Abstract
Japanese pear (Pyrus pyrifolia Nakai) ‘Gold Nijisseiki’ fruit were stored for 28 days at 0, 4, 10, 15, or 22°C. The effects of storage temperature on sucrose metabolism and on the expression of genes for sucrose-metabolizing enzymes were investigated. Fruit firmness, skin color, and content of various sugars were affected by storage temperature. Fruit stored at 22°C underwent rapid fruit softening and skin color change. Fruit stored at 15 or 10°C had lower sucrose content and higher glucose and fructose content than those stored at 0, 4, or 22°C. To investigate whether sucrose loss is related to changes in the expression of sucrose-metabolizing enzymes (vacuolar acid invertase: AIV; and sucrose phosphate synthase: SPS), we examined the expression of 3 genes during storage, namely, those encoding AIV (PpAIV1 and PpAIV2) and SPS (PpSPS1). Storage at 10 and 15°C increased the expression of PpAIV2 within a week and that of PpAIV1 in 14 days, while storage at 0 and 4°C delayed increased expression of PpAIV1 and PpAIV2 until after 28 days. Changes in the gene expression of sucrose-metabolizing enzymes were followed by delayed responses in sugar content.
