microspore culture conditions to induce haploids in P. grandiflorum. Using this method, haploids can be efficiently induced in P. grandiflorum, shortening the breeding period by enabling the rapid development of inbred lines.