The apical bud as a novel explant for high-frequency in vitro plantlet regeneration of <Emphasis Type="Italic">Perilla frutescens</Emphasis> L. Britton

In this study, we established an in vitro regeneration system to maximize the recovery of leafy perilla (Perilla frutescens L. Britton) plantlets as part of developing a molecular biotechnology-based metabolic engineering program for this crop plant. Hypocotyl segments including the apical buds were used as explants for the direct production of shoots without an interim callus phase. The number of shoots produced from the apical buds peaked within 3–4 weeks, and the shoots were subsequently cultured on Murashige and Skoog (MS) media supplemented with 2 mg l⁻¹ benzylaminopurine (BA). Spontaneous rhizogenesis was observed after 7–10 days of culture on MS media without hormonal additives. The rooted shoots developed into normal plants in soil after hardening on distilled water for 3–4 days. The average plantlet regeneration frequency was higher for the apical buds (64.33%) than for the top (15.66%), middle (4%), and basal (1.33%) segments of the hypocotyls. This regeneration system demonstrates a capacity for high-frequency plantlet recovery and thus should be considered for use in the genetic manipulation of leafy perilla.