Abstract
Root chilling increases the sugar concentration of tomato fruit. Without affecting the pattern in which starch accumulated in early expansion stage and disappeared before ripening while fructose and glucose increased with the fruit development, root chilling enhanced the accumulation level of starch. The increase in starch accumuation in early expansion stage was almost comparable to the following increase in fructose and glucose in a single fruit. However, the expression of invertase genes, LIN5 and TIV1, was decresed by root chilling. To help define this apparent conflict, we compared the related enzyme activities. The activity of soluble acidic invertase showed similar pattern as the expression of TIV1 gene. On the other hand, cell wall-bound neutral invertase activity was slightly increased by root-chilling, unlike the expression pattern of LIN5 gene. Sucrose phosphate synthase (SPS) and sucrose phospathase (SPP) was enhanced by root-chilling in early expansion stage. However sucrose synthase (SuSy) activity was not enhanced.
