College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, PR China.
Horticultural Sciences Department, IFAS, University of Florida, Gainesville, FL, 32611-0690, USA.
Plant Physiol Biochem. 2018 Mar;124:20-28. doi: 10.1016/j.plaphy.2018.01.005. Epub 2018 Jan 6.
Kiwifruit (Actinidia eriantha Benth.) 'White', a novel cultivar with higher L-ascorbic acid (AsA) level, is registered in China. Changes in AsA, related metabolites, enzymatic activity, and gene expression associated with AsA biosynthesis and recycling process were investigated in this paper. The results indicated that AsA biosynthesis through L-galactose pathway supplemented by D-galacturonic acid pathway and AsA recycling collectively contributed to accumulating and remaining higher AsA level in kiwifruit cv. 'White' during postharvest. Moreover, L-galactose dehydrogenase (GalDH) activity and relative expressions of the genes encoding GDP-D-mannose pyrophosphorylase (GMP), L-galactose-1-P phosphatase (GPP), GDP-L-galactose phosphorylase (GGP), GalDH and D-galacturonate reductase (GalUR) were important for regulation of AsA biosynthesis, and the activity and expression of dehydroascorbate reductase (DHAR) were primarily responsible for regulation of AsA recycling in kiwifruit 'White' during postharvest.
“白肉”猕猴桃（Actinidia eriantha Benth.）是一个新型品种，具有更高的 L-抗坏血酸（AsA）水平，已在中国注册。本文研究了与 AsA 生物合成和循环过程相关的 AsA、相关代谢物、酶活性和基因表达的变化。结果表明，L-半乳糖途径与 D-半乳糖醛酸途径共同补充的 AsA 生物合成以及 AsA 再循环有助于在果实采后保持“白肉”猕猴桃中较高的 AsA 水平。此外，L-半乳糖脱氢酶（GalDH）活性和编码 GDP-D-甘露糖焦磷酸化酶（GMP）、L-半乳糖-1-P 磷酸酶（GPP）、GDP-L-半乳糖磷酸化酶（GGP）、GalDH 和 D-半乳糖酸还原酶（GalUR）的基因的相对表达水平对 AsA 生物合成的调节很重要，而果实采后“白肉”猕猴桃中脱氢抗坏血酸还原酶（DHAR）的活性和表达则主要负责调节 AsA 的再循环。
