Location: Vegetable Crops Research Unit
Title: Cold-induced sweetening, sugar ends, stem-end chip defect and acrylamide can be controlled effectively by silencing of the potato vacuolar invertase gene Authors
Submitted to: Proceedings Wisconsin Annual Potato Meetings
Publication Type: Proceedings
Publication Acceptance Date: January 24, 2013
Publication Date: February 5, 2013
Citation: Bethke, P.C., Zhu, X., Wiberley-Bradford, A.E., Bussan, A.J., Jiang, J. 2013. Cold-induced sweetening, sugar ends, stem-end chip defect and acrylamide can be controlled effectively by silencing of the potato vacuolar invertase gene [abstract]. Proceedings Wisconsin Annual Potato Meetings. p. 151. Technical Abstract: Potato (Solanum tuberosum) is the third most important food crop in the world. Processing quality is one of the most important traits for many potato cultivars. Accumulations of reducing sugars in whole tubers as a result of cold-induced sweetening during low temperature storage, or at the tuber stem-end in the case of sugar-end defect tubers or stem-end chip defect tubers, decreases processing quality and crop value. During high-temperature cooking, reducing sugars react with free amino acids to produce brown- to black-pigmented products and acrylamide. Acrylamide is a neurotoxin and a suspected carcinogen that is formed from reducing sugars and the amino acid asparagine. The most effective way to reduce acrylamide formation in process potato products would be to develop potato varieties with low concentrations of reducing sugars and/or free asparagine. Our previous research focused on potato chips and demonstrated that both the cold-induced sweetening and acrylamide problems can be controlled effectively through the development of vacuolar invertase gene (VInv) silencing lines of potato. We have expanded this area of research and developed a total of 50 VInv-silencing lines of Russet Burbank. In these lines, the amount of VInv mRNA was reduced 0-20% in 14 lines, 20-40% in 3 lines, 40-60% in 4 lines, 60-80% in 7 lines and 80-100% in 22 lines. Five RNAi lines with different degrees of VInv gene silencing were grown in the field at the Hancock research station in 2012. Appearance of the plants and tubers was similar to that of Russet Burbank. Tubers had lower contents of reducing sugars in both ends of the tuber, and fried potato slices from the RNAi lines were light in color. Remarkably, the severe sugar-end defects observed in control Russet Burbank were not apparent in several RNAi lines. Similarly, chipping potato varieties with reduced expression of VInv have a large reduction in stem-end chip defects when compared to control varieties. Thus, silencing of the VInv gene can improve significantly the processing quality of chip and fry processing varieties, and in doing so decrease their acrylamide-forming potential.