CONSTANS and jasmonate signaling coordinate floral senescence in Arabidopsis

Photoperiodic floral initiation in the leaf is controlled by the hub gene CONSTANS (CO) while jasmonates (JAs) control flower senescence. Although both processes are chronologically ordered, no association between them has been described to date. We show that CO protein remains in Arabidopsis flowers after the floral induction, although displaying a different tissue and diurnal pattern than in leaves. We found that changes in CO expression alter flower senescence and abscission by interfering with the JA response, supported by petal specific analysis as well as CO overexpression in JA synthesis and signaling mutants. CO has a ZIM-like domain that mediates interaction with the JA response repressor JAZ3 (jasmonate ZIM-domain 3), inhibiting its repressor activity and activating downstream transcription factors involved in flower senescence. The complex CO-JAZ3 also interacts with the E3 ubiquitin ligase Coronatine Insensitive 1 (COI1) leading to its degradation in the presence of jasmonates. Therefore, the coordinated recruitment of photoperiodic and jasmonate signaling pathways would be an efficient way for plants to chronologically order the floral process and ensure the success of offspring production. Overall design: Comparative gene expression profiling analysis of RNA-seq data for seedlings and petals of Col-0 (WT), 35S:CO (CO overexpressor) vs co-10 (CO null mutant) Arabidopsis thaliana plants.