ABSTRACT Here, the L-ascorbic acid (AsA) content as well as activities of enzymes and genes in AsA biosynthesis were investigated in bagged and unbagged fruit of Pyrus pyrifolia ‘Cuiguan’ during on-tree development. The contents of AsA/dehydroascorbate (DHA) and glutathione (γ-glutamyl-L-cysteinylglycine, GSH)/oxidised glutathione (GSSG) couples, the enzyme activities of L-galactono-1,4-lactone dehydrogenase (GLDH; EC 1.3.2.3), L-galactose dehydrogenase (GalDH; EC 1.1.1.117), ascorbate peroxidase (APX; EC 1.11.1.11), monodehydroascorbate reductase (MDHAR; EC 1.6.5.4), glutathione-dependent dehydroascorbate reductase (DHAR; EC 1.8.5.1) and glutathione reductase (GR; EC 1.6.4.2), and the relative expression levels of GLDH and DHAR genes were highest at 20 days after full bloom (DAFB) and then decreased to their minimum at harvest. When the fruit were grown in the dark induced by bagging, the ascorbate contents, enzyme activities and gene expression amounts had a statistical decline compared to the control in the most sampling dates. However, although L-AsA metabolism was affected and the use of light transmitting fruit bags may be preferable, the drop in vitamin C was not really significant in a dietary sense.

中文翻译：

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套袋对梨果实抗坏血酸的影响

摘要 在这里，在树上发育过程中，研究了 Pyrus pyrifolia 'Cuiguan' 袋装和未袋装果实中 L-抗坏血酸 (AsA) 的含量以及 AsA 生物合成中酶和基因的活性。AsA/脱氢抗坏血酸（DHA）和谷胱甘肽（γ-谷氨酰-L-半胱氨酰甘氨酸，GSH）/氧化型谷胱甘肽（GSSG）对的含量，L-半乳糖-1,4-内酯脱氢酶（GLDH；EC 1.3）的酶活性。 2.3)、L-半乳糖脱氢酶（GalDH；EC 1.1.1.117）、抗坏血酸过氧化物酶（APX；EC 1.11.1.11）、单脱氢抗坏血酸还原酶（MDHAR；EC 1.6.5.4）、谷胱甘肽依赖性脱氢抗坏血酸脱氢酶（EC 1.18.5.18 ) 和谷胱甘肽还原酶 (GR; EC 1.6.4.2)，GLDH 和 DHAR 基因的相对表达水平在盛开后 20 天 (DAFB) 最高，然后在收获时降至最低。套袋诱导的黑暗中生长的果实，在大多数采样日期，抗坏血酸含量、酶活性和基因表达量与对照相比均有统计学下降。然而，尽管 L-AsA 代谢受到影响并且使用透光水果袋可能更可取，但维生素 C 的下降在饮食意义上并不显着。