Comprehensive Natural Products II Vol.4 Chemical Ecology

659 Pages·2010·16.607 MB·English

by  Mander L., Liu H.-W.B.

4.01 Overview and Introduction
KenjiMori,TheUniversityofTokyo,Tokyo,Japan
ª2010ElsevierLtd.Allrightsreserved.
4.01.1 ScopeofVolume4 1
4.01.2 CommentsonProgressintheChemistryandBiologyofSemiochemicals 1
4.01.2.1 ProgressinStructureElucidation 1
4.01.2.2 ComplexityoftheMulticomponentPheromone 2
4.01.2.3 ProgressinUnravelingtheStereochemicalAspectsofChemicalEcology 3
4.01.2.4 DualRolesofSemiochemicalsasPheromonesandKairomones 4
4.01.2.5 NewTrendsinMammalianChemicalEcology 5
4.01.3 FuturePerspectivesinChemicalEcology 6
References 6
4.01.1 Scope of Volume 4
The present Volume 4 is a continuation of Volume 8 of the first edition,1 which summarizes progress in
chemicalecology.Chemicalecologyisanexpandingnewdisciplineinthestudyofchemistryandbiologyof
semiochemicalsorbiofunctionalmolecules,whichspreadsinformationamongindividuals.
Thisvolumetreatspheromones(Chapters4.04–4.06),defensivesubstancesandtoxins(Chapters4.08–4.10),
antifeedants (Chapters 4.11–4.12), compounds employed in plant-plant and plant-microbe interactions
(Chapter 4.13), plant-insect interactions (Chapter 4.14) and microbe-microbe interactions (Chapter 4.07).
Hormonesofplants(Chapter4.02)andinsects(Chapter4.03)arealsotreatedinthisvolume.Auniqueattempt
inthepresentvolumeistoregardflavorandfragrance(Chapter4.15)andtaste (Chapter4.16)asphenomenaof
human–environmentalinteractionsorhumanchemicalecology.
Consequently,allorganismsincludinghumanswillbetreatedinthelightofbioactivenaturalproducts.Inother
words,bioactivenaturalproductsrelatedtobiologicalindustriesincludingagriculture,forestry,fishery,foodindustry,
cosmeticsandpersonalcare,andfermentationindustrieswillbetreatedinthisvolume.Thetreatise,however,willbe
basictoincludechemistryinallaspectsofchemicalecology.ManyoftheapplicationsaretreatedinVolume3.
Prior to delving into the details, this overview briefly summarizes the recent progress made as follows:
(1) progress in structure elucidation, (2) complexity of the multicomponent pheromone, (3) stereochemical
aspectsofchemicalecology,(4)dualrolesofsemiochemicalssuchaspheromonesandkairomones,and(5)new
trendsinmammalianchemicalecology.
Theauthororiginallyreviewedthreeimportantaspectsofsemiochemicalresearchthathasbeendiscussed
in Volume 9. They are as follows: (1) determination of structure including the absolute configuration of
bioactive natural products, (2) problems of biological homochirality, and (3) study of structure–activity
relationshipstoinventmimicsofbioactivesmallmoleculessoastoutilizethemaspesticidesormedicinals.
Bergstro¨m2,3 recently published two excellent reviews on the birth and growth of chemical ecology as an
interdisciplinaryfield.Thesetworeviewsarerecommendedforthosewhowishtoknowthehistoryofchemical
ecologyoverthepast50years.
4.01.2 Comments on Progress in the Chemistry and Biology
of Semiochemicals
4.01.2.1 ProgressinStructureElucidation
Progressinmicroanalyticalmethodscontinuouslyimprovestheabilityofchemiststoclarifythestructuresof
new semiochemicals. In 2002, a new and revolutionary strategy in the structure determination of a biofunc-
tional and small molecule was reported by Hughson and coworkers.4 It was to determine the structure of a
1
2 OverviewandIntroduction
Figure1 Structuresofbioregulatorsofmicrobialorplantorigins.
biofunctionalmoleculeevenwithoutisolatingthecompounditself.Autoinducer-2(AI-2)isauniversalsignal
forinterspeciescommunication(quorumsensing)inbacteria,whichallowsthemtocoordinategeneexpression.
