A comparative study of bioactive secondary metabolite production in diploid and tetraploid Echinacea purpurea (L.) Moench

The impact of the ploidy level on biomass accumulation and the production of high-value secondary metabolites was studied in Echinacea purpurea (L.) Moench. Tetraploid E. purpurea was obtained by treating diploid explants with colchicine. The morphology, biomass yield, the contents of caffeic acid derivatives and alkamides, and the activities of phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) were compared between diploid plants and tetraploid plants of E. purpurea. The total fresh root weight and total dry root weight of the tetraploid plants were 39.32 and 40.48 % higher than those of the diploid plants, respectively. The chemical profiles of the diploid and tetraploid E. purpurea plants were similar, as determined through a comparison of their FTIR spectra and second derivative spectra. The caffeic acid derivatives and alkamides in the diploid and tetraploid plants were determined by HPLC. The tetraploid plants had higher contents of both of these types of molecules. In addition, the tetraploid plants had higher PAL and C4H activities compared with the diploid plants. The enhancement in the PAL and C4H activities was accompanied with an increase in the cichoric acid content, which indicates that the induction of polyploidy in E. purpurea resulted in higher PAL and C4H expression and promoted the biosynthesis of cichoric acid. Therefore, the induction of polyploidy may be a valid strategy to achieve a higher yield of biomass and bioactive compounds in E. purpurea.