Echinacea
The Wendel Laboratory is part of a national effort sponsored by the NIH to characterize botanicals that are taken as dietary or medicinal supplements. Iowa State University has received a 7.5 million dollar grant to help characterize Echinacea and Hypericum. As a laboratory with experience in systematics, we are working on reconstructing a nuclear sequence based phylogeny. To date, all phylogenies have been based on morphometric analysis, AFLP, or isozyme data.
As the popularity of Echinacea as an herbal supplement continues to rise, the necessity to characterize genetic architecture within the genus becomes increasingly important from three distinct perspectives. First, newly garnered understanding of which compounds are bioactive will invigorate breeding programs aimed at creating cultivars with high yields of medicinally important molecules. Such breeding programs will be greatly enhanced and expedited by a priori knowledge of populations harboring high levels of allelic diversity. Second, the availability of data regarding genetic diversity for all nine species will provide federal agencies with the ability to make informed decisions about protecting individual populations. Third, acquisition of haplotype data for the nine species will provide the power to test hypotheses regarding speciation and range expansion of the genus. Concomitant with the assessment of these population genetic parameters come the power to design tests to validate the purity of batches to be used in supplement production. In addition to assuring roots are from Echinacea species, such methodologies will provide Federal regulatory bodies with the tools to identify illicit collection of protected species or populations.
Echinacea and Humans
Human interaction with the genus Echinacea dates back to the earliest Native American medicinal practices, as the plant was used to treat a myriad of ailments (Hobbs 1994). In fact, the current expansive range of E. purpurea is largely attributed to seed dispersal or transplanting by Native Americans. While Native Americans have used the roots continually, the last 50 years have seen episodic surges in overall public demand for the root of E. pallida, E. angustifolia, and E. purpurea. In particular, European demand for Echinacea extract has spawned a large industry of collecting in the Midwest United States. E. purpurea is the sole cultivated species and, unfortunately, initial breeding attempts were conducted from single sampling events. Field production from this single sample took place during the 1920-1940s in Russia, and quickly spread to Germany and other Central European nations, and finally back to the US as a cultivated ornamental. Compounding the situation is E. pallida’s intractability to the domestication process. These factors, combined with episodic public demand, have kept large scale, farm type production to a minimum. Instead, most collection is accomplished on a pay-per-pound basis that is entirely unregulated by the Federal Government. Any protection the three capitalized species receive is from fortuitous coincidence within the boundaries of the state or federal park system or on commercial ranches.
Echinacea Systematics and Evolution
The genus Echinacea is comprised of nine species whose taxonomic affinities have been the subject of much confusion, and consequently, much revision. Chief characteristics ensconcing relationships include: diagnostic morphological characteristics that vary with day length, hybrid swarms, improper nomenclature use in crucial herbaria collections, varying levels of ploidy, numerous special forms, inappropriate identification of samples used in systematic analyses, and insufficient sampling in systematic analyses. Further frustrating analysis is the inability to polarize characters via the lack of an undisputed outgroup. As one might surmise, these confabulatory processes limit the ability to resolve species let alone evolutionary relationships within the genus.
Original Map from http://www.kbs.ukans.edu/people/kindscher/echinacea/maps.html
The 1990s, however, marked a turning point in the study of the genus. The branch of the USDA Germplasm Resource Network located in Ames, Iowa, established a thorough collection of all species’ germplasm to facilitate commercial use and academic study of Echinacea. A great strength of the collection is the thorough sampling throughout the range distributions of many of the nine species as well as sampling from unique populations whose taxanomic status is unknown or those representing hybrid swarms. In conjunction with the creation of the germplasm collection, work by Urbatsch and Jansen in 1995 identified Echinacea as a source of paraphylly within the subtribe Helianthinae (coneflowers); follow up work by Urbatsch et al. in 2000 identified Echinacea as potentially belonging to the subtribe Zinniiae and as sister to either Heliopsis, Zinnia or Sanvitalia. Binns et al. completed the most complete revision of the genus is 2002 by way of a 74 character morphometric analysis. While this study is based upon the most thorough sampling to date, the revision reduced the number of species in the genus from nine to four and is unlikely to reflect the generic genetic architecture present. Currently, the NIH study is likely to prove the most utile for elucidating genetic relationships within the genus as it based on multiple nuclear and chloroplast loci.