Integrating roots into a whole plant network of flowering time genes in Arabidopsis thaliana
Molecular data concerning the involvement of the roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of root transcriptome in Arabidopsis in order to identify flowering time genes that are expressed in the roots and genes that are differentially expressed in the roots during the induction of flowering. Data mining of public microarray experiments uncovered that about 200 genes whose mutation was reported to alter flowering time are expressed in the roots but only few flowering integrators were found. Transcriptomic analysis of the roots during synchronized induction of flowering by a single 22 h long day revealed that 595 genes were differentially expressed. A delay in clock gene expression was observed upon extension of the photoperiod. Enrichment analyses of differentially expressed genes in root tissues, gene ontology categories and cis regulatory elements converged towards sugar signaling. We inferred that roots are integrated in systemic signaling whereby carbon supply coordinates growth at the whole plant level during the induction of flowering.