Soluble sugar content and key enzyme activity and the relationship between sugar metabolism and lipid accumulation in developing fruit of Camellia oleifera.

In order to decipher the potential relationship between soluble sugar content and lipid accumulation during Camellia oleifera fruit development, soluble sugar content and sucrose metabolizing enzyme activities of Camellia oleifera ‘Xianglin 11'fruit flesh were determined and the relationship between oil content in seeds and above indicators were analyzed. The fruit flesh showed a low soluble sugar level at the early developmental stage and reached peak in mid-June, followed by decline until mid-August. Acid invertases displayed high activities at the early stage. In contrast to cell wall acid invertase (CAI), soluble acid invertase (SAI) had a higher enzyme activities at late developmental stage compared with that of early stage, showing the active processes of translation and preservation of sucrose in vacuole during the period. Sucrose synthase activity (SS) showed the same variation trend as that of sucrose phospholylase (SPS) during the whole developmental stages. Further correlation analysis showed that the content of soluble sugar and glucose and lipid accumulation were significantly negatively correlated at P 0郾05 level, whereas the content of sucrose and lipid accumulation were significantly negatively correlated at P 0.01 level. Both SAI and CAI showed a significant positive correlation at P 0.05 level with lipid accumulation. Since oil translation in seeds coincides with active sugar metabolism processes of flesh during C. oleifera fruit development, it is recommended that field management at late developmental stage should be strengthened to improve oil production.