title: A Comparative Study of Ethylene Emanation upon Nitrogen Deficiency in Natural Accessions of Arabidopsis thaliana.
abstract: An original approach to develop sustainable agriculture with less nitrogen fertilizer inputs is to tackle the cross-talk between nitrogen nutrition and plant growth regulators. In particular the gaseous hormone, ethylene, is a prime target for that purpose. The variation of ethylene production in natural accessions of the model species Arabidopsis thaliana was explored in response to the nitrate supply. Ethylene was measured with a laser-based photoacoustic detector. First, experimental conditions were established with Columbia-0 (Col-0) accession, which was grown in vitro on horizontal plates across a range of five nitrate concentrations (0.5, 1, 2.5, 5, or 10 mM). The concentrations of 1 and 10 mM nitrate were retained for further characterization. Along with a decrease of total dry biomass and higher biomass allocation to the roots, the ethylene production was 50% more important at 1 mM than at 10 mM nitrate. The total transcript levels of 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASES (ACS) in roots and those of ACC OXIDASES (ACO) in shoots increased by 100% between the same treatments. This was mainly due to higher transcript levels of ACS6 and of ACO2 and ACO4 respectively. The assumption was that during nitrogen deficiency, the greater biomass allocation in favor of the roots was controlled by ethylene being released in the shoots after conversion of ACC originating from the roots. Second, biomass and ethylene productions were measured in 20 additional accessions. Across all accessions, the total dry biomass and ethylene production were correlated negatively at 1 mM but positively at 10 mM nitrate. Furthermore, polymorphism was surveyed in ACC and ethylene biosynthesis genes and gene products among accessions. Very few substitutions modifying the amino acids properties in conserved motifs of the enzymes were found in the accessions. Natural variation of ethylene production could be further explored to improve Nitrogen Use Efficiency (NUE), in particular by manipulating features like the biomass production and the timing of senescence upon nitrogen limitation.
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Interfacultary School of Bioengineers, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Hugues
authors.initials: H
authors.lastname: De Gernier
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Interfacultary School of Bioengineers, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Jérôme
authors.initials: J
authors.lastname: De Pessemier
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Interfacultary School of Bioengineers, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Xu
authors.affiliation: Trace Gas Research Group, Department of Molecular and Laser Physics, Institute for Molecules and Materials, Radboud University Nijmegen, Netherlands.
authors.forename: Simona M
authors.initials: SM
authors.lastname: Cristescu
authors.affiliation: Unit Hormone Signalling and Bio-Imaging, Laboratory of Functional Plant Biology, Department of Physiology, Ghent University Ghent, Belgium.
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Interfacultary School of Bioengineers, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Verbruggen
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Interfacultary School of Bioengineers, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Hermans
keywords: Arabidopsis; biomass; ethylene; natural variation; nitrogen