Tuber-Specific Silencing of the Acid Invertase Gene Substantially Lowers the Acrylamide-Forming Potential of Potato

Abstract

Some popular processed foods including French fries contain small amounts of toxic acrylamide. Efforts to lower the accumulation of this reactive compound by modifying the production process have a negative effect on sensory characteristics and are not broadly applicable. This study optimized a method developed more than a decade ago to lower the accumulation of the acrylamide precursors glucose and fructose in cold-stored tubers. In contrast to the original application, which lowered hexose content by one-third through constitutive expression of an antisense copy of the cold-inducible acid invertase (Inv) gene, the current approach was based on tuber-specific expression of an Inv-derived inverted repeat. Stored tubers of transgenic plants contained as little as 2% of the reducing sugars that accumulated in controls. This decline in glucose and fructose formation is counterbalanced by increased sucrose and starch levels. However, it did not trigger any phenotypic changes and also did not affect the formation of free asparagine, ascorbic acid, phenylalanine, and chlorogenic acid. Importantly, French fries from the low-invertase tubers contained up to 8-fold reduced amounts of acrylamide. Given the important role of processed potato products in the modern Western diet, a replacement of current varieties with the low-hexose potatoes would reduce the average daily intake of acrylamide by one-fourth.