The structure of AI-2 remained elusive until 2002, when the X-ray crystallographic analysis of AI-2 sensor
protein(LuxPfrombioluminescentmarinebacteriumVibrioharveyi)inacomplexwithAI-2wassuccessfully
carried out.4 LuxP is the primary AI-2 receptor, and recombinant LuxP was overproduced in Escherichia coli
strainBL21.EightmilligramsofLuxP-AI-2complexwasnecessaryfortheX-raywork.AsshowninFigure1,
the bound ligand AI-2 was a furanosyl borate diester 1. The fact that the ligand contains boron could be
confirmedby11B-NMR(nuclearmagneticresonance)analysisofLuxP–AI-2complex.
This work demonstrates that we can determine the structure of a biofunctional molecule by isolating its
complex with a receptor protein, and analyzing the structure of the complex by X-ray. In case a receptor
protein is available in a sufficient amount by recombinant technology to make the complex crystalline,
Hughson’sstrategywillbetheidealwaytoelucidatethestructureofascarceandelusivebiofunctionalligand.
Inthepast,isolationofabioactivebutscarceligandanditsstructureelucidationwasaprerequisite,whichthen
enabledthedetectionandisolationofitsreceptorprotein.InHughson’sstrategy,thereceptorproteinwasthe
first target, and subsequently, the structure of its ligand was clarified. This is indeed a new method – the
so-called‘reversednaturalproductschemistry.’
Thesecondexampleofthestructureelucidationofanewsemiochemicalfollowedthetraditionalway,but
on a very small scale to isolate 18mg of target molecule 2, a factor inducing hyphal branching in arbuscular
mycorrhizal fungus Gigaspora margarita.5 Arbuscular mycorrhizal fungi form symbiotic associations with the
rootsofmore than80%ofland plants.Hostroots release asemiochemical that triggers hyphalbranching.In
2005,Akiyamaetal.5isolated5-deoxystrigol2(18mg)fromtherootexudatesofLotusjaponica,anddetermined
its structure by spectral [UV (ultraviolet), IR (infrared), 1H-NMR, EI-MS (mass spectrometry), and CD
(circular dichroism)] analysis and synthesis of ((cid:2))-2. They used activated charcoal to recover 2 from the
hydroponicsolutionofL.japonica.5-Deoxystrigol2elicitedhyphalbranchingofG.margaritaatconcentrations
rangingfrom1ngto1pgperdisc.Arelatedcompoundstrigol3hadbeenknownsince1966asagermination
stimulantfortheparasiticwitchweed,Strigalutea.
Through Akiyama’s work, strigolactones such as 2 and 3 were shown to be bioactive in two different
phenomenaintheplantkingdom,germinationofparasiticweedsandhyphalbranchinginarbuscularmycor-
rhizalfungi.Perhaps,theparasiticweedsusedtheplant’ssignalsforsymbiosiswithfungitofindouttheirhosts
forparasitism.
4.01.2.2 ComplexityoftheMulticomponentPheromone
In1959whenthefirstpheromonebombykol[(10E,12Z)-10,12-hexadecadien-1-ol]wasidentifiedasthefemale-
producedsex attractantofthesilkwormmoth Bombyxmori,thepheromonalactivitywasthought tobetotally
due to that single compound.6 At present, it is generally believed that a pheromone is composed of many
pheromone components (see Chapter 4.04), which resembles the present concept in flavor and fragrance
chemistry, that is, to consider a mixture as a whole to be responsible for a particular sense of smell (see
Chapter4.15).
Recently in 2008, Lacey et al.7 reported a typical example showing the complexity of a multicomponent
pheromone.Amale-producedaggregationpheromoneofthecerambycidbeetleMegacyllenecaryaecontainedas
OverviewandIntroduction 3
Figure2 Componentsofthemale-producedaggregationpheromoneofthecerambycidbeetleMegacyllenecaryae.
