Plant growth and the TOR pathway.

In mammalian, insect, and yeast cells, TOR proteins are essential regulators of cell growth in response to environmental signals including nutrients, mitogens, and stresses. Although many aspects of the TOR-dependent signalling pathway are conserved between animals and fungi, important differences have also been found and are likely to be related to the ecophysiological adaptations of these organisms. The TOR protein also exists in plants. This review will first discuss specific aspects of plants concerning the contribution of cell growth to overall growth, as well as their responses to nutrient starvation, with emphasis on recent results obtained through genetic analysis in the model plant Arabidopsis thaliana. This is followed by the current status of the genetic analysis of the TOR gene in this plant and the search for potential members of a TOR pathway in the Arabidopsis genome.