title: Fine-tuning of root elongation by ethylene: a tool to study dynamic structure-function relationships between root architecture and nitrate absorption.
abstract: Background Recently developed genetic and pharmacological approaches have been used to explore NO3-/ethylene signalling interactions and how the modifications in root architecture by pharmacological modulation of ethylene biosynthesis affect nitrate uptake. Key Results Structure-function studies combined with recent approaches to chemical genomics highlight the non-specificity of commonly used inhibitors of ethylene biosynthesis such as AVG (l-aminoethoxyvinylglycine). Indeed, AVG inhibits aminotransferases such as ACC synthase (ACS) and tryptophan aminotransferase (TAA) involved in ethylene and auxin biosynthesis but also some aminotransferases implied in nitrogen (N) metabolism. In this framework, it can be assumed that the products of nitrate assimilation and hormones may interact through a hub in carbon (C) and N metabolism to drive the root morphogenetic programme (RMP). Although ethylene/auxin interactions play a major role in cell division and elongation in root meristems, shaping of the root system depends also on energetic considerations. Based on this finding, the analysis is extended to nutrient ion-hormone interactions assuming a fractal or constructal model for root development. Conclusion Therefore, the tight control of root structure-function in the RMP may explain why over-expressing nitrate transporter genes to decouple structure-function relationships and improve nitrogen use efficiency (NUE) has been unsuccessful.
authors.affiliation: Université de Caen Basse-Normandie, UMR Écophysiologie Végétale & Agronomie, Nutritions NCS, F-14032 Caen, France.|INRA, UMR 950, Écophysiologie Végétale & Agronomie, Nutritions NCS, F-14032 Caen, France.
authors.forename: Erwan
authors.initials: E
authors.lastname: Le Deunff
authors.affiliation: East Malling Research, New Road, East Malling ME19 6BJ, Kent, UK.
authors.forename: Julien
authors.initials: J
authors.lastname: Lecourt
authors.affiliation: Université Blaise Pascal-INRA, 24, avenue des Landais, BP 80 006, F-63177 Aubière, France.|INRA, UMR 547 PIAF, Bâtiment Biologie Végétale Recherche, BP 80 006, F-63177 Aubière, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Malagoli
keywords: 1-aminocyclopropane-1-carboxylic acid; Nitrate uptake; aminotransferases; auxin biosynthesis; ethylene biosynthesis; l-aminoethoxyvinyl-glycine; nitrogen use efficiency; root architecture