Percentcompositionsareindicatedwithinparentheses.
many as eight male-specific compounds as shown in Figure 2. They are (2R,3S)-2,3-hexanediol 4, its
enantiomer (2S,3R)-2,3-hexanediol 4, (S)-limonene 5, 2-phenylethanol 6, (S)-(cid:2)-terpineol 7, nerol 8, neral 9,
andgeranial10.7Noneofthesecompoundswasattractiveasasinglecomponent.BothsexesofM.caryaewere
attractedtothecompleteblendoftheseeightcompounds,buttheeliminationofanyoneofthemresultedina
decreased trap capture. Blends that were missing such as (2S,3R)-4, (2R,3S)-4, or a mixture of 9 and 10 (1:1)
werepheromonallyinactive.Modernstudiesonsemiochemicalsrevealedtheimportanceofapropermixture
toevokeabiologicalreaction.
4.01.2.3 ProgressinUnravelingtheStereochemicalAspectsofChemicalEcology
The author’s overview in Volume 8 of CONAP (first edition) briefly treated the relationship between
stereochemistry and pheromone activity among insects.1 The significance of chirality in pheromone science
wasalsodiscussedindepthbytheauthorin2007.8Furtherexampleswerereportedtoshowtheimportanceof
chiralityinchemicalcommunicationsamongmicroorganisms9,10andmammals.11Themicrobialcaseswillbe
summarizedinthissection.
Fungi in the genus Phytophthora are destructive phytopathogens, and caused the well-known Irish potato
faminein1840s.Afactorknownashormone(cid:2)1issecretedbytheA1matingtypeofPhytophthoranicotianae,and
inducestheformationofsexualsporesintheA2matingtype.Byisolating1.2mgofthehormone(cid:2)1from1830l
ofculturebrothofP.nicotianae,itsstructurewasproposedas(15R)-11showninFigure3.Theconfigurationsat
theotherthreestereogeniccentersremainedobscure.Interestingly,11induces sexualsporeformationinthe
A2matingtypesofseveralotherspeciesinthegenusPhytophthora,andtherefore11isauniversalmatingsignal
in the heterothallic species of Phytophthora. In order to determine the absolute configuration of hormone (cid:2)1,
Yajimaetal.9synthesizedandbioassayedvariousstereoisomersof11.Theonlybioactivestereoisomeratadose
of10ngwas(3R,7R,11R,15R)-11,whichmustthereforebethenaturalhormone(cid:2)1.
4 OverviewandIntroduction
Figure3 Structuresofmicrobialsemiochemicals.
N-Acyl homoserine lactones (AHLs) are important pheromones controlling quorum sensing among
Gram-negativebacteria.AnAHLcalledsmallbacteriocinpossessesthestructure(2S,39R,79Z)-12asshownin
Figure3,andisthequorum-sensingpheromoneofanitrogenfixerRhizobiumleguminosarumlivinginsymbiosis
with leguminous plants. Yajima’s synthesis of 12 and its stereoisomers enabled the examination of the
stereochemistry–bioactivityrelationshipsinthecaseofsmallbacteriocin.10Thenatural(2S,39R,79Z)-12exhib-
ited the greatest bioactivity, whereas the other three stereoisomers showed 5–500 times weaker bioactivity.
Chiralitywasshowntobealsoimportantforchemicalcommunicationsamongbacteria.
4.01.2.4 DualRolesofSemiochemicalsasPheromonesandKairomones
Ithasbeenbelievedthatpheromonesactonlyaspheromonesofacertainspecies.Recentstudieshaverevealed
thatpheromonesactalsoaskairomonesforthepredatorsagainstthepheromonereleasers.Twoexamplesare
givenbelow.
