Properties of vacuolar acid invertase gene associated with sugar accumulation during low-temperature storage of potato tubers

Abstract

Low-temperature storage of potato tubers leads to an accumulation of reducing sugars. We have investigated that there are three types of sugar change among cultivars: an increased level of reducing sugars; low levels of reducing sugars; and increased sucrose, not reducing sugars. These patterns are related to the activities of vacuolar acid invertase. In this study, we performed cloning of cDNA for this enzyme, and genomic southern analysis among cultivars having different type of sugar changes (May Queen, White Fryer and Inca-no-mezame). cDNA from May Queen contained one open reading frame including β-fructosidase motif, peptide domain consisting of a Cys, and four potential glycosylation sites, which are highly conserved in acid invertases of plant origin. Southern blot analysis showed that the gene exists as a single-copy gene in all cultivars, and promoter region and/or non-coding region in Inca-no-mezame seem(s) to be different from those of other two cultivars.