Elucidating mechanisms that cause potato glycoalkaloids to spike
Primary author: Moe Hnin Si
Co-author(s): Sen Lin; Roy Navarre
Primary college/unit: Agricultural, Human and Natural Resource Sciences
Campus: WSU-IAREC, Prosser, WA
Developing new potatoes with increased amounts of phytonutrients and low amounts of neurotoxic glycoalkaloids (GLKs) benefits for producers and consumers of potato. Light-induced accumulation of GLKs and concurrent greening tubers is a major problem in rejecting greening tubers from markets, which some have estimated can cause up to 15% -17% of the crop to be culled. Metabolite levels are genetically determined, but several factors such as environmental cues or tuber color can affect their final content. Transcriptomic and metabolomic approaches were applied to monitor levels of GLKs, chlorophyll, and carotenoids, and 32 target genes (biosynthetic genes and/or regulators) in potatoes exposed to light. Levels of GLKs were markedly spiked in eight white and two color flesh genotypes among the 20 studied (10 white and 10 color), exceeding the accepted limit of 20mg/100g FW. Other genotypes had less spiking of GLKs. Metabolic analysis across different genotypes showed color potato with higher amounts of carotenoids had less GLK spiking and revealed a possible mechanism of metabolite sharing by trading of isoprenoid intermediates between the cytosol and the plastid. Only four genotypes among those tested showed a positive correlation between greening and GLKs levels, implying that potatoes showing greening do not necessarily have higher GLKs content. We assessed the relative importance of transcriptional control at GLK regulatory points by assessing gene-gene, gene-metabolite and metabolite-metabolite correlations. These findings provide insights into mechanisms that control levels of GLKs and suggest potato breeding programs may benefit from evaluating spiking potential of breeding lines.