Abstract
Lateral floral clusters were removed from the main axis of the floral clusters of ‘Houman’ grape plants, leaving only 3–5-cm-long region of flowers at the end of the central axis. The floral clusters were pruned at 7 days prior to flowering. The effect of the pruning on fruit quality was assessed by determining the composition and levels of anthocyanins in the fruit and anthocyanin-related gene expression. Results indicated that floral cluster pruning significantly improved the quality of the fruit by increasing berry size, fruit weight and the total content of soluble solids. Floral cluster pruning also decreased the level of titratable acidity. Sixteen different anthocyanins were detected in fruit of the pruned clusters, while only 15 were detected in fruit from unpruned clusters. The level of anthocyanins was also significantly higher in fruit of the pruned clusters than in the unpruned clusters. Anthocyanin-related gene expression was also significantly upregulated to a higher level in fruit from pruned floral clusters as compared with unpruned clusters. The upregulation was closely associated with increases in anthocyanin biosynthesis.
Highlights
Anthocyanins are important, red, blue, purple and purple-black plant pigments that are widely distributed in the cell vacuoles of flowers, fruits, roots, stems and leaves.[1,2] Grape anthocyanins are mainly found in the skin of mature fruits
The genes involved in anthocyanin biosynthesis may be divided into two categories: structural genes, which are directly involved in anthocyanin biosynthesis,[3] and regulatory genes such as MYB and bHLH that are not directly involved in anthocyanin synthesis but rather regulate the expression of anthocyanin structural genes.[4,5,6]
The average weight of berries obtained from fruit clusters subjected to floral cluster pruning was 11.53 g, which was 1.2 times greater than berries from unpruned floral clusters (Figure 1b)
Summary
Anthocyanins are important, red, blue, purple and purple-black plant pigments that are widely distributed in the cell vacuoles of flowers, fruits, roots, stems and leaves.[1,2] Grape anthocyanins are mainly found in the skin of mature fruits. The degree and timing of fruit coloring depends on the type and level of anthocyanins that are synthesized. Skin color in grapes is an important index for evaluating fruit appearance and market value, and its importance to market prices has been gradually increasing. The interaction between the genotype, environment and management practices heavily influence the overall composition and levels of produced anthocyanins
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