Genetics of Pigment Biosynthesis and Degradation

Abstract

Within the genus Actinidia, there is large variability in fruit skin and flesh colour. The most familiar kiwifruit, A. chinensis var. deliciosa 'Hayward', has flesh of bright emerald green. Although many species have live, coloured fruit skins, most commercial cultivars have a dead, brown fruit skin. Hidden underneath the skin is a diversity and range of flesh colours which are characteristic of the species or specific genotypes. From a commercial point of view, flesh colour has become a particularly important feature which distinguishes the fruit and new cultivars in the market. In today's market, there is a large number of cultivars with a range of flesh colours grouped into three main categories: green, yellow and red. The red-fleshed cultivars are a recent addition and have generated great interest throughout the industry worldwide. It is also the distinctive feature of the genotype used to build the reference genome for A. chinensis var. chinensis (Huang et al., 2013). Fruit ColourAnthocyanins, carotenoids and chlorophylls are responsible for almost all fruit coloration. Plant breeding and domestication have produced numerous fruit where the levels and distribution of pigments vary widely, changing during development and in response to the environment. The accumulation of pigments in fruit is an important indicator of ripeness, quality and value. These pigments also differentiate cultivars for consumers, as well as being implicated in the health attributes of our foods. A highly pigmented fruit has become perceived by consumers as conferring

Dynamic Changes of Phenolic Compounds and Their Associated Gene Expression Profiles Occurring during Fruit Development and Ripening of the Donghong Kiwifruit

“…The red pigmentation of the Donghong kiwifruit accumulated in only a part of fruit pericarp (the inner pericarp) in Figure 1 is one typical phenotype of the red color in the fruit flesh of kiwifruit. 10,28,30 The most predominant colorless phenolic compound in the Donghong kiwifruit was epicatechin (Figure 2B), which was consistent with the findings reported by Ma et al, who demonstrated that the highest amount of epicatechin was found in the red-fleshed Hongyang cultivar. 9 Most previous studies focused on the phenolic constituents and content caused by kiwifruit varietal differences, 9,33 whereas the dynamic changes throughout fruit growth and development remain largely unexplored.…”

“…were always the core anthocyanidin components in kiwifruit. 10,29,30,42 Here, all investigated fruit samples were collected from plants received from identical horticultural practices under same pedoclimatic conditions. In addition, strictly identical extraction conditions and analytical parameters for all the samples were also carried out.…”

“…4,8 In general, the predominant classes of the phenolic fraction in kiwifruit are phenolic acids, flavonols (flavan-3-ols), flavanols, and anthocyanins. 9,10 Phenolic acids are substituted derivatives of hydroxycinnamic acids and hydroxybenzoic acids. 11 Scientific interest on phenolic acids has been attracted due to their immense dietary health benefits and functionalities.…”

Chlorophyll, carotenoid and vitamin C metabolism regulation in Actinidia chinensis 'Hongyang' outer pericarp during fruit development

“…deliciosa (green-fleshed) both contain about 2 μg carotenoids g -1 fresh weight, which generally remains stable in the fruit [ 2 ]. Carotenoid accumulation is a balance of continual biosynthesis and degradation [ 6 ]. Some carotenoid biosynthesis and degradation gene expression changes have been previously examined during kiwifruit maturation and softening ( S2 Fig ).…”