Ascorbic Acid Accumulation and Expression of Genes Involved in Its Biosynthesis and Recycling in Developing Apple Fruit

作者:Li, Mingjun; Chen, Xuesen; Wang, Pingping; Ma, Fengwang*
来源:Journal of the American Society for Horticultural Science, 2011, 136(4): 231-238.
DOI:10.21273/JASHS.136.4.231

摘要

The objective of this study was to investigate ascorbic acid (AsA) accumulation, mRNA expression of genes involved in AsA biosynthesis as well as recycling, activity of key enzymes, and the relationship of them to AsA levels during the development of apple fruit (Malus x domestica cv. Gala). AsA concentration, which mainly depends on biosynthesis, was the highest in young fruit post-anthesis and then decreased steadily toward maturation. However, AsA continued to accumulate over time because of the increase in fruit mass. Transcript levels of guanosine diphosphate (GDP)-L-galactose phosphorylase, GDP-mannose pyrophosphorylase, D-galacturonate reductase, and the post-transcriptionally regulated L-galactono-1,4-lactone dehydrogenase were not correlated with AsA accumulation in apple. In contrast, patterns of expression for L-galactose dehydrogenase, L-galactose-1 -phosphate phosphatase, and GDP-mannose-.3',5'-epimerase showed a pattern of change similar to that of AsA accumulation. Although activities and expression levels of monodehydroascorbate reductase and dehydroascorbate reductase in fruit, which had less capacity for AsA recycling, were much lower than in leaves, they were not clearly correlated with AsA level during fruit development.