Robustness of organ morphology is associated with modules of co-expressed genes related to plant cell wall
Résumé
Reproducibility in organ size and shape is a fundamental trait of living organisms. The
mechanisms underlying such robustness remain, however, to be elucidated. Taking the sepal of
Arabidopsis as a model, we investigated whether variability of gene expression plays a role in
variation of organ morphology. To address this question, we produced a dataset composed of
both transcriptomic and morphological information obtained from 27 individual sepals from
wild-type plants. Although nearly identical in their genetic background, environment, and
developmental stage, these sepals exhibited appreciable variability in both morphology and
transcriptome. We identified modules of co-expressed genes in sepals, three of which
correlated significantly with morphology, revealing biologically relevant gene regulatory
networks. Interestingly, cell-wall related genes were overrepresented in two of these three
modules. Additionally, we found that highly variable genes were unexpectedly enriched in
cell-wall related processes. We then analyzed sepal morphology from 16 cell-wall mutants and
found that the more a gene is expressed in wild-type, the more variable the morphology of the
corresponding mutant. Altogether, our work unravels the contribution of cell-wall related genes
to the robustness of sepal morphology. More generally, we propose that canalizing traits during
development could rely on the modulation of highly expressed genes.
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