Résumé
Surprisingly, differences in phenotypes and gene expression are observed between genetically identical individuals 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 for unicellular organisms, it is still very scarce when it comes to variability between multicellular organisms. Using plants as a model we analysed the establishment, maintenance and consequences of inter-individual transcriptional variability. We showed, for a gene of interest, that differences in expression between plants are established in young seedlings, maintained over several days but not transmitted to the next generation. Our results also indicate that these differences in expression can explain phenotypic variability between plants such as for the root growth. Finally, using a genome-wide approach, we found a co-expression in seedlings for our gene of interest, involved in nitrate nutrition, and genes involved in photosynthesis. 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 of this state between plants, and then maintained over time.