title: Apocarotenoids: hormones, mycorrhizal metabolites and aroma volatiles.
abstract: Apocarotenoids are tailored from carotenoids by oxidative enzymes [carotenoid cleavage oxygenases (CCOs)], cleaving specific double bonds of the polyene chain. The cleavage products can act as hormones, signaling compounds, chromophores and scent/aroma constituents. Recent advances were the identification of strigolactones as apocarotenoids and the description of their novel role as shoot branching inhibitor hormones. Strigolactones are also involved in plant signaling to both harmful (parasitic weeds) and beneficial [arbuscular mycorrhizal (AM) fungi] rhizosphere residents. This review describes the progress in the characterization of CCOs, termed CCDs and NCEDs, in plants. It highlights the importance of sequential cleavage reactions of C(40) carotenoid precursors, the apocarotenoid cleavage oxygenase (ACO) nature of several CCOs and the topic of compartmentation. Work on the biosynthesis of abundant C(13) cyclohexenone and C(14) mycorradicin apocarotenoids in mycorrhizal roots has revealed a new role of CCD1 as an ACO of C(27) apocarotenoid intermediates, following their predicted export from plastid to cytosol. Manipulation of the AM-induced apocarotenoid pathway further suggests novel roles of C(13) apocarotenoids in controlling arbuscule turnover in the AM symbiosis. CCD7 has been established as a biosynthetic crosspoint, controlling both strigolactone and AM-induced C(13) apocarotenoid biosynthesis. Interdependence of the two apocarotenoid pathways may thus play a role in AM-mediated reduction of parasitic weed infestations. Potential scenarios of C(13) scent/aroma volatile biogenesis are discussed, including the novel mechanism revealed from mycorrhizal roots. The recent progress in apocarotenoid research opens up new perspectives for fundamental work, but has also great application potential for the horticulture, food and fragrance industries.
authors.affiliation: Abteilung Sekundärstoffwechsel, Leibniz-Institut für Pflanzenbiochemie, Halle (Saale), Germany. mhwalter@ipb-halle.de
authors.forename: Michael H
authors.initials: MH
authors.lastname: Walter
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Floss
authors.forename: Dieter
authors.initials: D
authors.lastname: Strack
mesh_terms: D002338:Carotenoids / Q000502:physiology*; D038821:Mycorrhizae / Q000502:physiology*; D009812:Odorants; D014835:Volatilization
chemical_list: D002338:Carotenoids
references.citation: Nature. 2009 Dec 3;462(7273):575-6
references.pmid: 19956245
references.citation: Cell Mol Life Sci. 2006 Oct;63(19-20):2291-303
references.pmid: 16909205
references.citation: FEBS J. 2009 Oct;276(19):5416-31
references.pmid: 19703230
references.citation: Plant J. 2006 Mar;45(6):982-93
references.pmid: 16507088
references.citation: Plant Physiol. 2003 Apr;131(4):1591-601
references.pmid: 12692318
references.citation: Curr Opin Plant Biol. 2003 Aug;6(4):358-64
references.pmid: 12873531
references.citation: Phytochemistry. 2009 Oct-Nov;70(15-16):1867-75
references.pmid: 19665150
references.citation: Curr Opin Chem Biol. 2002 Apr;6(2):193-201
references.pmid: 12039004
references.citation: J Biol Chem. 2008 Sep 5;283(36):24816-25
references.pmid: 18611853
references.citation: Phytochemistry. 2006 Apr;67(7):636-40
references.pmid: 16483620
references.citation: Proc Natl Acad Sci U S A. 1997 Oct 28;94(22):12235-40
references.pmid: 9342392
references.citation: Plant Cell Physiol. 2009 Aug;50(8):1416-24
references.pmid: 19542179
references.citation: Biosci Biotechnol Biochem. 2007 Jun;71(6):1405-14
references.pmid: 17587670
references.citation: Trends Plant Sci. 2009 Jul;14(7):364-72
references.pmid: 19540149
references.citation: Plant J. 2010 Jan;61(2):300-11
references.pmid: 19845881
references.citation: Plant J. 2002 Aug;31(3):243-54
references.pmid: 12164805
references.citation: Plant Cell Physiol. 2002 Mar;43(3):256-65
references.pmid: 11917079
references.citation: Nature. 2008 Sep 11;455(7210):195-200
