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First published online September 29, 2006; 10.1104/pp.106.086736 Plant Physiology 142:1039-1052 (2006) © 2006 American Society of Plant Biologists The FLORAL ORGAN NUMBER4 Gene Encoding a Putative Ortholog of Arabidopsis CLAVATA3 Regulates Apical Meristem Size in Rice1,[W]Shanghai Jiaotong University, Shanghai Institutes for Biological Sciences, Pennsylvania State University Joint Center for Life Sciences, Key Laboratory of Microbial Metabolism, Ministry of Education, School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200240, China (H.C., W.L., C.Y., H.T., X.Y., Z.Y., D.L., H.M., D.Z.); State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China (Q.Q.); Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.Y., H.H., D.L., H.M., D.Z.); and Department of Biology, the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 (H.M.)
To understand the molecular mechanism regulating meristem development in the monocot rice (Oryza sativa), we describe here the isolation and characterization of three floral organ number4 (fon4) alleles and the cloning of the FON4 gene. The fon4 mutants showed abnormal enlargement of the embryonic and vegetative shoot apical meristems (SAMs) and the inflorescence and floral meristems. Likely due to enlarged SAMs, fon4 mutants produced thick culms (stems) and increased numbers of both primary rachis branches and floral organs. We identified FON4 using a map-based cloning approach and found it encodes a small putatively secreted protein, which is the putative ortholog of the Arabidopsis (Arabidopsis thaliana) CLAVATA3 (CLV3) gene. FON4 transcripts mainly accumulated in the small group of cells at the apex of the SAMs, whereas the rice ortholog of CLV1 (FON1) is expressed throughout the SAMs, suggesting that the putative FON4 ligand might be sequestered as a possible mechanism for rice meristem regulation. Exogenous application of the peptides FON4p and CLV3p corresponding to the CLV3/ESR-related (CLE) motifs of FON4 and CLV3, respectively, resulted in termination of SAMs in rice, and treatment with CLV3p caused consumption of both rice and Arabidopsis root meristems, suggesting that the CLV pathway in limiting meristem size is conserved in both rice and Arabidopsis. However, exogenous FON4p did not have an obvious effect on limiting both rice and Arabidopsis root meristems, suggesting that the CLE motifs of Arabidopsis CLV3 and FON4 are potentially functionally divergent.
1 This work was supported by the National Key Basic Research Developments Program of the Ministry of Science and Technology, People's Republic of China (grant nos. 2006CB101700, 2005CB120802, and 2001CB109002), the National "863" High-Tech Project (grant no. 2005AA2710330), the Shanghai Municipal Committee of Science and Technology (grant no. 03JC14061), the Program for New Century Excellent Talents in University (grant no. NCET–04–0403), the Shuguang Scholarship (grant no. 04SG15), the Shanghai Institutes of Biological Sciences (Reproductive Development Project), and the U.S. Department of Energy (grant no. DE–FG02–02ER15332). 2 These authors contributed equally to the paper. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Dabing Zhang (zhangdb{at}sjtu.edu.cn). [W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.106.086736 * Corresponding author; e-mail zhangdb{at}sjtu.edu.cn; fax 86–21–34204869. Received July 14, 2006; accepted September 14, 2006; published September 29, 2006. This article has been cited by other articles:
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