Micropropagation of Astragalus holmgreniorum (Holmgren milkvetch), an endemic and endangered species

Astragalus holmgreniorum (Holmgren milkvetch) is a plant of the Fabaceae family endemic to northwestern Arizona and Washington County, Utah. The species is threatened by urban and recreational development and has been listed as endangered. Here we report a protocol for micropropagation of A. holmgreniorum that could provide a system for preservation of this species and for biotechnological applications. The best response for embryo formation and development of shoots from those embryos was obtained with Treatments 4 (1 mg/L BAP, 0 mg/L 2,4-D) and 6 (1 mg/L BAP, 7 mg/L 2,4-D). The response to these treatments is similar for both stem and leaf explants. The best response was observed when the leaf explants were placed with the abaxial side in contact with the media. After 1–3 weeks exposure of the explants to the media with growth regulators, the explants should be moved to media with no growth regulators to initiate the morphogenetic process. To the best of our knowledge, this is the first report of successful micropropagation of A. holmgreniorum.