Impacts of the overexpression of a tomato translationally controlled tumor protein (TCTP) in tobacco revealed by phenotypic and transcriptomic analysis.

KEY MESSAGE: Overexpression of a tomato TCTP impacts plant biomass production and performance under stress. These phenotypic alterations were associated with the up-regulation of genes mainly related to photosynthesis, fatty acid metabolism and water transport. The translationally controlled tumor protein (TCTP) is a multifaceted and highly conserved eukaryotic protein. In plants, despite the existence of functional data implicating this protein in cell proliferation and growth, the detailed physiological roles of many plant TCTPs remain poorly understood. Here we focused on a yet uncharacterized TCTP from tomato (SlTCTP). We show that, when overexpressed in tobacco, SlTCTP may promote plant biomass production and affect performance under salt and osmotic stress. Transcriptomic analysis of the transgenic plants revealed the up-regulation of genes mainly related to photosynthesis, fatty acid metabolism and water transport. This induced photosynthetic gene expression was paralleled by an increase in the photosynthetic rate and stomatal conductance of the transgenic plants. Moreover, the transcriptional modulation of genes involved in ABA-mediated regulation of stomatal movement was detected. On the other hand, genes playing a pivotal role in ethylene biosynthesis were found to be down-regulated in the transgenic lines, thus suggesting deregulated ethylene accumulation in these plants. Overall, these results point to a role of TCTP in photosynthesis and hormone signaling.