Our response to the odors of an excellent dinner reminds us that the enjoyment of food encompasses its aroma as well as its taste, texture, and appearance. Efforts to improve the tomato have focused on flavor and fruit stability, sometimes to the detriment of its aroma. Lewinsohn et al. have used metabolic engineering to augment the panoply of endogenous volatiles, comprising many organics, often present only in trace quantities. The monoterpene linalool is present in edible fruits (guava, peach, and plum) and also contributes to the aroma of several herbs (coriander and sweet basil).
Working with two lines of commercially available tomatoes, both of which lack linalool, the authors produced transgenic lines by adding a linalool synthase gene taken from the flowering plant Clarkia breweri. The tomato promoter selected to regulate the exogenous gene was one normally activated during ripening, hence the amount of linalool increased as the tomatoes changed from green to red. The altered profile of organics in the transgenic tomatoes was detectable by human noses, but the results of the taste test are not yet in. -- PJH
Plant Physiol. 127, 1256 (2001).
