Spatial distribution of the RABBIT EARS protein and effects of its ectopic expression in Arabidopsis thaliana flowers
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In many flowering plants, flowers consist of two peripheral organs, sepals and petals, occurring in outer two whorls, and two inner reproductive organs, stamens and carpels. These organs are arranged in a concentric pattern in a floral meristem, and the organ identity is established by the combined action of floral homeotic genes expressed along the whorls. Floral organ primordia arise at fixed positions in the floral meristem within each whorl. The RABBIT EARS (RBE) gene is transcribed in the petal precursor cells and primordia, and regulates petal initiation and early growth in Arabidopsis thaliana. We investigated the spatial and temporal expression pattern of a RBE protein fused to the green fluorescent protein (GFP). Expression of the GFP:RBE fusion gene under the RBE cis-regulatory genomic fragment rescues the rbe petal defects, indicating that the fusion protein is functional. The GFP signal is located to the cells where RBE is transcribed, suggesting that RBE function is cell-autonomous. Ectopic expression of GFP:RBE under the APETALA1 promoter causes the homeotic conversion of floral organs, resulting in sterile flowers. In these plants, the class B homeotic genes APETALA3 and PISTILLATA are down-regulated, suggesting that the restriction of the RBE expression to the petal precursor cells is crucial for flower development.
KeywordsAPETALA1 APETALA3 Floral organ Homeotic genes Petal PISTILLATA
Cleaved amplified polymorphic sequences
GREEN FLUORESCENT PROTEIN
We thank Mitsuhiro Aida, Takehide Kato (NAIST, Japan), Tetsu Kinoshita (Nagahama Institute of Bio-Science and Technology, Japan), Mie Ichikawa, Masahiko Sato, Takashi Shiina (Kyoto Prefectural University, Japan), and Kiyotaka Okada (NIBB, Japan) for providing materials and helpful discussion, and Rebecca Horn for critical reading of the manuscript. This research was supported by Japan Advanced Plant Science Network and funded by JSPS KAKENHI grant number 22570042 (S.T.).
Conflict of interest
The authors declare that they have no conflict of interest.
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