Ignacio Rubio Somoza

Publications (20) View all

• Article: Coordination of Flower Maturation by a Regulatory Circuit of Three MicroRNAs.

  Ignacio Rubio-Somoza, Detlef Weigel
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  ABSTRACT: The development of multicellular organisms relies on interconnected genetic programs that control progression through their life cycle. MicroRNAs (miRNAs) and transcription factors (TFs) play key roles in such regulatory circuits. Here, we describe how three evolutionary conserved miRNA-TF pairs interact to form multiple checkpoints during reproductive development of Arabidopsis thaliana. Genetic, cellular, and physiological experiments show that miR159- and miR319-regulated MYB and TCP transcription factors pattern the expression of miR167 family members and their ARF6/8 targets. Coordinated action of these miRNA-TF pairs is crucial for the execution of consecutive hormone-dependent transitions during flower maturation. Cross-regulation includes both cis- and trans-regulatory interactions between these miRNAs and their targets. Our observations reveal how different miRNA-TF pairs can be organized into modules that coordinate successive steps in the plant life cycle.
  PLoS Genetics 03/2013; 9(3):e1003374. · 8.69 Impact Factor
• Article: A Protodermal miR394 Signal Defines a Region of Stem Cell Competence in the Arabidopsis Shoot Meristem.

  Steffen Knauer, Anna L Holt, Ignacio Rubio-Somoza, Elise J Tucker, Annika Hinze, Melanie Pisch, Marie Javelle, Marja C Timmermans, Matthew R Tucker, Thomas Laux
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  ABSTRACT: A long-standing question in plants and animals is how spatial patterns are maintained within stem cell niches despite ongoing cell divisions. Here we address how, during shoot meristem formation in Arabidopsis thaliana, the three apical cell layers acquire stem cell identity. Using a sensitized mutant screen, we identified miR394 as a mobile signal produced by the surface cell layer (the protoderm) that confers stem cell competence to the distal meristem by repressing the F box protein LEAF CURLING RESPONSIVENESS. This repression is required to potentiate signaling from underneath the stem cells by the transcription factor WUSCHEL, maintaining stem cell pluripotency. The interaction of two opposing signaling centers provides a mechanistic framework of how stem cells are localized at the tip of the meristem. Although the constituent cells change, the surface layer provides a stable point of reference in the self-organizing meristem.
  Developmental cell 01/2013; · 13.36 Impact Factor
• Article: Modulation of Plant Defenses by Ethylene

  Bruce Adie, José Manuel Chico, Ignacio Rubio-Somoza, Roberto Solano
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  ABSTRACT: Ethylene (ET) plays a critical role in the activation of plant defenses against different biotic stresses through its participation in a complex signaling network that includes jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA). Pathogen attack, wounding, and herbivory trigger asymmetric activation of this defense signaling network, thereby affecting the final balance of interactions between its components and establishing a targeted response to the initial threat. Ethylene’s contribution to the modulation of this defense network relies on the complexity of the regulation of multigene families involved in ET biosynthesis, signal transduction, and crosstalk and enables the plant to fine-tune its response. The function of the members of these multigene families is tightly regulated at transcriptional, post-transcriptional, and post-translational levels. It is generally accepted that ET cooperates with JA in the activation of defenses against necrotrophic pathogens and antagonizes SA-dependent resistance against biotrophic pathogens. However, this is likely an oversimplified view, because cooperative interactions between ET and SA pathways have been reported and ET has been implicated in the activation of defenses against some biotrophic and hemibiotrophic pathogens. Therefore, deciphering ET’s place in this hormonal network is essential to understanding how the cell orchestrates an optimal response to a specific biotic stress.
  Journal of Plant Growth Regulation 04/2012; 26(2):160-177. · 2.86 Impact Factor
• Article: Interplay of SLIM1 and miR395 in the regulation of sulfate assimilation in Arabidopsis

  Cintia G. Kawashima, Colette A. Matthewman, Siqi Huang, Bok-Rye Lee, Naoko Yoshimoto, Anna Koprivova, Ignacio Rubio-Somoza, Marco Todesco, Tina Rathjen, Kazuki Saito, Hideki Takahashi, Tamas Dalmay, Stanislav Kopriva
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  ABSTRACT: MicroRNAs play a key role in the control of plant development and response to adverse environmental conditions. For example, microRNA395 (miR395), which targets three out of four isoforms of ATP sulfurylase, the first enzyme of sulfate assimilation, as well as a low-affinity sulfate transporter, SULTR2;1, is strongly induced by sulfate deficiency. However, other components of sulfate assimilation are induced by sulfate starvation, so that the role of miR395 is counterintuitive. Here, we describe the regulation of miR395 and its targets by sulfate starvation. We show that miR395 is important for the increased translocation of sulfate to the shoots during sulfate starvation. MiR395 together with the SULFUR LIMITATION 1 transcription factor maintain optimal levels of ATP sulfurylase transcripts to enable increased flux through the sulfate assimilation pathway in sulfate-deficient plants. Reduced expression of ATP sulfurylase (ATPS) alone affects both sulfate translocation and flux, but SULTR2;1 is important for the full rate of sulfate translocation to the shoots. Thus, miR395 is an integral part of the regulatory circuit controlling plant sulfate assimilation with a complex mechanism of action.
  The Plant Journal 04/2011; 66(5):863 - 876. · 6.16 Impact Factor
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  Available from: Ignacio Rubio Somoza

  Article: Regulation and functional specialization of small RNA-target nodes during plant development.

  Ignacio Rubio-Somoza, Joshua T Cuperus, Detlef Weigel, James C Carrington
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  ABSTRACT: The expansion of gene families for miRNA and tasiRNA, small RNA effector proteins (ARGONAUTEs or AGOs), and miRNA/tasiRNA targets has contributed to regulatory diversity in plants. Loss or acquisition of small RNA-generating loci and target site sequences in multigene families represent striking examples of subfunctionalization or neo-functionalization, where regulatory diversity is achieved at the post-transcriptional level. Differential regulation of small RNA and target gene family members, and evolution of unique functionality of distinct small RNA-AGO complexes, provide further regulatory diversity. Here, we focus on the idea of distinct small RNA-target transcript pairs as nodes within biological networks, and review progress toward understanding the role of small RNA-target nodes in the context of auxin signaling.
  Current opinion in plant biology 09/2009; 12(5):622-7. · 10.33 Impact Factor