title: Cytokinin regulation of auxin synthesis in Arabidopsis involves a homeostatic feedback loop regulated via auxin and cytokinin signal transduction.
abstract: Together, auxin and cytokinin regulate many of the processes that are critical to plant growth, development, and environmental responsiveness. We have previously shown that exogenous auxin regulates cytokinin biosynthesis in Arabidopsis thaliana. In this work, we show that, conversely, the application or induced ectopic biosynthesis of cytokinin leads to a rapid increase in auxin biosynthesis in young, developing root and shoot tissues. We also show that reducing endogenous cytokinin levels, either through the induction of CYTOKININ OXIDASE expression or the mutation of one or more of the cytokinin biosynthetic ISOPENTENYLTRANSFERASE genes leads to a reduction in auxin biosynthesis. Cytokinin modifies the abundance of transcripts for several putative auxin biosynthetic genes, suggesting a direct induction of auxin biosynthesis by cytokinin. Our data indicate that cytokinin is essential, not only to maintain basal levels of auxin biosynthesis in developing root and shoot tissues but also for the dynamic regulation of auxin biosynthesis in response to changing developmental or environmental conditions. In combination with our previous work, the data suggest that a homeostatic feedback regulatory loop involving both auxin and cytokinin signaling acts to maintain appropriate auxin and cytokinin concentrations in developing root and shoot tissues.
authors.affiliation: Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Brian
authors.initials: B
authors.lastname: Jones
authors.forename: Sara Andersson
authors.initials: SA
authors.lastname: Gunnerås
authors.forename: Sara V
authors.initials: SV
authors.lastname: Petersson
authors.forename: Petr
authors.initials: P
authors.lastname: Tarkowski
authors.forename: Neil
authors.initials: N
authors.lastname: Graham
authors.forename: Sean
authors.initials: S
authors.lastname: May
authors.forename: Karel
authors.initials: K
authors.lastname: Dolezal
authors.forename: Göran
authors.initials: G
authors.lastname: Sandberg
authors.forename: Karin
authors.initials: K
authors.lastname: Ljung
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D007210:Indoleacetic Acids / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids
references.citation: Plant Cell. 2007 Jul;19(7):2169-85
references.pmid: 17630276
references.citation: Nat Methods. 2005 Aug;2(8):615-9
references.pmid: 16170893
references.citation: Annu Rev Genet. 2009;43:265-85
references.pmid: 19686081
references.citation: Plant Biol (Stuttg). 2006 May;8(3):389-96
references.pmid: 16807832
references.citation: Nature. 2008 Jun 19;453(7198):1094-7
references.pmid: 18463635
references.citation: Plant Cell. 2002 Feb;14(2):421-33
references.pmid: 11884684
references.citation: Proc Natl Acad Sci U S A. 2004 May 25;101(21):8039-44
references.pmid: 15146070
references.citation: Plant Cell. 1990 Nov;2(11):1071-80
references.pmid: 1983791
references.citation: Curr Opin Plant Biol. 2007 Dec;10(6):639-44
references.pmid: 17692560
references.citation: Nature. 2005 May 26;435(7041):446-51
references.pmid: 15917798
references.citation: Cold Spring Harb Perspect Biol. 2010 Jan;2(1):a001594
references.pmid: 20182605
references.citation: Science. 2008 Nov 28;322(5906):1380-4
references.pmid: 19039136
references.citation: Plant Mol Biol. 2002 Jun-Jul;49(3-4):411-26
references.pmid: 12036264
references.citation: Plant Mol Biol. 2009 Mar;69(4):429-35
references.pmid: 18974937
references.citation: Genome Biol. 2002 Jun 18;3(7):RESEARCH0034
references.pmid: 12184808
references.citation: J Biol Chem. 2004 Oct 1;279(40):41866-72
references.pmid: 15280363
references.citation: Science. 1998 Feb 27;279(5355):1371-3
references.pmid: 9478901
references.citation: Plant J. 2001 Nov;28(4):465-74
references.pmid: 11737783
references.citation: Plant J. 2004 Jan;37(1):128-38
references.pmid: 14675438
references.citation: Plant Cell. 2008 Jan;20(1):88-100
references.pmid: 18223038
references.citation: Trends Plant Sci. 2008 Feb;13(2):85-92
references.pmid: 18262459
references.citation: Plant Cell. 2006 Nov;18(11):3073-87
references.pmid: 17122069
references.citation: Proc Natl Acad Sci U S A. 2000 Dec 19;97(26):14778-83
references.pmid: 11114204
references.citation: Nat Chem Biol. 2009 May;5(5):325-32
references.pmid: 19377459
references.citation: Nature. 2006 Sep 28;443(7110):458-61
references.pmid: 17006513
references.citation: Plant Mol Biol. 2006 Apr;60(6):871-87
references.pmid: 16724258
references.citation: Plant Physiol. 2005 Jan;137(1):253-62
references.pmid: 15579661
references.citation: Plant J. 2006 Mar;45(6):1028-36
references.pmid: 16507092
references.citation: Proc Natl Acad Sci U S A. 2009 Mar 17;106(11):4284-9
references.pmid: 19246387
references.citation: Plant Cell. 2009 Jun;21(6):1659-68
references.pmid: 19491238
references.citation: Annu Rev Plant Biol. 2006;57:431-49
references.pmid: 16669769
references.citation: Trends Plant Sci. 2003 Apr;8(4):165-71
references.pmid: 12711228
references.citation: J Exp Bot. 2008;59(1):67-74
references.pmid: 17728300
references.citation: Trends Plant Sci. 2009 Oct;14(10):557-62
references.pmid: 19734082
references.citation: Plant Cell. 2007 Jul;19(7):2197-212
references.pmid: 17630274
references.citation: Cell. 2008 Apr 4;133(1):177-91
references.pmid: 18394997
references.citation: Plant J. 2007 Oct;52(1):114-23
references.pmid: 17655650
references.citation: Plant Cell. 2007 Jul;19(7):2186-96
references.pmid: 17630275
references.citation: Plant J. 1996 Sep;10(3):403-13
references.pmid: 8811856
references.citation: Plant J. 2005 Nov;44(3):382-95
references.pmid: 16236149
references.citation: Plant Cell. 2005 Apr;17(4):1090-104
references.pmid: 15772288
references.citation: Plant Cell. 2004 Mar;16(3):658-71
references.pmid: 14973166
references.citation: Nature. 2005 May 26;435(7041):441-5
references.pmid: 15917797
references.citation: Plant Physiol. 2003 Jan;131(1):167-76
references.pmid: 12529525
references.citation: Ann Bot. 2005 Apr;95(5):707-35
references.pmid: 15749753
references.citation: Plant Cell. 2003 Nov;15(11):2532-50
references.pmid: 14555694
references.citation: Annu Rev Plant Biol. 2007;58:93-113
references.pmid: 17177637
references.citation: Trends Plant Sci. 1997 Sep;2(9):351-6
references.pmid: 11540614