In vitro propagation and re-introduction of Golden Paintbrush (Castilleja levisecta), a critically imperiled plant species

Golden paintbrush (Castilleja levisecta Greenm.) is a hemi-parasitic herbaceous perennial native to the Pacific Northwest of North America and is considered critically imperilled with only 11 populations remaining in the wild. The main objective of this study was to develop ex-situ and in situ conservation through micropropagation and field plantings. In vitro cultures were initiated using nodal explants from two plants raised from seeds collected from a natural population. Shoots were then multiplied on MS basal medium with 2.0 ÂľM BA, 3.0 ÂľM Kinetin, 2.2 g/L phytagel and 3% sucrose. Explant position on source plants, culture vessel design and application of different plant growth regulator levels for 6-Benzylaminopurine (BA), Kinetin (Kn) and Thiadiazuron (TDZ) were tested in order to optimize micropropagation protocols. Clones from the plants showed differences in plant height and number of nodes in response to various BA and TDZ concentrations. In vitro shoots were successfully rooted under ex-vitro conditions using commercial rooting powder (0.8% Indole-3-Butyric Acid) with an average of ~17 roots per shoot and acclimatized in the greenhouse with 100% survival rate. Two month old plants were transferred to a Parks Canada restoration site at Fort Rodd Hill, BC, Canada with 7.5% survival. The use of micropropagation in combination with re-introduction efforts offers an excellent opportunity for conserving endangered plant biodiversity in vitro and facilitating in situ conservation efforts by providing plants for re-introduction.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author