Location: Southern Horticultural ResearchTitle: Propagation and conservation of the federally endangered perennial species Pityopsis ruthii) Author
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2013
Publication Date: 2/1/2014
Citation: Wadl, P., Rinehart, T.A., Dattilo, A., Pistrang, M., Vito, L., Milstead, R., Trigiano, R. 2014. Propagation and conservation of the federally endangered perennial species Pityopsis ruthii. HortScience. 49:194-200. Interpretive Summary: Previous efforts to restore Ruth’s golden aster in suitable, unoccupied habitat were unsuccessful. The reasons for the experimental failures were not entirely clear, but the investigators recognized the potential for drought stress and soil disturbance to negatively impact reintroduced plants. Though the relative importance of these two factors in the survival of transplanted Ruth’s golden aster is unknown, some attempt to mitigate for drought stress and soil disturbance will be integral to restoring the species into the suitable habitat. The goal of this study was to refine the standard seed germination protocol, in vitro seed germination methodology, and vegetative propagation techniques, including in vitro multiplication of cloned plantlets, to facilitate ex situ conservation and development of a new methodology for restoring Ruth’s golden aster into suitable habitats.
Technical Abstract: Pityopsis ruthii is an endangered species endemic to the Hiwassee and Ocoee Rivers in Tennessee, United States. As part of a recovery effort focused on P. ruthii, vegetative propagation and in vitro multiplication techniques and seed germination were developed. Plants were vegetatively propagated using greenhouse stock plants and wild collected stems. Rooting occurred with and without auxin treatments, but was best when 0.1% indole-3-butyric acid (IBA) talc was applied to the cuttings; rooting was poorest with flowering stems. Pro-Mix BX substrate provided the most consistent rooting. Lateral shoots from in vitro grown plants were rooted on Murashige and Skoog (MS) basal medium, and 270 plantlets were produced from a single clone after 4 months. Acclimated plantlets were transplanted to their natural habitat and 14 of 19 plantlets survived one year. To avoid genetic swamping of native populations with the introduction of large numbers of genetically identical individuals via clonal propagation, seed based propagation efforts were explored. Open pollinated seeds were collected, disinfested and germinated and seedlings established on MS medium. Seeds were submersed in 70% ethanol for 1 min and briefly flamed. Seeds were surface sterilized in a range [10-to- 50% (v/v)] Clorox® bleach solutions with vigorous shaking for 20 min, rinsed three times in sterile water and germinated on MS basal medium. Removal of pappus from seeds was required for successful disinfestations, but the bleach concentration was not critical. Successful propagation is a step towards the conservation and recovery of P. ruthii and should allow future reintroduction projects.