Field trials of genetically modified tomato: fruit quality and productivity.

In the past twenty years, plant genetic engineering has been used to confer traits of both heuristic and applied interest to tomato. Genetic modifications have aimed to improve either the quality of the fruit and/or agronomical aspects of tomato cultivation. In open field trials, the novel genotype is tested under agronomical and environmental conditions similar to those used for production. Thus, field trials represent the most stringent test for any novel plant genotype, including genetically modified plants. In the following article, we discuss field trials performed with transgenic tomato plants that represent examples of different genetic strategies used in modern plant breeding. The examples chosen are genetic modifications related to three general aspects: (1) macro- and micro-nutrient content of the fruit, such as sugar content and beta-carotene content, (2) biological processes of either direct or indirect agronomical interest, such as parthenocarpy and resistance to disease, (3) features related to post-harvest and processing technology, such as fruit firmness and prolonged fruit vine-life. The discussion is focused on three main aspects: the genetic strategy used to confer the novel phenotypic trait(s), quality assessment of the genetically modified plant and fruit, and plant production. The results obtained confirm the value of plant genetic engineering as a means of improving tomato productivity and tomato products.