ThescarabbeetleOsmodermaeremitaanditslarvalpredator,theclickbeetleElaterferrugineus,areknownas
indicators of the species richness of insect fauna of hollow deciduous trees in Northern Europe. (R)-4-
Decanolide 13 (Figure 4) is the male-produced sex pheromone of O. eremita.12 Lactone 13 is also employed
byE.ferrugineusasakairomoneforthedetectionoftreehollowscontainingthelarvaeofO.eremita.12
Dunkelblum and coworkers,13,14 in association with the author’s group, studied both the pheromonal and
kairomonal activities of three female-produced sex pheromones 14–16 of the pine bast scales of Matsucoccus
speciestogetherwiththeiranalogues17and18.TheIsraelipinebastscale,M.josephi,employs(2E,5R,6E,8E)-
14 as its sex pheromone, whereas (3S,7R,8E,10E)-15 is used by M. feytaudi and (2E,4E,6R,10R)-16 by
M. matsumurae. The pheromone 14 was found to be a potent kairomone for Elatophilus hebraicus adults, the
Figure4 Structuresofinsectpheromonesandtheirmimicstoillustratethepheromone–kairomonerelationship.
OverviewandIntroduction 5
majorpredatorybugagainstM.josephi.Strangelyenough,theIsraelipredatorE.hebraicuswasalsoattractedby
15and16,althoughbothM.feytaudiandM.matsumuraeareabsentinIsrael.Itseemsasifthepresenceofthe
dienemoietyof14–16issufficienttoattracttheadultE.hebraicus.Thekairomonalactivityof14–16isageneral
phenomenon,andM.feytaudipheromoneattractspredatorssuchasElatophiluscrassicornisandHemerobiusstigma
inPortugalandE.nigricornisandH.stigmainItalyandFrance.
The pheromone analogues 17 and 18 showed interesting biological properties. The nor-analogue 17 of
M.josephipheromone14preservedthepheromonalactivitybuteliminateditskairomonalactivity.13Similarly,
theremovaloftheterminalmethylgroupfromthedienemoietyof15,producingthenor-analogue18,again
preserveditspheromonalactivitybuteliminatedthekairomonalactivity.14Thus,subtleanddesignedaltera-
tions in the structure of the diene system change the mode of the kairomonal activity markedly. The two
mimics17and18maybeusefultocaptureonlythepestpinebastscaleswithoutdisturbingtheirpredators.
4.01.2.5 NewTrendsinMammalianChemicalEcology
Asthescienceofinsectpheromoneshasfullydeveloped,studiesonthepheromonesofmammalsandaquatic
organisms are now gaining popularity among scientists. Two examples involving acetal pheromones in
mammals are discussed. As can be seen in the pheromone chapter of Francke and Schulz, acetals have been
knownoriginallyasaggregationpheromonesofbarkbeetles(Chapter4.04).
According to Rasmussen’s recent study, the male Asian elephants, Elephas maximus, release frontalin 19
(Figure5)fromthetemporalglandonthefaceduringmusth,whichisanannualperiodofsexualactivityand
aggression.11Theratiooffrontalinenantiomersenablesotherelephantstodistinguishboththematurityofmale
elephants in musth and the phase ofmusth.In young males, significantly more (1R,5S)-(þ)-frontalin 19than
(1S,5R)-((cid:3))-frontalin19isreleased.Astheelephantreachesmaturity,theratiobecomesalmostequaltoemit
((cid:2))-frontalin.Musthperiodsgetlongerasmalesage.Secretionscontaininghighconcentrationoffrontalin19at
racemicratiosattractedfollicular-phasefemales,whereasthesecretionsrepulsedmalesaswellaslutealphase
andpregnantfemales.Theimportanceoftheenantiomericcompositionoffrontalin19inthebehaviorofAsian
elephantswasobservedonlyaftertheadventofenantioselective(chiral)gaschromatography(GC).Itshouldbe
notedthatbarkbeetlesemploy(1S,5R)-((cid:3))-frontalin19astheirpheromonecomponent.
