Efficient Somatic Embryogenesis and Organogenesis of Self-Pollination <i>Artemisia annua</i> Progeny and Artemisinin Formation in Regenerated Plants

Abstract

To enhance the understanding of artemisinin biosynthesis, we have successfully bred self-pollination Artemisia annua plants. Here, we report efficient somatic embryogenesis and organogenesis of self-pollination plants and artemisinin formation in regenerated plants. The first through sixth nodal leaves of seedlings are used as explants. On agar-solidified MS basal medium supplemented with TDZ (0.6 mg/l) and IBA (0.1 mg/l), all explants after inoculation of less than 3 weeks start to form embryogenic calli, which further produce globular, torpedo, heart and early cotyledon embryos. In all six positional leaves, explants from the sixth leaf show the rapidest responses to induction of embryogenic calli and somatic embryos. On this medium, somatic embryos continuously develop into adventitious buds, which can form adventitious roots on a rooting medium containing NAA (0.5 mg/l). Meanwhile, on agar-solidified MS basal medium supplemented with BAP (1 mg/l) and NAA (0.05 mg/l), approximately 100% of explants from leaves #3 - 6 form calli in less than 3 weeks of inoculation and adventitious buds via organogenesis in 3 - 4 weeks. In all six positional leaves, explants from the sixth leaf exhibit the rapidest response to induction of calli and adventitious buds. Nearly 100% adventitious buds can form adventitious roots on the rooting medium. Regenerated plants from both somatic embryogenesis and organogenesis complete self-pollination to produce seeds in 80 - 90 days of growth in growth chamber. LC-ESI-MS analysis demonstrates that regenerated plants biosynthesize artemisinin. These results show the highly efficient regeneration capacity of self-pollination A. annua plants that can form a new platform to enhance the understanding of artemisinin biosynthesis and metabolic engineering.