Post‐translational regulation of acid invertase activity by vacuolar invertase inhibitor affects resistance to cold‐induced sweetening of potato tubers

• Published in: Plant, cell and environment Vol. 36; no. 1; pp. 176 - 185
• Main Authors: MCKENZIE, MARIAN J, CHEN, RONAN K. Y, HARRIS, JOHN C, ASHWORTH, MATTHEW J, BRUMMELL, DAVID A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2013; Blackwell; Wiley Subscription Services, Inc
• Subjects: acrylamide; Acrylamide - analysis; acrylamides; asparagine; beta-fructofuranosidase; beta-Fructofuranosidase - metabolism; Biological and medical sciences; cold; cold storage; Cold Temperature; Color; cultivars; fructose; frying; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; gene overexpression; genes; glucose; Maillard reaction; pathogenesis; Plant Proteins - metabolism; Plant Tubers - chemistry; Plant Tubers - enzymology; potatoes; Protein Processing, Post-Translational; reducing sugars; RNA, Messenger - metabolism; roasting; Solanum tuberosum; Solanum tuberosum - chemistry; Solanum tuberosum - enzymology; sprouting; starch; sucrose; temperature; tubers; acrylamide; Cold; Enzyme; Solanum tuberosum; β-Fructofuranosidase; Plant ecology; Vacuole; Glycosylases; Resistance; Potato; Reducing sugar; Dicotyledones; Glycosidases; reducing sugars; Angiospermae; Tuber; Hydrolases; Spermatophyta; Inhibitor; Tuber plant; Solanaceae
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2012.02565.x

Cold‐induced sweetening (CIS) is a serious post‐harvest problem for potato tubers, which need to be stored cold to prevent sprouting and pathogenesis in order to maintain supply throughout the year. During storage at cold temperatures (below 10 °C), many cultivars accumulate free reducing sugars derived from a breakdown of starch to sucrose that is ultimately cleaved by acid invertase to produce glucose and fructose. When affected tubers are processed by frying or roasting, these reducing sugars react with free asparagine by the Maillard reaction, resulting in unacceptably dark‐coloured and bitter‐tasting product and generating the probable carcinogen acrylamide as a by‐product. We have previously identified a vacuolar invertase inhibitor (INH2) whose expression correlates both with low acid invertase activity and with resistance to CIS. Here we show that, during cold storage, overexpression of the INH2 vacuolar invertase inhibitor gene in CIS‐susceptible potato tubers reduced acid invertase activity, the accumulation of reducing sugars and the generation of acrylamide in subsequent fry tests. Conversely, suppression of vacuolar invertase inhibitor expression in a CIS‐resistant line increased susceptibility to CIS. The results show that post‐translational regulation of acid invertase by the vacuolar invertase inhibitor is an important component of resistance to CIS.