Glycoalkaloids and acclimation capacity of hybrids between Solanum tuberosum and the incongruent hardy species Solanum commersonii

F-1 and backcross hybrids between sexually incompatible species Solanum commersonii and Solanum tuberosum were characterized for glycoalkaloid content and capacity to cold acclimate. Glycoalkaloid (GA) analysis revealed that F-1 triploids and BC1 pentaploids contained the glycoalkaloids of both parents. In BC2 (near) tetraploids the situation was different, in that some hybrids produced the GAs of both parents, whereas others contained only the GAs of S. tuberosum. This suggested that the GAs from S. commersonii may be lost rapidly, and that they may have a simple genetic control. The total tuber GA content of BC1 and BC2 groups averaged quite acceptable levels (165.9 mg/kg in BC1 and 192.8 mg/kg in BC2), with six genotypes having a GA content <200 mg/kg fresh weight. The F-1 triploid hybrids expressed a capacity to cold acclimate similar to S. commersonii, whereas BC1 and BC2 genotypes generally displayed an acclimation capacity higher than the sensitive parent but lower than S. commersonii. However, one BC1 and two BC2 genotypes with an acclimation capacity as high as S. commersonii were identified. The polar lipid fatty acid composition in S. commersonii and its hybrid derivatives showed that, following acclimation, there was a significant increase in 18:3. Correlation analysis between the capacity to cold acclimate and the increase in 18:3 was significant, suggesting that the increase in 18:3 can be used as a biochemical marker for the assisted selection of cold-acclimating genotypes in segregating populations.