Amino acid metabolism and accumulation in ‘Sauvignon Blanc’ grapes : Investigating berry composition in response to canopy manipulation

Amino acids are important compounds that occupy a pivotal position in grapevine metabolism and play a major role in the biological functions of fermentative microbes. The biochemical composition of the grape berry can be hugely varied and is the major determinant of wine quality through yeast growth and flavour/aroma metabolism. Manipulation of grapevine nutrition and viticultural management such as canopy manipulations, can directly influence grape berry biochemical composition. To advance our understanding of mechanisms involved in amino acid accumulation in Sauvignon blanc grapes, we performed preveraison and postveraison leaf removal experiments and quantified total and individual amino acids at multiple timepoints through development. Removing leaves from around the fruiting zone significantly reduced total amino acid accumulation in berries. Two amino acids in particular, arginine and proline, accumulate to high levels and make up the highest proportion of total amino acid concentrations at harvest. Both of these amino acids were significantly decreased by leaf removal. Conversely, berry phenology (°Brix and berry weight) was unaffected in our experiments and suggests that other regions of the grapevine canopy can compensate for the loss of a proximal leaf source. Results indicate that this compensation is not observed with respect to amino acid accumulation