references.pmid: 18690207
references.citation: Curr Opin Plant Biol. 2006 Jun;9(3):315-21
references.pmid: 16616608
references.citation: Plant J. 2003 Jul;35(1):44-56
references.pmid: 12834401
references.citation: New Phytol. 2006;172(1):22-34
references.pmid: 16945086
references.citation: Can J Microbiol. 1976 Jan;22(1):64-75
references.pmid: 1252991
references.citation: Plant Physiol. 2008 Nov;148(3):1267-82
references.pmid: 18790999
references.citation: Nature. 2005 Jun 9;435(7043):824-7
references.pmid: 15944706
references.citation: Mol Microbiol. 2005 Feb;55(4):1015-24
references.pmid: 15686550
references.citation: Plant J. 2007 Feb;49(4):619-28
references.pmid: 17217459
references.citation: Plant Cell. 2003 Jan;15(1):47-62
references.pmid: 12509521
references.citation: Plant Physiol. 2009 Nov;151(3):985-90
references.pmid: 19767387
references.citation: Phytochemistry. 2009 Mar;70(4):457-64
references.pmid: 19264332
references.citation: Curr Opin Plant Biol. 2010 Feb;13(1):34-9
references.pmid: 19913454
references.citation: Curr Opin Plant Biol. 2007 Oct;10(5):473-6
references.pmid: 17884716
references.citation: Plant J. 2007 Sep;51(6):1019-29
references.pmid: 17655651
references.citation: Proc Natl Acad Sci U S A. 2001 Jan 30;98(3):1130-5
references.pmid: 11158606
references.citation: J Agric Food Chem. 2003 Apr 9;51(8):2384-9
references.pmid: 12670185
references.citation: Plant Signal Behav. 2007 Jan;2(1):58-62
references.pmid: 19516969
references.citation: New Phytol. 2008;178(4):863-874
references.pmid: 18346111
references.citation: Genes Dev. 2003 Jun 15;17(12):1469-74
references.pmid: 12815068
references.citation: Mycorrhiza. 2009 Jun;19(5):287-294
references.pmid: 19238457
references.citation: Plant J. 2004 Dec;40(6):882-92
references.pmid: 15584954
references.citation: Biochem J. 2008 Dec 1;416(2):289-96
references.pmid: 18637791
references.citation: Phytochemistry. 2004 Nov;65(22):3057-63
references.pmid: 15504441
references.citation: J Biol Chem. 2001 Apr 27;276(17):14110-6
references.pmid: 11278918
references.citation: Proc Natl Acad Sci U S A. 2007 Jan 30;104(5):1720-5
references.pmid: 17242358
references.citation: J Biol Chem. 2001 Mar 2;276(9):6560-5
references.pmid: 11092891
references.citation: Trends Plant Sci. 2003 Apr;8(4):145-9
references.pmid: 12711223
references.citation: Trends Plant Sci. 2007 May;12(5):224-30
references.pmid: 17416544
references.citation: J Nutr. 2004 Jan;134(1):251S-6S
references.pmid: 14704329
references.citation: Planta. 2009 Dec;231(1):1-12
references.pmid: 19888599
references.citation: Fungal Genet Biol. 2007 Nov;44(11):1096-108
references.pmid: 17822929
references.citation: J Biol Chem. 2004 Nov 5;279(45):46940-5
references.pmid: 15342640
references.citation: Plant Cell Physiol. 2006 Aug;47(8):1124-34
references.pmid: 16854943
references.citation: Plant Signal Behav. 2009 Mar;4(3):172-5
references.pmid: 19721743
references.citation: J Exp Bot. 2005 Oct;56(420):2721-31
references.pmid: 16131507
references.citation: Planta. 2008 Oct;228(5):789-801
references.pmid: 18716794
references.citation: Planta. 2009 Sep;230(4):649-58
references.pmid: 19579033
references.citation: Plant Physiol. 1995 Oct;109(2):465-70
references.pmid: 7480342
references.citation: Arch Biochem Biophys. 2009 Mar 15;483(2):236-45
references.pmid: 19320050
references.citation: Phytochemistry. 2007 Jan;68(1):130-8
references.pmid: 17084869
references.citation: Fungal Genet Biol. 2009 Oct;46(10):803-13
references.pmid: 19584000
references.citation: J Agric Food Chem. 2009 Feb 25;57(4):1513-20
references.pmid: 19166317
references.citation: Plant Physiol. 2006 Mar;140(3):984-97
references.pmid: 16461379
references.citation: J Biol Chem. 2000 Apr 21;275(16):11915-20
references.pmid: 10766819
references.citation: J Exp Bot. 2010;61(1):105-19
references.pmid: 19767307
references.citation: Plant Mol Biol. 2008 Nov;68(4-5):423-37
references.pmid: 18716882
references.citation: Curr Biol. 2004 Jul 27;14(14):1232-8
references.pmid: 15268852
