title: Non-targeted profiling of semi-polar metabolites in Arabidopsis root exudates uncovers a role for coumarin secretion and lignification during the local response to phosphate limitation.
abstract: Plants have evolved two major strategies to cope with phosphate (Pi) limitation. The systemic response, mainly comprising increased Pi uptake and metabolic adjustments for more efficient Pi use, and the local response, enabling plants to explore Pi-rich soil patches by reorganization of the root system architecture. Unlike previous reports, this study focused on root exudation controlled by the local response to Pi deficiency. To approach this, a hydroponic system separating the local and systemic responses was developed. Arabidopsis thaliana genotypes exhibiting distinct sensitivities to Pi deficiency could be clearly distinguished by their root exudate composition as determined by non-targeted reversed-phase ultraperformance liquid chromatography electrospray ionization quadrupole-time-of-flight mass spectrometry metabolite profiling. Compared with wild-type plants or insensitive low phosphate root 1 and 2 (lpr1 lpr2) double mutant plants, the hypersensitive phosphate deficiency response 2 (pdr2) mutant exhibited a reduced number of differential features in root exudates after Pi starvation, suggesting the involvement of PDR2-encoded P5-type ATPase in root exudation. Identification and analysis of coumarins revealed common and antagonistic regulatory pathways between Pi and Fe deficiency-induced coumarin secretion. The accumulation of oligolignols in root exudates after Pi deficiency was inversely correlated with Pi starvation-induced lignification at the root tips. The strongest oligolignol accumulation in root exudates was observed for the insensitive lpr1 lpr2 double mutant, which was accompanied by the absence of Pi deficiency-induced lignin deposition, suggesting a role of LPR ferroxidases in lignin polymerization during Pi starvation.
authors.affiliation: Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany joerg.ziegler@ipb-halle.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Ziegler
authors.affiliation: Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmidt
authors.affiliation: Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Ranju
authors.initials: R
authors.lastname: Chutia
authors.affiliation: Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
authors.affiliation: Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Böttcher
authors.affiliation: Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Strehmel
authors.affiliation: Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
authors.forename: Dierk
authors.initials: D
authors.lastname: Scheel
authors.affiliation: Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany Department of Plant Sciences, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Steffen
authors.initials: S
authors.lastname: Abel
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism; D016000:Cluster Analysis; D003374:Coumarins / Q000378:metabolism*; D018527:Hydroponics; D008031:Lignin / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D018519:Meristem / Q000187:drug effects / Q000378:metabolism; D055442:Metabolome / Q000187:drug effects*; D055432:Metabolomics / Q000379:methods*; D010696:Phloroglucinol / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology*; D053147:Plant Exudates / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003374:Coumarins; D008293:Malates; D010710:Phosphates; D053147:Plant Exudates; D019343:Citric Acid; C030298:malic acid; D008031:Lignin; D001120:Arginine; C030123:coumarin; D010696:Phloroglucinol
keywords: Arabidopsis thaliana; coumarin; hydroponic system; lignification; metabolite profiling; oligolignol; phosphate starvation; root exudates.