Tomato plants expressing a stilbene synthase gene display genotype‐depending alterations in metabolome profile and antioxidant system

Abstract

AbstractIn the present work, we report a study on tomato Micro‐Tom lines expressing the Vitis vinifera StSy1 cDNA encoding stilbene synthase under the control of a CaMV 35S promoter. Transgenic lines (T1 plants) were evaluated in terms of vegetative and reproductive development, fruit production, the activity of the main antioxidant enzymes, and the metabolome profile in both leaves and fruit juices. Trans‐resveratrol and glycosylated derivates accumulated in some of the transgenic lines generated, the concentration of both compounds being higher in the leaves than in the fruit juices. Vegetative development was enhanced by transformation, whereas fruit production decreased, and fruit soluble solids content (°Bx) increased. Remarkably, trans‐resveratrol content in leaves and fruit juices showed no correlation with the expression levels of StSy1. An alteration of the metabolome profile and antioxidant enzyme activities was recorded in most of the transgenic lines. In tomato fruit juices, the variation between the wild type and transgenic lines was attributed to a major number of differentially expressed metabolites as compared to that observed in the leaves. In this sense, the major changes corresponded to an induction of phenylpropanoid pathway‐related compounds in the lines accumulating trans‐resveratrol. Transgenic lines producing resveratrol showed, overall, an imbalanced antioxidant metabolism characterized by higher superoxide dismutase (H2O2‐producing enzyme) activity and lower H2O2‐scavenging enzyme activities. This work contributes to deciphering the biochemical consequences of StSy1 introduction in tomato and opens up prospects for further characterization of the transformants.