title: Cadmium-induced ethylene production and responses in Arabidopsis thaliana rely on ACS2 and ACS6 gene expression.
abstract: BACKGROUND
  Anthropogenic activities cause metal pollution worldwide. Plants can absorb and accumulate these metals through their root system, inducing stress as a result of excess metal concentrations inside the plant. Ethylene is a regulator of multiple plant processes, and is affected by many biotic and abiotic stresses. Increased ethylene levels have been observed after exposure to excess metals but it remains unclear how the increased ethylene levels are achieved at the molecular level. In this study, the effects of cadmium (Cd) exposure on the production of ethylene and its precursor 1-aminocyclopropane-1-carboxylic acid (ACC), and on the expression of the ACC Synthase (ACS) and ACC Oxidase (ACO) multigene families were investigated in Arabidopsis thaliana.
  
  
  RESULTS
  Increased ethylene release after Cd exposure was directly measurable in a system using rockwool-cultivated plants; enhanced levels of the ethylene precursor ACC together with higher mRNA levels of ethylene responsive genes: ACO2, ETR2 and ERF1 also indicated increased ethylene production in hydroponic culture. Regarding underlying mechanisms, it was found that the transcript levels of ACO2 and ACO4, the most abundantly expressed members of the ACO multigene family, were increased upon Cd exposure. ACC synthesis is the rate-limiting step in ethylene biosynthesis, and transcript levels of both ACS2 and ACS6 showed the highest increase and became the most abundant isoforms after Cd exposure, suggesting their importance in the Cd-induced increase of ethylene production.
  
  
  CONCLUSIONS
  Cadmium induced the biosynthesis of ACC and ethylene in Arabidopsis thaliana plants mainly via the increased expression of ACS2 and ACS6. This was confirmed in the acs2-1acs6-1 double knockout mutants, which showed a decreased ethylene production, positively affecting leaf biomass and resulting in a delayed induction of ethylene responsive gene expressions without significant differences in Cd contents between wild-type and mutant plants.
authors.forename: Kerim
authors.initials: K
authors.lastname: Schellingen
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
authors.forename: Filip
authors.initials: F
authors.lastname: Vandenbussche
authors.forename: Els
authors.initials: E
authors.lastname: Prinsen
authors.forename: Tony
authors.initials: T
authors.lastname: Remans
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, Diepenbeek, 3590, Belgium. ann.cuypers@uhasselt.be.
authors.forename: Ann
authors.initials: A
authors.lastname: Cuypers
mesh_terms: D000598:Amino Acids, Cyclic / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D002104:Cadmium / Q000494:pharmacology*; D005030:Ethylenes / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D000598:Amino Acids, Cyclic; D005030:Ethylenes; D002104:Cadmium; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase
references.citation: Plant Mol Biol. 2005 May;58(1):15-25
references.pmid: 16028113
references.citation: Plant Physiol Biochem. 2010 Aug;48(8):673-82
references.pmid: 20542443
references.citation: J Exp Bot. 2010 Sep;61(14):3885-99
references.pmid: 20627899
references.citation: J Plant Physiol. 2007 Nov;164(11):1480-8
references.pmid: 17215058
references.citation: Plant Physiol Biochem. 2008 Feb;46(2):212-8
references.pmid: 18024051
references.citation: J Biol Chem. 2003 Dec 5;278(49):49102-12
references.pmid: 12968022
references.citation: Plant Physiol. 2003 Oct;133(2):517-27
references.pmid: 12972669
references.citation: Plant Cell. 2003 Feb;15(2):545-59
references.pmid: 12566591
references.citation: J Exp Bot. 2009;60(12):3311-36
references.pmid: 19567479
references.citation: Physiol Plant. 2013 Mar;147(3):352-68
references.pmid: 22697433
references.citation: New Phytol. 2014 Jan;201(1):116-130
references.pmid: 24033367
references.citation: J Exp Bot. 2008;59(15):4119-31
references.pmid: 19036841
references.citation: Plant Mol Biol. 2003 Sep;53(1-2):117-31
references.pmid: 14756311