Genes in the major histocompatibility complex (MHC), known for their role in immune recognition and
transplantationsuccess,areinvolvedinmodulatingmatechoiceinmiceandperhapsalsoinhumans.15Volatile
bodyodorsofmiceareregulatedbyMHCgenes,anditistheseodordifferencesthatunderlinematechoiceand
familialrecognition.Anindividual’solfactoryidentityiscodedinpartbyapatternofvolatilesemiochemicals,
whichisregulatedbygenesinMHC.16Inthisconnection,theeffectsofmicepheromonecomponentsonthe
attractivenessofamalemouseevolvedasaninterestingresearchtopic.Forthisstudy,previouslysynthesized
micepheromonecomponents20and2117aswellasnewlysynthesizedones22and2318wereemployed.
Inmanywildanimals,oldermalesareoftenpreferredbyfemales,becausetheycarry‘good’genesthataccount
for their viability. In the case of mice, Mus musculus, higher levels of (1R,5S,7R)-dehydro-exo-brevicomin 20
Figure5 StructuresofpheromonecomponentsofmaleAsianelephantsandmice.
6 OverviewandIntroduction
(exo-brevicomin is a bark beetle pheromone) and (S)-2-sec-butyl-4,5-dihydrothiazole 21 and 2-isopropyl-4,5-
dihydrothiazole22weredetectedintheurine of aged malemice than innormal adultmales, whereasalower
levelof6-hydroxy-6-methyl-3-heptanone23wasobserved.19When20–22were addedtotheurine ofnormal
adultmales,theirurineshowedanenhancedattractivenessagainstfemalemice.Theadditionof23hadnoeffect
atall.Accordingly,itisestablishedinthecaseofmicethatsemiochemicalscontrolthemateselectionprocess.19A
search to understand the role of semiochemicals in higher animals including humans will continue to be an
interestingareaofchemicalecologywithpotentialimpactonperfumeindustries.
4.01.3 Future Perspectives in Chemical Ecology
In order to preserve our global ecological system, we require an in-depth knowledge in chemical ecology to
understandmoreabouttheroleofbioactivenaturalproductsintheenvironment.Thiswillenableustoresolve
manyproblemsthatremainunraveled.Chemicalecologyisaninterdisciplinarysciencebetweenchemistryand
biology.Noonecanbeanexpertinboththeareasunlessonewantstoremainsuperficial.Thus,thiscallsusto
rememberthefollowingwordsoftheApostlePaul:‘‘Thepersonwhothinksheknowssomethingreallydoesnot
knowasheoughttoknow(1Corinthians8:2).’’ThissentencewasalsocontainedinVolume9Chapter5.
Acknowledgments
IwishtothankDr.T.Tashiroforhishelp.
Glossary
kairomone Akairomoneisachemicalsubstanceproducedandreleasedbyalivingorganismthatbenefitsthe
receiveranddisadvantagesthedonor.Thekairomoneimprovesthefitnessoftherecipientandinthisrespect
differsfromanallomone.
References
1. K. Mori, Ed., Comprehensive Natural Products Chemistry, Vol. 8: Miscellaneous Natural Products including Marine Natural
Products,Pheromones,PlantHormones,andAspectofEcology,Elsevier:Oxford,1999;pp1–749.
2. G.Bergstro¨m,PureAppl.Chem.2007,79,2305–2323.
3. L.G.W.Bergstro¨m,Chem.Commun.2008,3959–3979.
4. X.Cheng;S.Schauder;N.Potier;A.VanDorsselaer;I.Pelczer;B.L.Bassler;F.M.Hughson,Nature2002,415,545–549.
5. K.Akiyama;K.Matsuzaki;H.Hayashi,Nature2005,435,824–827.
6. A.Butenandt;R.Beckmann;D.Stamm;E.Hecker,Z.Naturforsch.1959,14b,283–284.
7. E.S.Lacey;J.A.Moreira;J.G.Millar;L.M.Hanks,J.Chem.Ecol.2008,34,408–417.
8. K.Mori,Bioorg.Med.Chem.2007,15,7505–7523.
9. A.Yajima;Y.Qin;X.Zhou;N.Kawanishi;X.Xiao;J.Wang;D.Zhang;Y.Wu;T.Nukada;G.Yabuta;J.Qi;T.Asano;Y.Sakagami,
Nat.Chem.Biol.2008,4,235–237.
