Expression profiles of genes and enzymes related to ascorbic acid metabolism in fruits of Ziziphus jujuba Mill. &amp;lsquo;Jinsixiaozao&amp;rsquo;

Jin Zhao,Mengjun Liu,Yingying Chen,Zhihui Zhao

doi:10.15302/j-fase-2016096

Abstract

The fruit of Chinese jujube (Ziziphus jujuba) possesses extremely high concentrations of ascorbic acid (AsA). The accumulation of AsA, the expression patterns of the nine genes related to AsA metabolism as well as the activities of five enzymes involved in AsA synthesis, oxidation and recycling were investigated during fruit development in Z. jujuba Mill. 'Jinsixiaozao'. The results showed that the high level of AsA accumulation in jujube fruit is due to a contribution from both AsA biosynthesis and AsA recycling. It is suggested that L-galactono-1,4- lactone dehydrogenase, ascorbate peroxidase and mono- dehydro-ascorbate reductase are the crucial genes/ enzymes of jujube AsA synthesis, oxidization and recycling, respectively. These results provide useful new insights into the regulatory mechanisms of AsA accumu- lation in Chinese jujube.

Highlights

Ascorbic acid (AsA), named as ascorbate or vitamin C, is an essential metabolite for both plants and animals
Eight genes related to ascorbic acid (AsA) metabolism were isolated by homologous gene cloning methods using the relevant data from the jujube genome, i.e., GDP-D-mannose pyrophosphorylase (ZjGMP, accession number KJ934995), GDP-mannose 3′,5′-epimerase (ZjGME), GDP-L-galactose phosphorylase (ZjGGP); L-galactose-1-P phosphatase (ZjGPP, accession number KJ739593), L-galactose dehydrogenase (ZjGLDH), ascorbate oxidase (ZjAO), dehydroascorbate reductase (ZjDHAR), and monodehydroascorbate reductase (ZjMDHAR)
These genes belong to three groups, synthetic genes (GMP, GME, GGP, GPP, GLDH), oxidic genes (MDHAR, DHAR) and recycling genes (APX, AO)

Summary

Introduction

Ascorbic acid (AsA), named as ascorbate or vitamin C, is an essential metabolite for both plants and animals. AsA is involved in expansion, division and enlargement of cells, promoting the formation of apical meristem, regulating flowering, fruit development and senescence and many other physiological processes[1,2,3,4,5]. It is an effective radical scavenger that is able to interact with the reactive oxygen species[6]. Mill.), one of the native and main fruit species of China, is an outstanding source of AsA. The AsA concentration of jujube fruit is a few dozen times that of other common fruit and even higher than kiwifruit[7] and understanding the mechanism underlying the high accumulation of AsA in Chinese jujube is important

Methods

Results

Discussion

Conclusion