Glycoalkaloid content and chemical composition of potatoes improved with nonconventional breeding approaches.

This paper reports the results of chemical analyses performed on two distinct groups of new potato genotypes. The first group contained five clones transformed with the gene ech42 encoding for an endochitinase. The second included 21 interspecific hybrids between the cultivated potato Solanum tuberosum and the wild species S. commersonii, obtained either by somatic fusion or by sexual hybridization. Tubers from transgenic plants were analyzed for several morphological and biochemical parameters to ascertain the substantial equivalence between the transgenic genotypes and the original cultivar Désirée. The interspecific hybrids were analyzed for the same parameters in order to identify genotypes with novel improved chemical characteristics and with low levels of glycoalkaloids deriving from the wild species and potentially hazardous to human health. For transgenic tubers, the results provided evidence that indicates the substantial equivalence between the transgenic genotypes and the cultivated control for the considered traits. The results suggest that chitinase gene insertion did not alter other metabolic pathways of potato tubers and did not cause unintentional pleiotropic effects. As far as interspecific hybrids are concerned, wide variability for all of the parameters analyzed was found. For some useful traits (e.g., soluble solids and proteins, dry matter content) the interspecific hybrids performed better than both the cultivated control and the wild species. In a number of genotypes, glycoalkaloid levels were close to or lower than those of the control varieties, suggesting that selection for low glycoalkaloid content is possible. The results also indicated that glycoalkaloids from S. commersonii may be lost rapidly. Indeed, some hybrids were found to have the same glycoalkaloid profile as S. tuberosum. Finally, the results showed that among the parameters considered, glycoalkaloid content is the most sensitive to variation. Therefore, glycoalkaloid determination should be used for routine control of genotypes produced by interspecific hybridization.