《植物生理学报》 2016, 52(12): 1877-1883

不同基因型猕猴桃果实中抗坏血酸合成与代谢的差异

原玉林, 同晓蕾, 侯长明, 马锋旺, 李明军^*

西北农林科技大学园艺学院, 陕西杨凌712100

通信作者：李明军；E-mail: limingjun@nwsuaf.edu.cn

摘　要：

植物中的抗坏血酸(ascorbic acid, AsA)不仅与植物自身生长发育和抗逆性有关, 而且是人类主要的Vc来源。为了探究不同基因型猕猴桃AsA含量差异机制, 本研究以AsA含量差异较大的8个基因型猕猴桃果实为材料, 测定比较了它们AsA及其代谢物的含量, 分析了关键合成酶L-半乳糖1, 4-内酯脱氢酶(GalLDH)及代谢酶活性与AsA含量的关系。结果表明, 不同基因型猕猴桃果实中AsA和AsA相关代谢物水平存在明显的多样性。总抗坏血酸(T-AsA)含量与AsA/DHA存在显著的相关性, 而与还原型谷胱甘肽(GSH)、草酸(OA)及酒石酸(TA)含量之间无显著相关性。此外, T-AsA合成代谢酶GalLDH及AsA–GSH循环系统相关酶活性在不同基因型猕猴桃中也存在较大差异。其中GalLDH、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDHAR)的活性均与AsA含量存在极显著相关性, 并且MDHAR活性分别与AsA含量和抗坏血酸过氧化酶(APX)都有较高的相关性。

关键词：抗坏血酸; AsA–GSH循环; 猕猴桃; 酶活性

收稿：2016-07-08   修定：2016-10-20

资助：陕西省科技统筹创新工程计划(2012KTJD03-01)。

Difference of ascorbic acid synthesis and metabolism in different genotypes of kiwifruit

YUAN Yu-Lin, TONG Xiao-Lei, HOU Chang-Ming, MA Feng-Wang, LI Ming-Jun^*

College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China

Corresponding author: LI Ming-Jun; E-mail: limingjun@nwsuaf.edu.cn

Abstract:

Ascorbic acid (AsA) in plants is not only related to its development, growth and stress resistance, but also a main source of vitamin C (Vc) for human. To investigate the mechanisms of AsA concentration difference in the genotypes of kiwifruit, eight genotypes of kiwifruit were used to analyze the relationships between AsA concentration and enzyme activities involved in its biosynthesis (L-galactose-1,4-lactone dehydrogenase, GalLDH) and recycle in fruit. The results indicated that, the levels of AsA and AsA-related metabolites in fruit showed distinct diversity among eight genotypes. Total AsA (T-AsA) concentration showed significant correlation with AsA/DHA ratio, but not with glutathione (GSH), oxalic acid (OA) and tartaric acid (TA). Besides, the activities of T-AsA synthase GalLDH and related enzymes in ascorbate–glutathione (AsA–GSH) recycle system were also significantly different in different genotypes of kiwifruit. The activities of GalLDH, monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) showed extremely significant correlation with AsA concentration, and MDHAR activity had higher correlationships with AsA concentration and ascorbate peroxidase (APX) respectively.

Key words: ascorbate; AsA–GSH recycle; kiwifruit; enzyme activity