Morphogenesis in Nicotiana debneyi-tabacum, N. longiflora and their tumor-forming hybrid derivatives in vitro☆

[摘要] TheinterrelationshipsofphytohormonesingrowthandmorphogenesisofanewgroupofNicotianaspeciesandtheirhybridderivatives,tumorousandnontumorous,havebeeninvestigated.Stemtissuesfromthenontumor-formingspeciesNicotianadebneyi-tabacumandN.longifloradidnotgrowonHildebrandt'sbasalmediumsupplementedwith1%sucrose.Thisbasicmedium,ontheotherhand,supportedthegrowthofthetumorousderivatives(cytologicallycarryinganalienlongiflorachromosomeoritsfragmentinadditiontoacompletedebneyi-tabacumgenome),butnotthenontumorousderivativesofthesamepopulation.WhenthesegenotypeswereculturedonHildebrandt'sinorganicmediumsupplementedwith1%sucroseand15%coconutmilk(CMmedium),theyallgrew.However,theirmorphogeneticresponseswerestrikinglydifferentwithrespecttobudorrootformation.TissuesfromN.debneyi-tabacumconsistentlydifferentiatedrootsonly;N.longifloratissues,ontheotherhand,displayedexclusivebutweakbutformationontheCM.Thetumortissueconsistentlyandpredominantlydifferentiatedbuds,whereasnontumorderivativesofthesamepopulation(withoutthetumor-inducinglongiflorachromosome)formedonlyrootsliketheN.debneyi-tabacumparentintheCMmedium.ModifiedMurashigeandSkoog's(1962)medium(noaddedkinetinandIAA)permittedgrowthandpromotedbudsontumorpotentialstempieces,whiletissuefromtheparentspeciesandnontumorousderivativesdidnotgrow.Thediversemorphogeneticresponsessuggestedvariationinthebalanceofkininandauxin.Therefore,theresponseofthedifferentgenetictypesoftissuetoaddedIAAandkinetinonmodifiedMurashigeandSkoog'smediumwasstudied.TheresultsindicatedthatforthegrowthofthenontumortissuesIAAseemedtobeanabsoluterequirement.Atlowlevelsofaddedkinetintherewasenhancementofgrowth.Dependinguponthekinetin:IAAratiointhemedium,eitherbudsorrootscouldbeinducedinthesetissues.Tumortissue,ontheotherhand,didnotrequireeitherkinetinorIAAforitsgrowth,andremainedpredominantlyabudformeratlowkinetinand/orIAAconcentrations.Athigherconcentrationsofthesesubstancestherewaseitheramorphousgrowthorgrowthinhibitionofthetumortissue.Theinabilityofthetumortissuetodifferentiaterootsisthereforetoberelatedtoitsabnormalhormonemetabolism.

[学科分类] 生物科学（综合）