Submitted to: American Journal of Potato Research
Publication Type: Abstract only
Publication Acceptance Date: 4/15/2008
Publication Date: 4/1/2009
Citation: Ndambe, M.M., Bamberg, J.B., Miller, J.C. 2009. Glycoalkaloid Levels in Solanum Microdontum and S. Jamesii Accessions: A Consideration in Parental Selection When Breeding for High Antioxidant Activity in Potato. American Journal of Potato Research [abstract]. 86:154. Interpretive Summary:
Technical Abstract: Antioxidants are useful in reducing risk of several diseases associated with free radicals. While potatoes are not as high in antioxidants as fruits, the fact that large quantities of potatoes are consumed (~130 lbs per capita) suggests that any increase in tuber antioxidants would greatly benefit human nutrition. Certain accessions of tuber-bearing wild potato species (S. jamesii, S. pinnatisectum, S. megistacrolobum, and S. microdontum) are higher in antioxidant activity (AOA) and total phenolics (TP) than commercially grown potato cultivars, and could be potential sources of genes in breeding for high AOA. However, most wild species are reported to contain high levels (>200 mg/kg) of glycoalkaloids which are toxic to humans. Hence, use of wild species as parental material in breeding for high AOA and TP might also result in progenies with unacceptable glycoalkaloid (TGA) levels, if the traits are positively correlated. Therefore, the objective of this study was to screen all accessions of S. jamesii and S. microdontum in the US Potato Genebank (NPGB) for AOA, TP, TGA, individual phenolics and glycoalkaloids, and investigate their correlations. Ninety-two S. jamesii and 86 S. microdontum accessions were obtained from the USPG, Sturgeon Bay, WI. The DPPH and ABTS assays were used to evaluate AOA, while TP was estimated using the Folin-Ciocalteau method. Individual phenolics and glycoalkaloids were analyzed with HPLC. The glycoalkaloids a-solanine and a-chaconine were found in both S. jamesii and S. microdontum, while tomatine and dehydrotomatine were quantified in several S. microdontum accessions, but not in S. jamesii. Accessions of S. microdontum were higher in all traits measured than S. jamesii, and both species were higher than the cultivars Atlantic, Red LaSoda, and Yukon Gold. More than 90% of S. jamesii accessions had TGA levels < 200 mg/kg, while only 2 (P1 500041 and PI 473171) of the 86 S. microdontum accessions exhibited TGA content < 200 mg/kg. Significant correlations were observed between AOA and TP in S. jamesii (r = 0.8) and S. microdontum (r = 0.9). However, neither AOA nor TP was significantly correlated with TGA in S. jamesii (r = 0.026 and 0.132) and in S. microdontum (r = 0.248 and 0.274). Also chlorogenic acid, caffeic acid, rutin hydrate, and myricetin were not significantly correlated with TGA in either S. jamesii or S. microdontum. Therefore, since AOA and TP are not correlated with TGA, using wild accessions in breeding for high AOA would not necessarily increase glycoalkaloids in newly developed potato cultivars.