Advances in Echinacea Biotechnology and Future Prospects
Echinacea (Asteraceae) plant products are among the most popular herbal supplements. Of the nine species assigned to the genus, E. angustifolia, E. pallida, and E. purpurea are the species most commonly used in commercial products. The content of bioactive constituents varies qualitatively and quantitively among Echinacea populations, chemoraces, cultivars, and species; the content also varies seasonally, with plant age, and among the plant parts. Echinacea producers face numerous challenges, including breaking seed dormancy, low germination rates, fungal and viral diseases, and relatively long maturation times. Commercial products may vary in the chemotype(s) of the species or combination of species used, the plant part(s) used processing and extraction conditions, and preparation form of the finished product. As all of these factors influence the chemical profile of the final product, the production of consistent, high-quality products is an ongoing challenge for manufacturers. Finding solutions to these production and manufacturing challenges has been the focus of considerable Echinacea biotechnology research and development. In this review, the advantages and disadvantages of various biotechnologies for optimizing Echinacea propagation, standardization, production processes, and product quality are discussed, and promising new applications to promote market diversification and sustainability are highlighted.
Traditional methods of Echinacea propagation from seed, crown divisions, and root cuttings are time-consuming processes with limited potential for producing large numbers of plants and can result in genetically variable plant material. Much research has focused on cell culture micropropagation techniques, which allow more rapid production of large numbers of genetically identical plants, year-round cultivation, development of isogenic lines with more consistent secondary metabolite profiles, the production of unique chemical profiles, and reduced exposure to microbial pathogens. However, the process is labor-intensive, requires trained personnel, and the facility and equipment start-up costs are significant.
Bioreactors represent an alternative way to make tissue culture methods viable on a large scale. Bioreactors can mass-produce clonal materials of hundreds to tens of thousands of plants, making them suitable for use in genetic improvement programs. Biomass production often decreases at larger quantities, so strategies such as medium replenishment are used to improve production and phytochemical content. Although the cost of bioreactor culture is high because it requires specialized materials, facilities, and personnel training, “bioreactors offer a means of producing standardized plant material at a scale unmatched by field production,” write the authors. Although not commonly used in commercial production, the use of bioreactors is standard practice at an experimental scale.
Direct alteration of a plant’s genetic material by molecular genetic techniques can modify developmental and biosynthetic processes. “Organically acceptable” biotechnological approaches to modify Echinacea include the induction of polyploids and bacterial transformation. Hairy root culture uses the inherent ability of some soil bacterium to infect and transform plant tissue. Advantages of hairy root culture include accelerated growth, spontaneous regeneration of shoots, genetic stability, and constant production of high levels of metabolites can be maintained over a long period of time. “The rapid growth of hairy root cultures on hormone-free media makes them an excellent way to generate biomass quickly, or to clonally propagate plants,” state the authors. However, public acceptance of genetically modified material may limit the application of this technology.
Other methods to enhance the production of secondary metabolites in Echinacea cultures are being studied, including manipulating factors of the growing environment, such as the growth medium and light regime, abiotic treatments like ultrasound or increased ultraviolet A and B exposure that cause physical cellular damage, symbiotic endophytes, and the use of elicitors, such as plant hormones, stress signaling molecules and mediators, herbicides, biotics such as yeast extract, and abiotic compounds such as titanium ascorbate. Elicitors are easy to use, can be applied to cultures or field-grown crops, improve phytochemical content, and in some cases, also improve yield.
Elicitors are used to activate a plant’s defense response, which leads to increased production of many bioactive phytoconstituents. However, elicitors can also decrease yield, the timing of application can be critical, and consumers may not accept the use of herbicides and abiotic. “Commercial use of elicitors needs to balance secondary product yields against cost and the potential residual toxicity of an elicitor remaining in the harvested tissue,” note the authors.
Emerging market opportunities for Echinacea include additives in animal feed, which have been associated with improved immune activity and vaccine efficacy. There is also the potential to develop new markets for Echinacea essential oil, seed, and seed oil. Seed oils from all three commercial species are rich in oleic acid, palmitic acid, linoleic acid, vitamin E, and other bioactive compounds. Echinacea essential oil contains medicinal compounds with antimicrobial properties. “Echinacea seed oil and essential oils also have the potential to become successful product lines within the Echinacea industry,” state the authors.
Biotechnologies provide many options to improve Echinacea products. “The benefits and drawbacks of each of these approaches should be considered in terms of improvements in yield, optimization, and standardization of phytochemistry, propagation efficiency, cost, public perception and ease of use at scale,” write the authors. “Moving forward, a combination of tissue culture, chemical treatments, and traditional field cultivation will likely be used to generate a new higher standard of production and phytochemical quality,” the authors conclude. “These advances will provide the opportunity to establish a greater variety of Echinacea products to keep up with ever-expanding market opportunities.”
Parsons JL, Cameron SI, Harris CS, Smith ML. Echinacea biotechnology: advances, commercialization and future considerations. Pharm Biol. December 2018;56(1):485-494. doi: 10.1080/13880209.2018.1501583.