Identification of loci affecting flavour volatile emissions in tomato fruits

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Abstract
Fresh tomato fruit flavour is the sum of the interaction between sugars, acids, and a set of approximately 30 volatile compounds synthesized from a diverse set of precursors, including amino acids, lipids, and carotenoids. Some of these volatiles impart desirable qualities while others are negatively perceived. As a first step to identify the genes responsible for the synthesis of flavour-related chemicals, an attempt was made to identify loci that influence the chemical composition of ripe fruits. A genetically diverse but well-defined Solanum pennellii IL population was used. Because S. pennellii is a small green-fruited species, this population exhibits great biochemical diversity and is a rich source of genes affecting both fruit development and chemical composition. This population was used to identify multiple loci affecting the composition of chemicals related to flavour. Twenty-five loci were identified that are significantly altered in one or more of 23 different volatiles and four were altered in citric acid content. It was further shown that emissions of carotenoid-derived volatiles were directly correlated with the fruit carotenoid content. Linked molecular markers should be useful for breeding programmes aimed at improving fruit flavour. In the longer term, the genes responsible for controlling the levels of these chemicals will be important tools for understanding the complex interactions that ultimately integrate to provide the unique flavour of a tomato.