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First published online March 26, 2004; 10.1104/pp.103.031971 Plant Physiology 134:1574-1585 (2004) © 2004 American Society of Plant Biologists
Regulation of Flower Development in Arabidopsis by SCF Complexes1Department of Biology and the Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802 (W.N., B.F., D.Z., J.A., H.M.); Institute of Molecular and Cell Biology, Singapore 11609 (D.X.); and Department of Biology, Adelphi University, Garden City, New York 11530 (L.H.)
SCF complexes are the largest and best studied family of E3 ubiquitin protein ligases that facilitate the ubiquitylation of proteins targeted for degradation. The SCF core components Skp1, Cul1, and Rbx1 serve in multiple SCF complexes involving different substrate-specific F-box proteins that are involved in diverse processes including cell cycle and development. In Arabidopsis, mutations in the F-box gene UNUSUAL FLORAL ORGANS (UFO) result in a number of defects in flower development. However, functions of the core components Cul1 and Rbx1 in flower development are poorly understood. In this study we analyzed floral phenotypes caused by altering function of Cul1 or Rbx1, as well as the effects of mutations in ASK1 and ASK2. Plants homozygous for a point mutation in the AtCUL1 gene showed reduced floral organ number and several defects in each of the four whorls. Similarly, plants with reduced AtRbx1 expression due to RNA interference also exhibited floral morphological defects. In addition, compared to the ask1 mutant, plants homozygous for ask1 and heterozygous for ask2 displayed enhanced reduction of B function, as well as other novel defects of flower development, including carpelloid sepals and an inhibition of petal development. Genetic analyses demonstrate that AGAMOUS (AG) is required for the novel phenotypes observed in the first and second whorls. Furthermore, the genetic interaction between UFO and AtCUL1 supports the idea that UFO regulates multiple aspects of flower development as a part of SCF complexes. These results suggest that SCF complexes regulate several aspects of floral development in Arabidopsis.
1 This work was supported by the National Science Foundation (grant nos. MCB9896340 and MCB0092075 to H.M. and IBN998926 to L.H.), and by funds from the Department of Biology and the Huck Institutes of Life Sciences at the Pennsylvania State University. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.031971. * Corresponding author; e-mail hxm16{at}psu.edu; fax 8148631357. Received August 19, 2003; returned for revision November 3, 2003; accepted January 12, 2004. This article has been cited by other articles:
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