references.citation: Biosci Biotechnol Biochem. 2004 Jun;68(6):1366-8
references.pmid: 15215605
references.citation: J Biol Chem. 2007 Nov 16;282(46):33553-33561
references.pmid: 17855355
references.citation: Plant Physiol. 2009 Dec;151(4):1867-77
references.pmid: 19846541
references.citation: Plant J. 2007 Jun;50(5):810-24
references.pmid: 17470058
references.citation: Mol Microbiol. 2008 Jul;69(1):231-44
references.pmid: 18485074
references.citation: Chembiochem. 2008 Jun 16;9(9):1450-61
references.pmid: 18478524
references.citation: Science. 1997 Jun 20;276(5320):1872-4
references.pmid: 9188535
references.citation: Trends Plant Sci. 2005 Apr;10(4):187-94
references.pmid: 15817420
references.citation: Plant J. 2007 Apr;50(1):80-94
references.pmid: 17346265
references.citation: J Biol Chem. 2008 Apr 25;283(17):11364-73
references.pmid: 18285342
references.citation: Plant J. 2008 Oct;56(1):86-100
references.pmid: 18557838
references.citation: FEBS J. 2009 Feb;276(3):736-47
references.pmid: 19120446
references.citation: J Biol Chem. 2006 Oct 20;281(42):31583-93
references.pmid: 16920703
references.citation: J Agric Food Chem. 2008 Oct 8;56(19):9277-85
references.pmid: 18778069
references.citation: Mycorrhiza. 2009 Sep;19(7):449-459
references.pmid: 19629541
references.citation: Appl Microbiol Biotechnol. 2005 May;67(3):322-35
references.pmid: 15635463
references.citation: Curr Biol. 2004 Oct 5;14(19):1739-46
references.pmid: 15458645
references.citation: Plant Cell. 2009 May;21(5):1512-25
references.pmid: 19470589
references.citation: Nature. 2008 Sep 11;455(7210):189-94
references.pmid: 18690209
references.citation: Phytochemistry. 2009 May;70(8):1009-16
references.pmid: 19473679
references.citation: J Exp Bot. 2009;60(11):3011-22
references.pmid: 19436048
references.citation: Plant Physiol. 2007 Feb;143(2):697-706
references.pmid: 17158589
references.citation: J Biol Chem. 2005 Aug 12;280(32):29217-23
references.pmid: 15951442
references.citation: Phytochemistry. 2006 Aug;67(15):1579-89
references.pmid: 16563447
references.citation: Plant Mol Biol. 2009 Oct;71(3):265-76
references.pmid: 19603144
references.citation: Curr Opin Plant Biol. 2009 Oct;12(5):556-61
references.pmid: 19726222
references.citation: Plant Cell. 2005 Mar;17(3):746-59
references.pmid: 15705953
references.citation: Plant J. 2000 Mar;21(6):571-8
references.pmid: 10758508
references.citation: Plant Physiol. 2005 Oct;139(2):920-34
references.pmid: 16183851
references.citation: Plant Physiol. 2004 Nov;136(3):3504-14
references.pmid: 15516502
references.citation: Science. 2005 Apr 8;308(5719):267-9
references.pmid: 15821095
references.citation: J Biol Chem. 2001 Jul 6;276(27):25208-11
references.pmid: 11316814
references.citation: Plant Physiol. 2004 Feb;134(2):614-24
references.pmid: 14764905
references.citation: Annu Rev Plant Biol. 2005;56:165-85
references.pmid: 15862093
references.citation: Plant Cell Physiol. 2005 Jan;46(1):79-86
references.pmid: 15659436
references.citation: Eukaryot Cell. 2007 Apr;6(4):650-7
references.pmid: 17293483
references.citation: Plant Physiol. 2009 Sep;151(1):400-12
references.pmid: 19641034
references.citation: Plant Physiol. 2006 Nov;142(3):1193-201
references.pmid: 16980560
references.citation: Plant Cell. 2005 Feb;17(2):464-74
references.pmid: 15659639
references.citation: Dev Cell. 2005 Mar;8(3):443-9
references.pmid: 15737939
references.citation: J Exp Bot. 2006;57(10):2153-64
references.pmid: 16714310
references.citation: Dev Cell. 2008 Sep;15(3):337-338
references.pmid: 18804430
references.citation: Plant J. 2008 Aug;55(4):709-17
references.pmid: 18466302
references.citation: Science. 2003 Jun 27;300(5628):2089-91
references.pmid: 12829782
references.citation: Plant Physiol. 2006 Nov;142(3):1014-26
references.pmid: 16980559
references.citation: J Biol Chem. 2006 Apr 14;281(15):9845-51
references.pmid: 16459333
references.citation: Development. 2002 Mar;129(5):1131-41
references.pmid: 11874909
references.citation: Science. 1966 Dec 2;154(3753):1189-90
references.pmid: 17780042