Biology

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites areprohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Author's personal copy
Available online at www.sciencedirect.com

Integration oflocal and systemic signaling pathways for plant N responses
´ ´ Jose M Alvarez, Elena A Vidal and Rodrigo A Gutierrez
Nitrogen (N) is an essential macronutrient and a signal that has profound impacts on plant growth and development. In order to cope with changing N regimes in the soil, plants have developed complex regulatory mechanisms that involve shortrange and long-range signaling pathways.These pathways act at the cellular and whole plant scale to coordinate plant N metabolism, growth and development according to external and internal N status. Although molecular components of local and systemic N signaling have been identified and characterized, an integrated view of how plants coordinate and organize the N response is still lacking. In this review, we discuss recent advancestoward understanding the mechanisms of local and systemic N responses and provide an integrated model for how these responses are orchestrated.
Address FONDAP Center for Genome Regulation, Millennium Nucleus Center for ´ Plant Functional Genomics, Departamento de Genetica Molecular y ´ ´ Microbiologıa, Pontificia Universidad Catolica de Chile, Alameda 340, Santiago, Chile ´ Corresponding author:Gutierrez, Rodrigo A (rgutierrez@bio.puc.cl)

Current Opinion in Plant Biology 2012, 15:185–191 This review comes from a themed issue on Genome studies and molecular genetics Edited by Yves Van de Peer and J. Chris Pires Available online 3rd April 2012 1369-5266/$ – see front matter # 2012 Elsevier Ltd. All rights reserved. DOI 10.1016/j.pbi.2012.03.009

tissues and plant organs. An illustrativeexample of both local and systemic regulatory pathways at work can be found in the nitrate modulation of root system architecture (RSA). A local supply of nitrate promotes lateral root elongation in the nitrate-rich patch, while a high nitrate supply to whole roots has an inhibitory effect on lateral root development [3]. When two separate parts of the root are exposed to different nitrateconcentrations, systemic signals can communicate the N status of the plant and impact lateral root growth away from the site of nitrate perception. The long-distance systemic signaling is mediated by nitrate, but hormones such as cytokinins, can report the nitrate demand of the whole plant [4]. Nitrate uptake systems are also under control by both local signaling and systemic signaling driven by the Nstatus of the plant (reviewed in [5,6]). For instance, the expression of NRT2.1 that encodes a main component of the high-affinity transport system for root nitrate uptake [7] is induced by local nitrate supply [8] and repressed by systemic feedback signals exerted by high N status [9]. The interplay of local and systemic regulatory mechanisms for control of RSA allows plants to optimize nutrientacquisition in soils where N is heterogeneously distributed. In this review, we discuss recent advances and perspectives on deciphering local and systemic signaling pathways regulating plant N responses and how these processes may be integrated in cells and organs to generate a coherent organismal response.

Molecular mechanisms of the local N response
In land plants, the initial site of nutrient...