Understanding and improving quality through a genomics approach

Abstract

The interaction between the vine, viticultural practices and the environment is a complex one in which changes in gene expression play a central part. The developmental program which ‘designs and runs’ berry growth and ripening is largely mediated through changes in gene expression. In addition many of the interactions that occur between the berry and the environment and which impact on berry characteristics are also reliant on changes in gene expression. We have used microarray technology, which allowed us to assess the expression of thousands of genes at once to develop maps of gene transcription to describe berry development and identify potential molecular markers for each stage of development. To relate gene expression data to berry development and composition as well as wine quality a holistic approach was taken. Sensory analysis was performed on the wine, and berry development and composition parameters i.e. berry weight, brix, sugars, anthocyanins, acids, inorganic elements and amino acids were measured throughout development. The microarray grape GeneChip used in these studies contained nearly 16000 gene features that represented between one third to one half of all the protein coding genes expected to be present in the grapevine genome. Our work showed that there are surprisingly frequent changes in the expression of many genes throughout berry development. Some of these changes, such as those associated with the initiation of ripening, appeared to be part of the plants inbuilt developmental program. Few significant gene expression changes were found when viticulture management treatments (irrigation or pruning) were compared. More numerous gene expression changes were found between berries from different sites suggesting that the expression of a group of genes within the berry are markedly influenced by environmental factors. By studying the changes in gene expression that occur in berries grown under different conditions we have developed a greater understanding of the key genes that control berry growth and berry composition and how they are regulated.

Summary

By linking data on berry gene expression with berry biochemical analysis and wine sensory studies we are completing the chain from gene to wine in an attempt to identify key genes that will provide indicators of the current berry state and predictors of fruit outcomes.