Transcriptomic Analysis at Organ and Time Scale Reveals Gene Regulatory Networks Controlling the Sulfate Starvation Response of Solanum Lycopersicum.

Abstract

Background: Sulfur (S) is a major component of biological molecules and thus an essential element for plants. Although the biochemistry and metabolism of sulfate is well understood, little is known about the regulatory mechanisms underlying plant responses to sulfate deprivation, especially in crop plants such as tomato (Solanum lycopersicum). In this work we analyzed the impact of sulfate starvation on the transcriptome of tomato plants to identify regulatory networks and key transcriptional regulators at a temporal and organ scale. Results: Sulfate starvation reduces the growth of roots and leaves which is accompanied by major changes in the organ transcriptome, with the response being temporally earlier in roots than leaves. Comparative analysis showed that a major part of the Arabidopsis and tomato transcriptomic response to sulfate starvation is conserved between these plants and allowed for the identification of processes specifically regulated in tomato, including the control of internal phosphate levels. Integrative gene network analysis uncovered key transcription factors controlling the temporal expression of genes involved in sulfate assimilation, as well as cell cycle, cell division and photosynthesis during sulfate starvation in tomato roots and leaves. Interestingly, one of these transcription factors presents a high identity with SLIM1, a central component of the sulfate starvation response in Arabidopsis. Conclusions: Together, our results provide the first comprehensive catalog of sulfate-responsive genes in tomato, as well as novel regulatory targets for future functional analyses in tomato and other crops.