Role of WIP transcription factors in male flower formation

An integrative genome-wide analysis reveals role of WIP transcription factors in male flower formation

Flowers are the reproductive organs of angiosperms. The production of unisexual flowers and plants is instrumental in plant breeding, as they ease the production of F1 hybrid seeds. In the group FLOCAD at the IPS2 (http://www.ips2.universite-paris-saclay.fr/en/research/dgg-department-developmental-genomics-and-genetics/flocad-developpement-floral-et-determinisme-du-sexe.html), the CmWIP1 gene was previously identified as master regulator of sex determination in cucurbits. To bring new insight in the function of CmWIP1, Gomez Roldan, Izhaq et al. (https://www.nature.com/articles/s42003-020-0969-2) investigated two Arabidopsis WIP transcription factors, AtWIP1/TT1 and AtWIP2/NTT. Using an inducible system, they showed that WIPs are powerful inhibitor of growth and inducer of cell death. Combination of ChIP-seq and RNA-seq data revealed that most of the up-regulated genes bound by WIPs display a W-box motif, associated with stress signaling. In contrast, the down-regulated genes contain a GAGA motif, a known target of Polycomb-repressive complex. To validate the role of WIP proteins in inhibition of growth, AtWIP1/TT1 was expressed in carpel primordia and only male flowers were obtained, mimicking the function of CmWIP1 in melon. Using other promoters, authors further demonstrated that WIPs can trigger growth arrest of both vegetative and reproductive organs. These data supports an evolutionary conserved role of WIPs in recruiting gene networks controlling growth and adaptation to stress. The use of WIP proteins as a biotechnology tool to engineer male or female plants in other species is proposed.

Arabidopsis flowers of Wild-Type (a) and transgenic plants expressing AtWIP1/TT1 under the control of the CRC promoter (b), specific to the carpel primordium. (c) Schematic model of how WIPs control growth