9500360 Dunsmuir Flavor in tomato fruit is associated with high levels of both sugars and acids. It is known that the level of malic acid in the fruit declines by 50 per cent with ripening and this reduction is thought to be mediated by cytosolic NADP-malic enzyme (NADP-ME). This project will attempt to specifically decrease the levels of the NADP-ME in the tomato fruit using targeted gene suppression. A number of transgenic tomato lines will be generated with diminished levels of the fruit-specific NADP-ME and the biochemical and sensory properties of these lines will be examined. Transgenic lines which are identified as having elevated malic acid levels in the ripe fruit and improved sensory properties, will then be evaluated in the field to determine whether there are any deleterious agronomic effects and to identify suppressed lines which would be used in breeding programs. The anticipated outcome of this research is the ability to directly engineer the acid levels in tomato fruit which could significantly effect the flavor of tomatoes and could result in the development of a technical approach for the directed alteration of acid levels in fruit such as tomatoes, grapes and pineapples. This could improve flavor for fresh market and processed fruits.
