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First published online April 14, 2006; 10.1104/pp.106.077149 Plant Physiology 141:607-619 (2006) © 2006 American Society of Plant Biologists Mutations in the MicroRNA Complementarity Site of the INCURVATA4 Gene Perturb Meristem Function and Adaxialize Lateral Organs in Arabidopsis1,[W]División de Genética, Universidad Miguel Hernández, Campus de San Juan, 03550 Alicante, Spain (I.O., J.J.R., A.V., A.M.-L.); and División de Genética and Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain (S.J.-G., H.C., M.R.P., J.L.M.)
Here, we describe how the semidominant, gain-of-function icu4-1 and icu4-2 alleles of the INCURVATA4 (ICU4) gene alter leaf phyllotaxis and cell organization in the root apical meristem, reduce root length, and cause xylem overgrowth in the stem. The ICU4 gene was positionally cloned and found to encode the ATHB15 transcription factor, a class III homeodomain/leucine zipper family member, recently named CORONA. The icu4-1 and icu4-2 alleles bear the same point mutation that affects the microRNA complementarity site of ICU4 and is identical to those of several semidominant alleles of the class III homeodomain/leucine zipper family members PHABULOSA and PHAVOLUTA. The icu4-1 and icu4-2 mutations significantly increase leaf transcript levels of the ICU4 gene. The null hst-1 allele of the HASTY gene, which encodes a nucleocytoplasmic transporter, synergistically interacts with icu4-1, the double mutant displaying partial adaxialization of rosette leaves and carpels. Our results suggest that the ICU4 gene has an adaxializing function and that it is down-regulated by microRNAs that require the HASTY protein for their biogenesis.
1 This work was supported by the Ministerio de Educación y Ciencia of Spain (research grants BMC2002–02840 and BFU2005–01031 to J.L.M., BIO2002–04083–C03–03 to A.M.L., and BMC2003–09763 to M.R.P.). S.J.-G. and I.O. were fellows of the Ministerio de Educación y Ciencia of Spain and the Generalitat Valenciana, respectively. 2 These authors contributed equally to the paper. 3 Present address: Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720. 4 Present address: Plant Gene Expression Center, University of California, Albany, CA 94710. 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: José Luis Micol (jlmicol{at}umh.es). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.077149. * Corresponding author; e-mail jlmicol{at}umh.es; fax 34–96–665–8511. Received January 17, 2006; returned for revision March 16, 2006; accepted April 7, 2006. This article has been cited by other articles:
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