Dynamic Changes of Vitamin C in Actinidia deliciosa ‘Xuxiang’ During Fruit Development

Vitamin C was one of water-soluble vitamins. It could be obtained from most fruits and vegetables [1]. Unlike animals, human could not synthesis vitamin C in liver [2]. As we all known, vitamin C was a way to prevent scurvy. More recent studies showed that Vitamin C can be used in additional health benefits and the prevention other diseases such as hyperuricemia [3], melanoma [4]. Thus, vitamin C was a vital component of human diet and it was responsible for several body actions such as aiding in the reaction of key enzymes and redox reactions [5]. Inmost plants, vitamin C was known as a cofactor for enzymes and also plays a role in the regulation of genes involved in defense mechanism and signaling in hormone pathways.

Vitamin C biosynthesis in plants occurred through various routes but activation of each pathway was dependent upon species and developmental stages of the plant [6]. Vitamin C biosynthesis most used D-Glucose as main precursor in mitochondrion. The first route was promoted is L-galactose pathway in strawberry [6]. Later on, several studies have promoted other vitamin C biosynthesis routes, which was L-gulose, the myoinositol and D-galacturonic acid pathways as well as ascorbate– glutathione cycle [7]. Additionally, L-galactose pathway was considered to be one of significant pathways, although other routes were also existed [8].

Kiwifruit (Actinidia spp.), an economically important crop, was cultivated worldwide. Kiwifruit was native to China, which included A. chinensis, A. deliciosa and a small amount of A. arguta. Kiwifruit was a valuable fruit with characteristic taste and flavor and high vitamin C contents. Before, fruit producers mainly paid attention on fruit yield, appearance, size and quality. In recent years, consumers have been more and more increasing concerned about the nutritional value such as Vitamin C.

To date no studies have investigated formation and accumulation mechanism on vitamin C of ‘Xuxiang’ kiwifruit. The main objective was to analysis the correlation with Vitamin C contents and genes involved in L-galactose pathway and ascorbate– glutathione cycle. Via the correlation analysis, the key genes possibly close related to vitamin C accumulation would be discovered. Other objectives of this study were to discover the fruit traits change rules in terms of fresh weight, TSS, titratable acid, total sugar, Vitamin C and organic acid content.