Establishment, maintenance and consequences of inter-individual transcriptional variability for a gene involved in nitrate nutrition in plants

Differences in phenotypes and gene expression are observed between genetically identical plants grown in the same environment. While we now have a good knowledge of the source and consequences of transcriptional differences observed between cells, in particular in unicellular organisms, it is still very scarce when it comes to variability between multicellular organisms. Using NRT2.1, a high affinity nitrate transporter gene, as a model for high inter-individual transcriptional variability, we showed that differences in expression between plants for that gene are established in young seedlings, maintained over time but not transmitted to the next generation. Our results also indicate that these differences in expression could have phenotypic consequences. Indeed, they can explain phenotypic variability for the root growth as well as the amount of nitrate imported by the NRT2.1 protein in the plant. Finally, we found an enrichment for genes involved in photosynthesis among the ones with an expression correlated with NRT2.1 in single seedlings. All in all, our study suggests that a global coordination of the genes involved in the carbon/nitrate balance in plants is established in young seedlings, with differences in this state between plants, and then maintained over time.