10. A.Yajima;A.A.N.vanBrussel;J.Schripsema;T.Nukada;G.Yabuta,Org.Lett.2008,10,2047–2050.
11. D.R.Greenwood;D.Comeskey;M.B.Hunt;L.E.L.Rasmussen,Nature2005,438,1097–1098.
12. G.P.Svensson;M.C.Larsson,J.Chem.Ecol.2008,34,189–197.
13. S.Kurosawa;M.Takenaka;E.Dunkelblum;Z.Mendel;K.Mori,ChemBioChem2000,1,56–66.
14. Z.Mendel;E.Dunkelblum;M.Branco;J.C.Franco;S.Kurosawa;K.Mori,Naturwissenschaften2003,90,313–317.
15. K.Yamazaki;G.K.Beauchamp,Adv.Genet.2007,59,129–145.
16. G.K.Beauchamp;K.Yamazaki,Biochem.Soc.Trans.2003,31(Part1),147–151.
17. T.Tashiro;K.Mori,Eur.J.Org.Chem.1999,2167–2173.
18. T.Tashiro;K.Osada;K.Mori,Biosci.Biotechnol.Biochem.2008,72,2398–2402.
19. K.Osada;T.Tashiro;K.Mori;H.Izumi,Chem.Senses2008,33,815–823.
OverviewandIntroduction 7
BiographicalSketch
KenjiMoriwasbornin1935andhasspentatotalof42yearsattheUniversityofTokyo.He
obtained aB.Sc. degree in agricultural chemistry(1957), followed by an M.Sc.in biochem-
istry(1959),andPh.D.inorganicchemistry(1962).Hewasthenappointedassistant(1962),
associate professor (1968), and served as a professor of organic chemistry (1978) at the
UniversityofTokyountil1995.Heisnowprofessoremeritus.Dr.Moriworkedfor7years
(1995–2001) as aprofessor at the Science University of Tokyo. At present, he is a research
consultantatRIKEN(InstituteofPhysicalandChemicalResearch)andatToyoGoseiCo.,
Ltd.HewasawardedtheJapanAcademyPrize(1981),theSilverMedaloftheInternational
Society of Chemical Ecology (1996), the American Chemical Society’s Ernest Guenther
Award in the Chemistry of Natural Products (1999), the Special Prize of the Society of
SyntheticOrganicChemistry,Japan(2003),andtheFrantisekSormMemorialMedalofthe
AcademyoftheCzechRepublic(2003).
4.02 Plant Hormones
IsomaroYamaguchi,MaebashiInstituteofTechnology,Gunma,Japan
JerryD.CohenandAngelaH.Culler,UniversityofMinnesota,Minneapolis,USA
MarcelQuint,LeibnizInstituteofPlantBiochemistry,Halle,Germany
JanetP.Slovin,UnitedStatesDepartmentofAgriculture,Washington,DC,USA
MasatoshiNakajima,TheUniversityofTokyo,Tokyo,Japan
ShinjiroYamaguchi,HitoshiSakakibara,andTakeshiKuroha,RIKENPlantScienceCenter,
Kanagawa,Japan
NobuhiroHirai,KyotoUniversity,Kyoto,Japan
TakaoYokota,TeikyoUniversity,Utsunomiya,Japan
HiroyukiOhtaandYuichiKobayashi,TokyoInstituteofTechnology,Tokyo,Japan
HitoshiMoriandYojiSakagami,NagoyaUniversity,Nagoya,Japan
ª2010ElsevierLtd.Allrightsreserved.
