Selection for Geosmin Production in Table Beet (Beta vulgaris ssp. Vulgaris)

The table beet (Beta vulgaris ssp. Vulgaris) is often characterized as having an earthy flavor and aroma. This is due to geosmin, C₁₂H₂₂O, a volatile terpenoid compound commonly produced by a class of soil microorganisms called actinomycetes. A survey of 11 table beet, 1 Swiss chard, 1 mangel, and 1 sugarbeet cultivar grown in autoclaved and non-autoclaved soil and in a field environment over two years revealed few significant changes in geosmin concentration rank, as measured by GC-MS, for individual cultivars across these disparate environments. These results suggest that geosmin content may be cultivar specific and may be less influenced by microbial association. These findings led to the creation of two breeding populations formed from cultivars that were highest and lowest in geosmin. Approximately 25 plants from each of the highest producing cultivars – ‘Bull’s Blood’ and ‘Chioggia’ were recombined for two generations using a half-sib family structure. An identical procedure was followed for the lowest geosmin-containing cultivars ‘Touchstone Gold’ and ‘Blankoma.’ Following the recombination phase, roots from individual half-sib families were evaluated for geosmin concentration. Significant inter root variation was found within each half-sib family. The highest and lowest geosmin-containing roots were selected for recombination and are now part of an ongoing half-sib family recurrent selection scheme. To assess whether table beet is capable of endogenous geosmin production, tissue culture experiments were conducted under sterile conditions. Cultured plants were evaluated for geosmin levels.