Diploid and tetraploid Centaurium erythraea Rafn: a comparative study of regenerative in vitro potential and biosynthetic capacity

Abstract

Polyploidy, or duplication of the entire genomes, is a widespread mechanism in plants which can lead to changes in cytological, biochemical, physiological and developmental characteristics, including conspicuous changes in morphology and metabolite production. In this study, we examined the impact of ploidy level on regenerative in vitro potential and biosynthetic capacity of C. erythraea plants. Ten genotypes of diploid (2x) and autotetraploid (4x) centaury, with ploidy levels confirmed by flow cytometry, were randomly selected from in vitro pool of seedlings maintained on hormone-free half-strength MS medium (½ MS). Root explants were excised either from basal, middle or apical root zone of 3 month-old plants. In vitro morphogenesis was induced on ½ MS medium. The frequency of shoot regeneration and the average number of shoots per root explant were recorded after 5 weeks in culture. Regeneration frequency was genotype dependent, but not affected by explant ploidy level. Regeneration efficiency declined from the apical to the basal root segment. Regenerated shoots were transferred onto ½ MS medium for rooting. Iridoid glycosides (loganic acid, loganin), secoiridoid glycosides (secologanin, sweroside, swertiamarin, gentiopicrin) and xantones (decussatin, eustomin, methylbellidifolin, desmethyleustomin) were quantified in shoots and roots of two month-old plants using targeted UHPLC-qqqMS analysis. Interestingly, diploid plants showed higher biosynthetic capacity for the production of secoiridoids and xanthones in both shoots and roots. Furthermore, two month-old shoots of 2x genotypes produced higher shoot and root biomass than 4x plants. Results highlight a great potential of diploid C. erythraea genotypes for biotechnology-based sustainable production of secoiridoids.