4.02.1 Introduction 12
4.02.2 Auxins 13
4.02.2.1 Introduction 13
4.02.2.2 Chemistry 14
4.02.2.2.1 IAAconjugatesinplants 14
4.02.2.2.2 IAApeptideconjugates 14
4.02.2.2.3 Aminoacidconjugates 14
4.02.2.2.4 Amideconjugatehydrolysis 15
4.02.2.2.5 Esterconjugates 15
4.02.2.3 BiosynthesisandMetabolism 16
4.02.2.3.1 Tryptophan-independentbiosynthesis 17
4.02.2.3.2 Tryptophan-dependentpathways 17
4.02.2.3.3 IAAdegradation 22
4.02.2.4 PerceptionandSignaling 22
4.02.2.4.1 Transcriptionalresponsestoauxinstimuli 22
4.02.2.4.2 Regulationofauxinresponsebytheubiquitinpathway 24
4.02.2.4.3 Auxinreceptors 24
4.02.3 Gibberellins 24
4.02.3.1 Introduction 24
4.02.3.2 Chemistry 25
4.02.3.2.1 Fungalgibberellins 25
4.02.3.2.2 Plantgibberellins 26
4.02.3.2.3 Isolationandcharacterization 26
4.02.3.2.4 Qualitativeandquantitativeanalysis 27
4.02.3.3 BiosynthesisandMetabolism 27
4.02.3.3.1 Biosynthesisinplants 27
4.02.3.3.2 Deactivationinplants 30
4.02.3.3.3 Regulationofgibberellinlevelsinplants 30
4.02.3.3.4 Biosynthesisinfungi 31
4.02.3.4 BiologicalActivities 32
4.02.3.4.1 Effectsonshootelongation 32
4.02.3.4.2 Effectsonenzymeactivitiesandinductions 33
4.02.3.4.3 Effectsonflowering 33
4.02.3.4.4 Othereffects 33
9
10 PlantHormones
4.02.3.5 PerceptionandSignaling 34
4.02.3.5.1 OverviewofGAsignalinginplants 34
4.02.3.5.2 GID1,thecytosolicgibberellinreceptor 34
4.02.3.5.3 DELLAprotein,akeyregulatorofGAsignaling 36
4.02.3.5.4 F-boxprotein,recruiterofDELLAforitsdegradation 37
4.02.4 Cytokinins 37
4.02.4.1 Introduction 37
4.02.4.2 Chemistry 37
4.02.4.2.1 Structures 37
4.02.4.3 BiosynthesisandMetabolism 40
4.02.4.3.1 Twopathwaysforisoprenoidcytokininbiosynthesis 40
4.02.4.3.2 Cytokininbiosynthesisinmicroorganisms 40
4.02.4.3.3 Cytokininbiosynthesisinhigherplants 40
4.02.4.3.4 CytokininproductionbydegradationoftRNA 42
4.02.4.3.5 IPTinPhyscomitrellapatens 42
4.02.4.3.6 Metabolicoriginsofisoprenoidsidechains 42
4.02.4.3.7 Activationstepofcytokininbiosynthesis 42
4.02.4.3.8 Modificationofisoprenoidsidechain 43
4.02.4.3.9 Modificationofadeninemoiety 46
4.02.4.3.10 Degradationofcytokinins 46
4.02.4.4 Translocation 47
4.02.4.5 BiologicalActivities 48
4.02.4.5.1 Delayofleafsenescence 48
4.02.4.5.2 Controlofthecellcycle 48
4.02.4.5.3 Controlofshootmeristemactivity 48
4.02.4.5.4 Controlofrootmeristemactivity 49
4.02.4.5.5 Regulationofvasculardevelopment 49
4.02.4.5.6 Releaseofbudsfromapicaldominance 49
4.02.4.5.7 Regulationofrootformation 49
4.02.4.5.8 Regulationofnoduleformation 50
4.02.4.5.9 Interactionsbetweenmacronutrientsandcytokinins 50
