Application:IP,WBClonality:PolyclonalHost:RabbitPurification:AmmoniumSulfateReactivity:Plant,ArABIdopsis,PeaBecauseplantshaveasessilelifestyle,theymustadjusttonumerousexternalstimuliandcoordinatetheirgrowthanddevelopmentaccordingly.Theplanthormones,agroupofstructurallyunrelatedsmallmolecules,arecentraltotheintegrationofdiverseenvironmentalcueswithaplant’sgeneticprogram.The‘classical’phytohormones,identifiedduringthefirsthalfofthetwentiethcentury,areauxin,abscisicacid,cytokinin,gibberellinandethylene.Morerecently,severaladditionalcompoundshavebeenrecognizedashormones,includingbrassinosteroids,jasmonate,salicylicacid,nitricoxideandstrigolactones.Plantsalsouseseveralpeptidehormonestoregulatevariousgrowthresponses,butthisclassofhormonesisbeyondourscopehere.Withtheapplicationofgeneticapproaches,mainlyinArabidopsisthaliana,manyaspectsofhormoneBIOLOGyhavebeenelucidated.Mosthormonesareinvolvedinmanydifferentprocessesthroughoutplantgrowthanddevelopment.Thiscomplexityisreflectedbythecontributionsofhormonesynthesis,transportandsignalingpathways,aswellasbythediversityofinteractionsamonghormonestocontrolgrowthresponses.Geneticscreensresultedintheidentificationofmanyoftheproteinsinvolvedinhormonesignalingandtheanalysisoftheseproteinshascontributedsignificantlytoourcurrentmodelsofhormoneaction.Oneparticularlyexcitingoutcomeistherecentidentificationofreceptorsforauxin,gibberellin,jasmonateandabscisicacid.Thoughfarfromcomplete,ourimprovedunderstandingofhormoneperceptionandsignalinghasallowedforcomparisonsbetweenhormones.Fromtheseitisclearthatsomehormones(cytokinins,ethyleneandthebrassinosteroids)usewell-characterizedsignalingmechanisms.Ontheotherhand,theidentificationandcharacterizationoftheauxinandjasmonatereceptors,aswellasproteinsingibberellinsignaling,havehighlightedanovelmechanismforhormoneperceptioninwhichtheubiquitin–proteasomepathwayhasacentralrole.[from:SantnerA.,MarkE.,Recentadvancesandemergingtrendsinplanthormonesignalling(2009)Nature459:1071-1078]Abscisicacid(ABA),atypeofplanthormone,isthoughttobeinvolvedintheinductionofdormancy,stomatalclosure,andphysiologicalfunctionssuchasflowerfallingandleaffalling.Thebiosynthesisofthissubstanceiscarriedoutbyoxidationofabscisinaldehyde,anditissuggestedthataspecificaldehydeoxidase(AO)catalyzesthereaction.TheCosmoBioAntibodyCollection(CAC)haspreparedthreeantibodiesfordetectingAOgeneproductsclonedfromArabidopsisthaliana,andanantibodyfordetectionofcornascorbicacidperoxidase(APT).Inhigherplantsaldehydeoxidases(AO)appeartobehomo-andheterodimericassembliesofAOsubunitswithprobablydifferentphysiologicalfunctions.AO-deltaseemstobeinvolvedinthelaststepofabscisicacidbiosynthesis,atleastinleavesandseeds.Invitro,AO-deltaoxidizesabscisicaldehydetoabscisicacid(ABA).Invitro,AO-deltaalsousesindole-3-aldehyde(IAld),benzaldehyde,1-naphthaldehydeandcinnamaldehydeassubstrate;theAAO2-AAO3dimeralsousesabscisicaldehydeassubstrate.Source:ProfessorKoichiKoshiba,TokyoMetropolitanUniversityGraduateSchoolofScienceandTechnologyDepartmentofLifeScienceReferences:Seo,M.,Koiwai,H.,Akaba,S.,Komano,T.,Oritani,T.,Kamiya,Y.andKoshiba,T.(2000)AbscisicaldehydeoxidaseinleavesofArabidopsisthaliana.PlantJ.23:481-488.