cDNA microarray analysis of developing vitis vinifera cv shiraz berry skin

Microarray analysis of grape berry skin development was undertaken using RNA derived from flowers, 2 week post flowering whole berries, week 5, week 8, week 10 (veráison, green berries), week 12 and week 13 berry skin in addition to a comparison of RNA expression in pigmented and unpigmented berry skin at veráison (week 10). Image and statistical analysis revealed four sets of genes with distinctive and similar expression profiles over the course of berry development. The first set was composed of genes which had maximum RNA expression in flowers followed by a steady decrease in expression. The most prominent group within this set were genes which have a role in photosynthesis. The second set of cDNAs were dominated by genes involved in flavonoid biosynthesis and had a peak of expression week two post flowering. The data clearly illustrates co-ordinate regulation of flavonoid biosynthetic genes which code for the enzymes 4-coumarate-CoA ligase, chalcone synthase, chalcone isomerase, flavonone hydroxylase, anthocyanidin reductase and cytochrome b5. The third set of cDNAs were those that exhibited maximum expression week 5 post flowering, midway between flowering and veráison, a period of rapid berry growth. This set of cDNAs is dominated by genes which code for structural cell wall proteins. The fourth set of genes were dramatically upregulated at veráison and remain upregulated until 13 weeks post flowering and is composed of a diverse range of genes, a reflection of complexity, most with no known function indicating ripening requires the activity of genes unique to this process.