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Relative total phenolics in potato (Solanum tuberosum L.) progeny from 15 families


Potatoes are the fourth most important food crop by consumption in the world. Since antioxidants have been identified as having health benefits related to reducing free radicals, there is interest in increasing the levels of antioxidants in new potato cultivars. The objectives of this study were to: (1) Determine the total phenolics content (TPC) of progenies of 15 families derived from crosses of clones grown in the San Luis Valley (SLV), Colorado (CO). (2) Determine if pigment level as measured by MiniScan® XE Plus could be used as a method to identify high TPC tubers. (3) Study the correlation between TPC of all tubers and families' means harvested from the field with corresponding families' means and tubers harvested from the greenhouse (GH).
Progeny from 15 families were evaluated for TPC in the GH (448 progeny) and field (223 progeny) in the SLV, CO in 2007. MiniScan® XE Plus assay was also evaluated as a tool to select superior progeny for TPC in the GH. TPC of seedling tubers grown in the GH were also compared to TPC of the same tubers grown in the field. TPC was measured using Folin-Ciocalteu reagent and tuber flesh color was measured using the MiniScan® XE Plus from Hunter Lab (Reston, VA).
The TPC varied considerably among individual progeny lines of tubers grown in the GH and field and ranged from 1.74 to 17.94 and 1.82 to 19.38 mg Gallic Acid Equivalent (GAE)/g dry weight (DW), respectively. Three families (CO0463, CO04045, and C097307) were found to have the highest average TPC in the GH (7.43, 7.1, and 6.1 mg GAE/g DW) and field (14.45, 9.88, and 9.1 mg GAE/g DW) respectively. Most families' means and tubers exhibited a considerable increase in TPC in the field when compared to the same families' means and seedling tubers grown in the GH.
Correlation of TPC means of families grown in the GH with those grown in the field was r = 0.83 (P = 0.0002). However, correlation of TPC of all individual lines of tubers harvested from the field with corresponding seedling tubers harvested from the GH was r = 0.70 (P < 0.0001). In addition, the correlations between TPC for individual tubers grown in the GH and field within each family varied from r = -0.13 (P = 0.5) to -0.82 (P < 0.0001) within C004045 and C097306 families, respectively.
Color as determined by MiniScan® XE Plus was not useful as a tool to select superior progeny for TPC. Correlation of flesh color as indicated by L value and total phenolic content of 448 seedling tubers was moderate (r = -0.65, P < 0.0001) (L value ranges from 0 to 100, where 0 is black and 100 is white).
In conclusion, TPC of progeny in the greenhouse can be used to select among families but selections of superior individuals within families are better done in the field where greater overall levels of TPC are noted. Progenies of C00463, C004045, and C097307 families can be used to select for high TPC clones. Colored-fleshed potato clones were higher in TPC than white-fleshed clones. The highest TPC contents were observed in red-fleshed clones in the GH and field. Thus, the purple-fleshed potatoes are not necessarily higher in TPC than red-fleshed as previously reported by Reddivari et al. (2007). Many environmental factors such as higher light intensity, UV-B radiation, lower fertilizer rates applied, and large diurnal temperature differences in the field were likely factors associated with the differences in TPC observed between the GH and field.


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Solanum tuberosum
plant sciences


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