title: Hardening with salicylic acid induces concentration-dependent changes in abscisic acid biosynthesis of tomato under salt stress.
abstract: The role of salicylic acid (SA) in the control of abscisic acid (ABA) biosynthesis is controversial although both plant growth regulators may accumulate in tissues under abiotic and biotic stress conditions. Hardening of tomato plants to salinity stress with 10(-4)M SA ("high SA") resulted in an up-regulation of ABA biosynthesis genes, zeaxanthin epoxidase (SlZEP1), 9-cis-epoxycarotenoid dioxygenase (SlNCED1) and aldehyde oxidases (SlAO1 and SlAO2) in the roots and led to ABA accumulation both in root and leaf tissues. In plants pre-treated with lower concentration of SA (10(-7)M, "low SA"), the up-regulation of SlNCED1 in the roots promoted ABA accumulation in the root tissues but the hormone concentration remained at control level in the leaves. Salt stress induced by 100mM NaCl reduced the transcript abundance of ABA biosynthetic genes and inhibited SlAO activity in plants hardened with "high SA", but the tissues maintained root ABA level over the untreated control. The combined effect of "high SA" and ABA under salt stress led to partially recovered photosynthetic activity, reduced ethylene production in root apices, and restored root growth, which is one of the main features of salt tolerance. Unlike "high SA", hardening with "low SA" had no influence on ethylene production, and led to reduced elongation of roots in plants exposed to 100mM NaCl. The up-regulation of carotenoid cleavage dioxygenases SlCCD1A and SlCCD1B by SA, which produce apocarotenoids, may open new pathways in SA sensing and signalling processes.
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary. Electronic address: horvathedo@yahoo.com.
authors.forename: Edit
authors.initials: E
authors.lastname: Horváth
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
authors.forename: Jolán
authors.initials: J
authors.lastname: Csiszár
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Gallé
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Poór
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Szepesi
authors.affiliation: Department of Plant Biology, Faculty of Sciences, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary. Electronic address: tari@bio.u-szeged.hu.
authors.forename: Irma
authors.initials: I
authors.lastname: Tari
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology*; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D010940:Plant Proteins; D012965:Sodium Chloride; D000040:Abscisic Acid; D020156:Salicylic Acid
keywords: Abscisic acid biosynthesis; Carotenoid cleavage dioxygenases; Ethylene production; Salicylic acid; Salt stress; Tomato