Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2010
Publication Date: March 29, 2011
Citation: Wu, L., Bhasker, P.B., Zhang, R., Bethke, P.C., Busse, J.S., Jiang, J. 2011. Developing cold-chipping potato varieties by silencing the vacuolar invertase gene. Crop Science. 51(3):981-990. Interpretive Summary: Potato tubers used for the manufacture of potato chips and fries need to meet stringent quality control guidelines. One of the most important of these is a requirement that fried products are uniformly light colored after cooking. Storing potatoes at low temperatures results in a loss of tuber quality that leads to dark-colored, bitter tasting chips and fries that may have unacceptable amounts of acrylamide. Acrylamide is a compound found in carbohydrate-rich cooked at high temperatures and concerns have been raised recently about consumption of dietary acrylamide In this report we show that strongly reducing the activity of a single enzyme allows for low temperature storage of potato tubers without the accumulation of the sugars responsible for dark color and acrylamide formation. This approach was successful in each of the four cultivars used for the experiments. In all cases, tuber quality for a variety currently in commercial production was improved dramatically after low temperature storage. These data clearly define a specific target for improvement of potatoes that will benefit consumers and producers by improving tuber quality and the healthiness of finished potato products. Furthermore, waste caused by spoilage can be reduced since tubers can be stored at lower temperatures without a loss of quality.
Technical Abstract: Accumulation of reducing sugars during cold storage is a persistent and costly problem for the potato processing industry. High temperature processing of potato tubers with elevated amounts of reducing sugars results in potato chips, fries and other products that are unacceptable to consumers because of their bitter taste and unappealing dark color. More problematically, such products contain increased amounts of acrylamide, a neurotoxin and a potential carcinogen. We have demonstrated that silencing of the potato vacuolar acid invertase gene VInv can prevent reducing sugar accumulation in cold-stored tubers. Using this approach we developed Vinv gene silencing lines using RNA interference (RNAi) from four potato cultivars grown currently in the United States. All RNAi lines with >90% reduction of the Vinv transcripts showed minimum accumulation of reducing sugars during cold storage. Potato chips produced from these lines were light colored and had significantly lower acrylamide content compared to controls. Changes in growth and yield were not associated with VInv suppression using RNAi. We demonstrate that silencing of the Vinv gene is an effective approach to control the cold-induced sweetening problem in potato.