细胞壁代谢与琯溪蜜柚果实成熟过程汁胞粒化的关系

Relationship between Cell Wall Metabolism and Fruit Juicy Sac Granulation during Fruit Mature Stage of Pummelo [Citrus grandis (L.) Osbeck ‘Guanxi-miyou’]

摘要:

以易发生汁胞粒化的老龄树和不易发生汁胞粒化的适龄树的琯溪蜜柚(Citrus grandis (L.) Osbeck ‘Guanxi-miyou’)果实为材料，研究了果实成熟过程中汁胞粒化发生与细胞壁代谢的关系。结果表明：老龄树果实的汁胞粒化指数随着果实成熟而上升。在汁胞粒化发生过程中，汁胞维持较低的细胞壁降解酶[果胶甲酯酶(PE)、多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)]活性，保持较高的细胞壁物质(原果胶、纤维素、半纤维素)含量；尤其在汁胞粒化的起动阶段和加快阶段，纤维素、半纤维素含量极显著增加。相反，适龄树果实的汁胞粒化指数在果实成熟过程中变化不大，汁胞中细胞壁降解酶活性较高，促进原果胶、纤维素、半纤维素等细胞壁物质的降解，保持较低的细胞壁物质含量，使汁胞发育正常、柔软多汁。这说明PE、PG、Cx活性和原果胶、纤维素、半纤维素含量与琯溪蜜柚汁胞粒化密切相关。

Abstract:

Fruits of pummelo [Citrus grandis (L.) Osbeck ‘Guanxi-miyou’] from old-age trees occurred easily juicy sac granulation and proper-age trees not occurred juicy sac granulation were used to study the relationship between juicy sac granulation and cell wall metabolism during the fruit mature stage. The index of juicy sac granulation of fruits from the old-age trees increased with fruit maturing. Pectinesterase (PE), polygalacturonase (PG) and cellulase in juicy sacs kept low activities, and the contents of protopectin, cellulose and semicellulose were high during the development of juicy sac granulation. At the early and the rapid developmental stages of juicy sac granulation, the contents of cellulose and semicellulose were enhanced significantly. In contrast, the index of juicy sac granulation of fruits from the proper-age trees had little change with the fruit maturing. The activities of PE, PG and cellulase in juicy sacs were high and the contents of protopectin, cellulose and semicellulose were low. It suggested that the activities of PE, PG and cellulase, and the contents of protopectin, cellulose and semicellulose were closely related to juicy sac granulation of pummelo fruits.