Variation for tuber composition, chip color, and invertase SNPs in cold stored Solanum germplasm

Dark color and acrylamide produced during potato chip processing can be minimized by limiting substrate availability for the Maillard reaction via introgression of wild Solanum germplasm that does not undergo extreme cold-induced sweetening. This statement assumes that: (1) Chip color correlates with tuber sugar or amino acid concentrations, and (2) Genotypes with light chip color or low reducing sugar concentrations from cold storage can be efficiently identified from Solanum species. This research is the first to examine the former assumption in wild Solanum. Many wild species had high sugar concentrations after cold storage, and fried chips accumulated brown pigments. Tuber sugar profiles implicated invertase activity in cold-induced sweetening in wild and cultivated potato. Reducing sugar and sucrose concentrations partially explained chip color variation in most accessions, but asparagine concentration and percent dry matter did not. S. pinnatisectum sugar profiles and tuber composition to chip color relationships were unique. Extensive inter- and intra-specific variation for chip color and tuber composition was observed, and genotypic and environmental variance was significant. Species with significantly lighter chip color than others included in this experiment were identified, but fine-screening of accessions will be required to identify genotypes for use in a breeding program. Experimental replication over years or locations reduced the variance of genotype mean chip color and tuber composition more than sampling, as determined by a resource allocation analysis, so future germplasm evaluations should include experimental replication to effectively identify superior genotypes. Two nucleotide polymorphisms in invertaseGE that associated with reducing sugar concentration after cold storage could improve selection efficiency.