4.02.4.6 PerceptionandSignaling 51
4.02.4.6.1 Cytokinin-bindingproteins 51
4.02.4.6.2 Cytokininreceptorasahistidineproteinkinase(His-kinase) 51
4.02.4.6.3 Phosphotransferproteins 52
4.02.4.6.4 Responseregulators 53
4.02.4.6.5 Branchofthetwo-componentpathway 53
4.02.5 AbscisicAcid 53
4.02.5.1 Introduction 53
4.02.5.2 Chemistry 54
4.02.5.2.1 Isolationandanalysis 54
4.02.5.2.2 Physicochemicalproperties 55
4.02.5.2.3 Structure–activityrelationship 58
4.02.5.3 BiosynthesisandMetabolism 60
4.02.5.3.1 Biosynthesisinplants 60
4.02.5.3.2 Biosynthesisinfungi 62
4.02.5.3.3 Metabolism 63
4.02.5.4 BiologicalActivities 65
4.02.5.4.1 Stomatalclosure 65
4.02.5.4.2 Inhibitionofseedgerminationandotheractivities 66
4.02.5.4.3 ReceptorsofABAandABA-relatedgenesandproteins 66
PlantHormones 11
4.02.6 Brassinosteroids 67
4.02.6.1 Introduction 67
4.02.6.2 Chemistry 68
4.02.6.2.1 Distribution 68
4.02.6.2.2 Structure 68
4.02.6.2.3 Analysis 68
4.02.6.2.4 Synthesis 70
4.02.6.2.5 Structure–activityrelationship 70
4.02.6.3 BiosynthesisandMetabolism 72
4.02.6.3.1 Biosynthesisofcastasterone 72
4.02.6.3.2 Biosynthesisofbrassinolidefromcastasterone 75
4.02.6.3.3 Regulationofbiosynthesis 75
4.02.6.3.4 Metabolismanditsregulation 75
4.02.6.4 PhysiologyandSignalTransduction 75
4.02.6.4.1 Physiology 75
4.02.6.4.2 Signaltransduction 76
4.02.7 JasmonatesandOxylipins 77
4.02.7.1 Introduction 77
4.02.7.2 Chemistry 78
4.02.7.2.1 Chemicalstructure 78
4.02.7.2.2 Chemicalstability 79
4.02.7.2.3 Chemicalsynthesisofthemetabolitesonthelinolenicacidcascade 79
4.02.7.3 BiosynthesisandMetabolism 83
4.02.7.3.1 Biosyntheticpathwayinplants 83
4.02.7.3.2 Lipid-derivedreactiveelectrophilespeciesandnonenzymaticallyformedoxylipins 84
4.02.7.4 Physiology 84
4.02.7.4.1 Responsestobioticandabioticstresses 84
4.02.7.4.2 Stressresponseintheabsenceofjasmonicacid 85
4.02.7.4.3 Effectofjasmonatesondevelopmentalprocesses 85
4.02.7.4.4 OPDAondevelopmentalprocesses 86
4.02.7.5 Signaling 86
4.02.8 Ethylene 87
4.02.8.1 Introduction 87
4.02.8.2 Chemistry 87
4.02.8.3 Biosynthesis 87
4.02.8.3.1 TranscriptionalregulationofACCsynthase 88
4.02.8.3.2 PosttranslationalregulationofACCsynthase 88
4.02.8.4 PerceptionandSignaling 89
4.02.8.4.1 Ethylenereceptors 89
4.02.8.4.2 RTE1/GR 90
4.02.8.4.3 CTR1 90
4.02.8.4.4 EIN2 90
4.02.8.4.5 EIN3 90
4.02.9 PeptideHormonesinPlants 91
4.02.9.1 Introduction 91
4.02.9.2 Systemins 91
4.02.9.3 AtPep1 92
4.02.9.4 Phytosulfokine 93
4.02.9.5 RegulatoryFactorsforSelf-Incompatibility 94
4.02.9.6 MCLV3andCLEPeptides 94
4.02.9.7 OtherPeptides 95
4.02.9.8 Remarks 95