Fungal mutualists enhance growth and phytochemical content in Echinacea purpurea
Gualandi, R.J., Jr, R. M. Auge, D. A. Kopsell, B. H. Ownley, F. Chen, H. D. Toler, M. E. Dee, and K. D. Gwinn.  2014.  Symbiosis, 63:111-121.

An emerging paradigm in sustainable biotechnique is the use of mutualists to enhance plant growth and secondary metabolism. Our objective was to determine impact of two classes of fungal mutualists on growth and phytochemistry of Echinacea purpurea. Growth, development, and phytochemical concentration were measured in greenhouse-grown 12-week-old plants colonized by arbuscular mycorrhizal fungi (AMF) (Glomus intraradices and Gigaspora margarita) or the endophytic entomopathogen, Beauveria bassiana. In the first experiment, all measured growth parameters were increased in mycorrhizal plants. Biomass of AMF-colonized plants was over 13-fold greater than non-mycorrhizal controls receiving the same levels of phosphorous, and over 4-fold greater than non-mycorrhizal controls given additional phosphorous. Endophytic colonization by B. bassiana had minor effects on growth. Colonization by AMF and B. bassiana alone or in combination altered concentrations of phytochemicals (pigments, polyphenolics, alkylamides, and terpenes). Mycorrhizal plants produced up to 4.6-fold higher concentration of polyphenolics. Plants colonized with B. bassiana and receiving no additional phosphate displayed up to 1.7-fold increases in specific alkylamides, and plants treated with both mutualists had up to a 2.4-fold increase. Changes in other phytochemical classes were related to differences in plant size induced by AMF. Phytochemical content (concentration biomass) was increased up to 30-fold in colonized plants. Phytochemical relationships to biomass were confirmed in a second experiment in which non-mycorrhizal AMF plants were given supplemental fertilization to produce plants with biomass equivalent to AMF-colonized plants. This work has major implications for the natural product industries and growers of E. purpurea.