references.citation: Plant Physiol Biochem. 2012 Jul;56:79-96
references.pmid: 22609458
references.citation: Cancer Res. 2004 Aug 1;64(15):5245-50
references.pmid: 15289330
references.citation: Genome Biol. 2002 Jun 18;3(7):RESEARCH0034
references.pmid: 12184808
references.citation: Genetics. 2009 Nov;183(3):979-1003
references.pmid: 19752216
references.citation: Plant Signal Behav. 2009 Dec;4(12):1186-9
references.pmid: 20514243
references.citation: New Phytol. 2012 Jun;194(4):895-909
references.pmid: 22404712
references.citation: Plant Mol Biol. 1999 Jan;39(2):209-19
references.pmid: 10080689
references.citation: Plant Physiol. 2004 Oct;136(2):3276-83
references.pmid: 15448198
references.citation: Plant Cell. 2002;14 Suppl:S131-51
references.pmid: 12045274
references.citation: Planta. 2007 May;225(6):1353-65
references.pmid: 17143618
references.citation: Plant Physiol. 2004 Nov;136(3):3751-61
references.pmid: 15516515
references.citation: Planta. 2008 May;227(6):1343-9
references.pmid: 18273637
references.citation: Plant Biol (Stuttg). 2013 May;15(3):426-35
references.pmid: 23574304
references.citation: BMC Plant Biol. 2005 Aug 10;5:14
references.pmid: 16091151
references.citation: PLoS Genet. 2011 Apr;7(4):e1001370
references.pmid: 21533019
references.citation: Environ Sci Pollut Res Int. 2009 Nov;16(7):765-94
references.pmid: 19557448
references.citation: J Integr Plant Biol. 2008 Oct;50(10):1268-80
references.pmid: 19017114
references.citation: Plant Physiol. 2004 Oct;136(2):2982-3000
references.pmid: 15466221
references.citation: Int J Phytoremediation. 2011;13 Suppl 1:194-207
references.pmid: 22046760
references.citation: Plant Physiol. 2013 Jul;162(3):1566-82
references.pmid: 23719892
references.citation: Science. 2006 Jan 6;311(5757):91-4
references.pmid: 16400150
references.citation: Plant Physiol. 1988 Oct;88(2):506-10
references.pmid: 16666335
references.citation: Trends Plant Sci. 2013 Feb;18(2):92-9
references.pmid: 22981394
references.citation: Plant J. 2010 Oct;64(1):114-27
references.pmid: 20659280
references.citation: Development. 1999 Aug;126(16):3661-8
references.pmid: 10409511
references.citation: PLoS Genet. 2012 Jun;8(6):e1002767
references.pmid: 22761583
references.citation: Trends Plant Sci. 2009 May;14(5):270-9
references.pmid: 19375376
references.citation: Toxicol Appl Pharmacol. 2009 Aug 1;238(3):201-8
references.pmid: 19409405
references.citation: Funct Plant Biol. 2005 Jul;32(6):481-494
references.pmid: 32689149
references.citation: Genes Dev. 1998 Dec 1;12(23):3703-14
references.pmid: 9851977
references.citation: J Chromatogr A. 2003 Apr 18;993(1-2):79-87
references.pmid: 12735440
references.citation: Plant Cell. 1998 Aug;10(8):1321-32
references.pmid: 9707532
references.citation: Plant Physiol Biochem. 2011 Oct;49(10):1084-91
references.pmid: 21852144
references.citation: Environ Pollut. 2009 May;157(5):1581-8
references.pmid: 19211178
references.citation: Plant Physiol Biochem. 2011 Sep;49(9):1013-9
references.pmid: 21530288
references.citation: J Exp Bot. 2012 May;63(9):3415-28
references.pmid: 22403432
references.citation: J Exp Bot. 2002 Jan;53(366):1-11
references.pmid: 11741035
references.citation: Physiol Plant. 2009 May;136(1):94-109
references.pmid: 19508369
references.citation: Plant Physiol Biochem. 2009 Apr;47(4):308-12
references.pmid: 19153049
references.citation: Phytochemistry. 2010 Apr;71(5-6):614-8
references.pmid: 20116811
references.citation: Plant Physiol. 2009 May;150(1):229-43
references.pmid: 19279198
references.citation: Plant Physiol. 2007 Oct;145(2):465-77
references.pmid: 17720753
references.citation: Proc Natl Acad Sci U S A. 1998 Aug 18;95(17):10334-9
references.pmid: 9707648
references.citation: Plant Cell Environ. 2002 Jun;25(6):793-801
references.pmid: 12092614
references.citation: J Exp Bot. 2008;59(11):3039-50
references.pmid: 18573798
references.citation: Biometals. 2010 Oct;23(5):927-40
references.pmid: 20361350
references.citation: Trends Plant Sci. 2002 Jul;7(7):309-15
references.pmid: 12119168
references.citation: Plant Cell Physiol. 1998 Jun;39(6):565-73
references.pmid: 9697341