In vitro propagation and reintroduction of golden paintbrush (Castilleja levisecta), a critically imperilled plant species

Abstract

Golden paintbrush (Castilleja levisecta Greenm.) is a hemiparasitic 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 Murashige and Skoog basal medium with 2.0 μmol L−1 6-benzylaminopurine (BA), 3.0 μmol L−1 kinetin (Kn), 2.2 g L−1 phytagel, and 3% sucrose. Explant position on source plants, culture vessel design, and application of different plant growth regulator levels for BA, Kn, and thiadiazuron (TDZ) were tested 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, Victoria, BC, with 7.5% survival. The use of micropropagation in combination with reintroduction efforts offers an excellent opportunity for conserving endangered plant biodiversity in vitro and facilitating in situ conservation efforts by providing plants for reintroduction.

Saving threatened plant species: Reintroduction of Hill’s thistle (Cirsium hillii. (Canby) Fernald) to its natural habitat

“…Agab & Greuter and Isoplexis isabiliana (Webb & Berth) Masf. [18,19,[32][33][34]. Stunted shoots at high concentrations of BA have also been observed in other plant species [35].…”

“…prevent species loss in the field. Earlier we developed micropropagation methods for several threatened North American plant species including American elm, cherry birch, and golden paintbrush [18,19,24,25]. The current study referred to as the CPR model was undertaken to assess the potential of micropropagated plants in establishing new plant populations in a range of diverse natural habitats.…”

“…Micropropagation is emerging as an efficient tool that has been successfully used as a source of healthy plant material for reintroductions globally [15][16][17]. In Canada, micropropagation has also been applied to propagate plants for in vitro conservation of endangered plant species such as Betula lenta L. and Castilleja levisecta Greenm [18,19]. Micropropagation is a good approach for Hill's thistle because germplasm can be stored to conserve the limited genetic diversity in sterile conditions while the threats to the extant populations are managed through reintroduction of micropropagated plants.…”