The genus Pityopsis is comprised of seven perennial species and can be found in the eastern United States, southeast Mexico, Bahamas, and Central America (Belize, Guatemala, and Honduras) (Semple, 2006). Pityopsis ruthii (Ruth’s golden aster) is listed under the Endangered Species Act (ESA) and occurs only along two small reaches of the Ocoee and Hiwassee Rivers in Polk County, TN. It grows in crevices on exposed phyllite and graywacke rocks that are in and between the river channel and the adjacent forested slopes. The most recent census of Ruth’s golden aster populations counted ≈11,150 plants; more than 90% occur along the Hiwassee River (Tennessee Valley Authority, unpublished data).
Despite its critically imperiled status, as evidenced by its small overall population and narrow geographical range, there has been relatively little applied research focused specifically on species recovery. However, the U.S. Fish and Wildlife Service, which is the federal agency charged with safeguarding species listed under the ESA, has outlined recovery criteria for Ruth’s golden aster that highlight the most critical data gaps and research needs [U.S. Fish and Wildlife Service (USFWS), 1992]. The most recent review of the species status cites a continuing need for better ex situ conservation efforts and additional research focused on restoration of Ruth’s golden aster in suitable habitat (USFWS, 2012).
Previous ex situ conservation efforts for Ruth’s golden aster have been focused entirely on long-term seed storage (USFWS, 2012). Provided seeds are available and germinate readily, seed-based methods are often the most efficient means for ex situ conservation (Pence, 2011). However, wild-collected Ruth’s golden aster seeds often exhibit poor germination and produce seedlings with low vigor (Clebsch and Sloan, 1993; Cruzan, 2001; Farmer, 1977; White, 1977). To overcome the limitations of propagating solely with seed and to provide increased flexibility in ex situ conservation efforts, an in vitro propagation protocol was developed (Wadl et al., 2011). Whereas Wadl et al. (2011) demonstrated the capability to produce plants in vitro, further refinement of current techniques is needed to ensure reliable propagation. Although propagating Ruth’s golden aster from seed can be problematic, using seed has the advantage of producing genetically diverse propagules instead of clonal plants, which is essential to minimizing the potential for genetic swamping when producing plants for ex situ conservation and restoration.
Previous efforts to restore Ruth’s golden aster in a suitable, unoccupied habitat were unsuccessful. Cruzan and Beaty (1998) performed several experimental plantings, but after two growing seasons, almost 100% of the transplants had died. 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. Although 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 a 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 habitat.
AtkinsonK.LacroixC.2013Evaluating reintroduction methods for the Gulf of Saint Lawrence aster (Symphyotrichum laurentianum) on Prince Edward IslandBotany91293299
ClebschE.E.C.SloanA.1993Final report contract between the University of Tennessee and the Tennessee Department of Environment and Conservation for the study of various aspects of the ecology and life history of the endangered plant species Ruth’s golden aster (Pityopsis ruthii). Rpt. Tennessee Dept. Environ. Conservation
CruzanM.B.2001Ecological genetics of Pityopsis ruthii: Final research report I. Reproductive ecology. Unpublished report. Tennessee Dept. Environ. Conservation Div. Natural Heritage
CruzanM.B.BeatyP.1998Population biology of Ruth’s golden aster (Pityopsis ruthii). Rpt. Tennessee Dept. Environ. Conservation Div. Natural Heritage ID-96-05937-6-00
CruzanM.B.EstillJ.C.2001Ecological genetics of Pityopsis ruthii: Final research report. II. Phylogeography. Unpublished report. Tennessee Dept. Environ. Conservation Div. Natural Heritage
FreyB.KemplerC.EhertD.L.2007Micro-propagation of White-top aster, Sericocarpus rigidus, a threatened species from the Garry Oak ecosystem in British ColumbiaCan. Field Nat.1214045
FritschP.RiesebergL.H.1996The use of random amplified polymorphic DNA (RAPD) in conservation genetics p. 54–73. In: Smith T.B. and R.K. Wayne (eds.). Molecular genetics approaches in conservation genetics. Oxford University Press New York NY
HomoyaM.A.AbrellD.B.2005A natural occurrence of the federally endangered Short's goldenrod (Solidago shortii T. & G.) [Asteraceae] in Indiana: Its discovery, habitat, and associated floraCastanea70255262
HonnayO.JacquemynH.2007Susceptibility of rare and common plant species to the genetic consequences of habitat fragmentationConservation Biol21824831
JoshiM.DharU.2003In vitro propagation of Saussurea obvallata (DC.) Edgew.—An endangered ethnoreligious medicinal herb of HimalayaPlant Cell Rpt.21933939
KesslerJ.R.JrKeeverG.J.2007Plant growth retardants affect growth and flowering of Coreopsis verticillata ‘Moonbeam’J. Envir. Hort.25229233
LesD.H.ReinartzJ.A.EsselmanE.J.1991Genetic consequences of rarity in Aster furcatus (Asteraceae), a threatened, self-incompatible plantEvolution4516411650
LynchS.JohnstonR.K.DetermannR.O.Cruse-SandersJ.M.PullmanG.S.2013Seed cryostorage and micropropagation of Georgia aster, Symphyotrichum georgianum (Alexander) Nesom: A threatened species from the southeastern United StatesHortScience48750755
OzelC.A.KhawarK.M.MiriciS.ArslanO.OzcanS.2006Induction of ex vitro adventitious roots on softwood cuttings of Centaurea tchihatcheffii Fisch et. Mey using indole 3-butyric acid and α-naphthalene acetic acidIntl. J. Agr. Biol.86669
PaceL.G.BrunoA.A.SpanòL.2009In vitro plant regeneration and clonal micropropagation of Leontopodium nivale (Ten.) Heut ex Hand.-Mazz. (Asteraceae)Plant Biosyst.143S12S16
SempleJ.C.2006Treatment of Pityopsis p. 222–228. In: Flora of North America Editorial Committee (ed.) Volume 20 Magnoliophyta: Asteridae part 7: Asteraceae part 2. Oxford University Press New York NY
SharrockS.2012Global strategy for plant conservation. A guide to the GSPC all the targets objectives and facts. Botanic Garden Conservation International Richmond UK
SloanS.A.1994Allozyme variation within and between populations of Ruth's Golden Aster Pityopsis ruthii (Small) Small. MS Thesis Univ. of Tenn. Knoxville
United States Fish and Wildlife Service1992Ruth’s golden aster recovery plan. Atlanta GA
United States Fish and Wildlife Service2008Jesup’s milk-vetch (Astragalus robbinsii var. jesupii) 5-year review: Summary and evaluation. U.S. Fish and Wildlife Serv. Concord NH
United States Fish and Wildlife Service2012Ruth’s golden aster (Pityopsis ruthii) 5-year review: Summary and evaluation. U.S. Fish and Wildlife Serv. Cookeville TN
WadlP.A.DattiloA.J.VitoL.M.TrigianoR.N.2011Shoot organogenesis and plant regeneration in Pityopsis ruthiiPlant Cell Tissue Organ Cult.106513516
WalterK.S.GillettH.J.19981997 IUCN red list of threatened plants compiled by the world conservation monitoring centre IUNC. The World Conservation Union Gland Switzerland and Cambridge UK
WellsE.F.2012Reintroduction of federally endangered harperella (Harperella nodosum Rose) in flood-prone, artificial, and natural habitatsCastanea77146157
WhiteA.J.1977An autecological study of the endangered species Heterotheca ruthii (Small) Harms. MS thesis Univ. Tennessee Knoxville TN