• Madiha Khan, Laura Ragni, Paul Tabb, Brenda C Salasini, Steven Chatfield, Raju Datla, John Lock, Xiahezi Kuai, Charles Després, Marcel Proveniers, Cao Yongguo, Daoquan Xiang, Halima Morin, Jean-Pierre Rullière, Sylvie Citerne, Shelley R Hepworth, and Véronique Pautot.
• Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6 (M.K., P.T., B.C.S., S.Ch., J.L., S.R.H.);Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique-AgroParisTech, Bâtiment 2, Institut National de la Recherche Agronomique Centre de Versailles-Grignon, 78026 Versailles cedex, France (L.R., H.M., J.-P.R., S.Ci., V.P.); Plant Biotechnology Institute,National Research Council Canada, Saskatoon, Saskatchewan, Canada S7N 0W9 (R.D., C.Y., D.X.);Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1 (X.K, C.D.); andMolecular Plant Physiology, Department of Biology, Faculty of Sciences, Utrecht University, CH-3584 Utrecht, The Netherlands (M.P.).
• Plant Physiol. 2015 Nov 1; 169 (3): 2166-86.

AbstractIn the model plant Arabidopsis (Arabidopsis thaliana), endogenous and environmental signals acting on the shoot apical meristem cause acquisition of inflorescence meristem fate. This results in changed patterns of aerial development seen as the transition from making leaves to the production of flowers separated by elongated internodes. Two related BEL1-like homeobox genes, PENNYWISE (PNY) and POUND-FOOLISH (PNF), fulfill this transition. Loss of function of these genes impairs stem cell maintenance and blocks internode elongation and flowering. We show here that pny pnf apices misexpress lateral organ boundary genes BLADE-ON-PETIOLE1/2 (BOP1/2) and KNOTTED-LIKE FROM ARABIDOPSIS THALIANA6 (KNAT6) together with ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1). Inactivation of genes in this module fully rescues pny pnf defects. We further show that BOP1 directly activates ATH1, whereas activation of KNAT6 is indirect. The pny pnf restoration correlates with renewed accumulation of transcripts conferring floral meristem identity, including FD, SQUAMOSA PROMOTER-BINDING PROTEIN LIKE genes, LEAFY, and APETALA1. To gain insight into how this module blocks flowering, we analyzed the transcriptome of BOP1-overexpressing plants. Our data suggest a central role for the microRNA156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE-microRNA172 module in integrating stress signals conferred in part by promotion of jasmonic acid biosynthesis. These data reveal a potential mechanism by which repression of lateral organ boundary genes by PNY-PNF is essential for flowering. © 2015 American Society of Plant Biologists. All Rights Reserved.

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