植物表观遗传.ppt

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1、PlantEpigeneticsGregorMendel(1822-1884)FatherofGenetics,discoveredthebasiclawsofheredity.ThomasHuntMorgan(1966-1945)Discoveredthe3rdbasicgeneticlaw,togetherwithMendel’stwolaws,theyformthebasisofwhatisnowknownasclassicalgenetics.Elucidationofthe“doublehelixstru

2、cture”ofDNAmoleculeisoneofthemostimportantscientificdiscoveryinthe20thcentury,whichsymbolsthebirthofMolecularGenetics.JamesWatson&FrancisCrickMendelianGeneticsAlterationingeneexpressionand/orfunctionNovelphenotypeChangeinnucleotidesequenceMonozygoustwinssharea

3、commongenotypeandaregeneticallyidenticalThereissignificantphenotypicdiscordance:MentaldisordersCancerDNAIsNotDestinyThecellsaregeneticallyidentical,butdifferent!Whatisepigenetics?*Thesechangesmayremainthroughcelldivisionsfortheremainderofthecell'slifeandmayals

4、olastformultiplegenerations.*EpigenomeprovidesinstructionsandregulatesthefunctionalaspectsofallthegenesAllheritablechangesingeneexpressionandchromatinorganizationthatareindependentoftheDNAsequenceitself.DevelopmentanddifferentiationMaintenanceofcellularidentit

5、y*‘On’or‘over’thegeneticinformationencodedintheDNAEpigeneticsvsGeneticsComponentsA:Nucleosome*Position*Chromatinaccessibility*HigherorderchromatininteractionsB:HistonemodificationsC:DNAmethylationD:Non-codingRNA(e.g.microRNA)CH »CH3CH3AcMeNH3H2AH2BH4NAcMeNucle

6、osomepositioningHistonevariantdepositionDNAmethylationHistonemodification&recognitionNoncodingRNAEpigeneticinformationsChromosomesconsistofheterochromatinandeuchromatinDenselypackagedheterochromatinLessdenselypackagedeuchromatinDNAaroundthecentromereisusuallyp

7、ackagedasheterochromatin.CENTROMEREEffectsonreplication,recombination,repair,andtranscriptionDNAmethylationInestablishingheterochromatin,whichisthedrivingforce–DNAmethylation?-Histonemodification?NucleosomeLocationofanucleosomeMultipleisoformsofthehistonesCova

8、lenthistonemodificationsWherearethenucleosomesinplants?Nucleosomeoccupancyandpositioningarecriticaltobiologicaloutcomes,primarilybecausenucleosomesinhibittheaccessofotherDNA-bindin