Abstract:

【Objective】 The relationship between granulation and active oxygen metabolism of juice sac in pummelo [Citrus grandis (L.) Osbeck cv. Guanximiyou] fruit during maturation was investigated. 【Method】 Fruits of pummelo from old trees with higher ratio of juice sac granulation fruits, that with normal fruits, and optimum-aged trees with lower ratio of granulation fruits and that with normal fruits were used to study the changes in contents of MDA, H2O2, and lignin, activities of reactive-oxygen-scavenging enzymes (POD, SOD, CAT), and contents of endogenous antioxidants (AsA, GSH) in process of juice sac granulation. 【Result】 The index of juice sac granulation and contents of H2O2 and MDA increased while contents of ASA and GSH decreased, whereas SOD activity first declined and then increased and CAT activity increased, but POD activity rose more significantly in the fruits from the old trees in contrast to optimum-aged trees.【Conclusion】The results suggest that the disorder of active oxygen metabolism of juice sac of pummelo fruit during maturation may result in the accumulation of active oxygen (H2O2) and the increase of POD activity, which promote the synthesis of lignin, and finally cause juice sac granulation.

Key words: pummelo [Citrus grandis (L.) Osbeck cv. Guanximiyou], fruit, juice sac, granulation, active oxygen metabolism, lignin