Open Field Trial of Genetically Modified Parthenocarpic Tomato: Seedlessness and Fruit Quality - Genetic Engineering: Recent Developments in Applications - page 152

Parthenocarpic fruits have been produced by traditional breeding methods
based either on mutant lines or other strategies such as alteration of the ploidy
level as in banana and watermelon [2]. However, genetic parthenocarpy has been
used only for a limited number of species and varieties. In some species and vari-
eties, seedless fruit production is often achieved by external application of plant
growth regulators as in the case of grape, tomato and eggplant [3].
Several methods to genetically engineer parthenocarpic fruit development
have been proposed, and some have also been tested experimentally in crop plants
[1,2]. Thus, transgenic parthenocarpic plants have been obtained for horticultural
crops [4-7]. In particular, the chimeric gene DefH9-iaaM has been used to drive
parthenocarpic fruit development in several species belonging to different plant
families [4,5,7]. The DefH9-iaaM transgene promotes the synthesis of auxin
(IAA) specifically in the placenta, ovules and tissues derived therefrom [4,8]. The
agronomical advantages of DefH9-iaaM GM plants have been assessed by green-
house and field trials of DefH9-iaaM eggplant [9,10], strawberry and raspberry [7].
Figure 1. Mean weekly values of maximum and average temperatures from 14 May until 27 August 2003.
The DefH9-RI-iaaM gene construct produces high quality parthenocarpic
fruits in the tomato cultivar UC 82, a variety used by the processing industry. The
DefH9-iaaM gene construct gave rise to malformed parthenocarpic fruits because
of high sensitivity to auxin that is present in the UC 82 genetic background [8].