Increasing tomato fruit quality by enhancing fruit chloroplast function. A double-edged sword?

Fruits are generally regarded as photosynthate sinks as they rely on energy provided by sugars transported from leaves to carry out the highly demanding processes of development and ripening; eventually these imported photosynthates also contribute to the fruit organoleptic properties. Three recent reports have revealed, however, that transcriptional factors enhancing chloroplast development in fruit may result in higher contents not only of tomato fruit-specialized metabolites but also of sugars. In addition to suggesting new ways to improve fruit quality by fortifying fruit chloroplasts and plastids, these results prompted us to re-evaluate the importance of the contribution of chloroplasts/photosynthesis to fruit development and ripening.