Glycoalkaloid content and chemical composition of potatoes improved with non-conventional 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. Our results suggest that chitinase-gene insertion did
not alter other metabolic pathways of potato tubers without causing
unintentional pleiotropic effects. As far as interspecific hybrids are
concerned, wide variability for all 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 or lower than that of the control varieties, suggesting that selection
for low glycoalkaloid content is possible. Our results also indicated that
glycoalkaloids from S. commersonii may be lost rapidly. Indeed, we found
that some hybrids had the same glycoalkaloid profile as S. tuberosum.
Finally, 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.