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1、第八章第八章生物技术保鲜生物技术保鲜植物采后腐败植物采后腐败 n nNumberofefficientchemicalandphysicalNumberofefficientchemicalandphysicaltreatmentscanbeusedtopreservefreshfoodstreatmentscanbeusedtopreservefreshfoodsn nIdealwaytopreservefoods(plant)Idealwaytopreservefoods(plant)GeneticallyprogrammetofoodstodothejobGeneticallyprogr
2、ammetofoodstodothejobbythemselveswithanyhumaninterventionbythemselveswithanyhumaninterventionn nOnceplanttissuesareharvested,theyOnceplanttissuesareharvested,theyengageinanacceleratedsenescenceengageinanacceleratedsenescenceprocessthatleadstospoilageprocessthatleadstospoilagen nPlantorgansenescenceP
3、lantorgansenescence NaturalprocessNaturalprocess ControlledbygeneControlledbygenen nHarvestingdetachingorgansfrommainHarvestingdetachingorgansfrommainplantsplantsn nAddingastrongstresscomponentspeedingAddingastrongstresscomponentspeedingupthedecayupthedecayn nGeneticengineeringhasthepotentialtoslowd
4、ownthenaturalsenescenceprocessesandalleviatethestressresponsesfromharvestedtissues水果的分类水果的分类n nTowmajorclassesofunprocessedplantfoodstuffsn nClimactericn nNon-climacteric n nBasedonBasedon WhetherornotexhibitarespiratoryriseattheWhetherornotexhibitarespiratoryriseattheonsetofsenescenceaccompaniedbya
5、nauto-onsetofsenescenceaccompaniedbyanauto-catalyticproductionofethylenecatalyticproductionofethyleneTheclimactericpatternofrespirationinclimactericfruits跃变型果实跃变型果实n nEthyleneplayimportantroleinripeningEthyleneplayimportantroleinripeningn nOnripening,largeincreaseinethyleneOnripening,largeincreasein
6、ethyleneproductionandsensitivetoethyleneproductionandsensitivetoethylenen nExposuretoethyleneaccelerateripeningExposuretoethyleneaccelerateripeningn nPracticalproblemsduringtransportandPracticalproblemsduringtransportandstoragestoragePresenceofotherripeningfruitswillactinPresenceofotherripeningfruit
7、swillactinasynergisticwaytoacceleratesenescenceasynergisticwaytoacceleratesenescenceSome Climacteric&Non-climacteric fruits&vegetablesClimactericClimactericNon-climactericNon-climactericAppleAppleNectarineNectarineGrapeGrapeApricotApricotPapayaPapayaPineapplePineappleBananaBananaPeachPeachOrangeOran
8、geMangoMangoPearPearStrawberryStrawberryVegetableVegetableTomatoTomatoCucumberCucumberFruit成熟中的变化成熟中的变化n nClimactericClimacteric ChemicalchangesChemicalchangesn nSugar,nutritionalcompounds,color,tasteSugar,nutritionalcompounds,color,tasten nNarrowtimeNarrowtime StructureStructuren nNon-climactericNo
9、n-climacteric EffectofethyleneislittleEffectofethyleneislittle MostprocessisidenticalMostprocessisidentical乙烯生物合成途径乙烯生物合成途径 Methionine(Met)SAMACCEthylene(C2H4)ACC synthase(ACS)ACC oxidase(ACO)AdoMet synthetaseSAM,S-adenosyl methionine;ACC,1-aminocyclopropane-1-carboxylic acidTransgenic tomatoesNon-r
10、ipening Ripening (2)Manipulating ACO n nACOACO FinalenzymeonthebiosyntheticpathwayFinalenzymeonthebiosyntheticpathwayn nAntisensegeneofACOintomatoAntisensegeneofACOintomato ReducedlevelsofethyleneReducedlevelsofethylene ExtendedripeningperiodExtendedripeningperiodn nRipeningwasdelayedbythesuppressio
11、nofRipeningwasdelayedbythesuppressionoftheACCoxidasegenetheACCoxidasegene(3)Depletion of SAM and ACC n nBacterialgenecodingACCdeaminaseBacterialgenecodingACCdeaminase(脱氨基酶脱氨基酶)tomatotomato EthylenereducedEthylenereduced FirmnessincreasedFirmnessincreasedn nAgeneencodingSAMhydrolaseAgeneencodingSAMhy
12、drolasetomatotomato EthylenereducedEthylenereduced FruitstayedfirmerFruitstayedfirmer(4)Inhibition of ethylene receptor n nEthyleneisperceivedbythecellbyafamilyEthyleneisperceivedbythecellbyafamilyofreceptorsofreceptorsn nSuccessSuccess SuppresstheexpressionofNr(CSuppresstheexpressionofNr(C2 2H H4 4
13、receptor)receptor)FruitswithverylowlevelsoftheNrgeneFruitswithverylowlevelsoftheNrgeneexpressionshoweddelayedripening.expressionshoweddelayedripening.Non-climacteric fruits n nLittleisknownaboutthemechanismsLittleisknownaboutthemechanismscontrollingfruitripeningcontrollingfruitripeningn nEconomicimp
14、ortanceEconomicimportancen nImportantagronomictrait:firmnessImportantagronomictrait:firmnessn nRipeningusuallyaccompaniedbyincreaseofRipeningusuallyaccompaniedbyincreaseofsofteningsoftening ManipulationoffruitfirmnesscanleadtolongerManipulationoffruitfirmnesscanleadtolongereffectiveperiodofconsumera
15、cceptabilityandeffectiveperiodofconsumeracceptabilityandreducedlossesreducedlossesManipulation of fruit firmness -the case of strawberryn nTransgenicstrawberryplantsTransgenicstrawberryplants Fruit-ripening-specificpectatelyase(Fruit-ripening-specificpectatelyase(果胶裂解酶果胶裂解酶)genehadbeensilenced)geneh
16、adbeensilencedn nNodifferencewasobservedinNodifferencewasobservedin color,shapeorweightcolor,shapeorweightn nCleardifferenceinfirmnessCleardifferenceinfirmnessn nMicroscopicanalysisofthefruitsMicroscopicanalysisofthefruits cellwallsintransgenicfruitsdisplayedalowercellwallsintransgenicfruitsdisplaye
17、dalowerdegreeofswellingthancontrolfruitsdegreeofswellingthancontrolfruits3.Methods for reducing spoilage in vegetables n nEdiblevegetablescomeinallshapes,Ediblevegetablescomeinallshapes,developmentalstagesandcolorsdevelopmentalstagesandcolorsn nLeafyvegetablesarethemosteconomicallyLeafyvegetablesare
18、themosteconomicallyimportanttypeimportanttype LettuceLettuceletisletis SpinachSpinach EndiveEndiveendaiv endaiv 菊莴苣菊莴苣菊莴苣菊莴苣 RadicchioRadicchio菊苣菊苣 WitloofWitloof菊苣菊苣 Reducing spoilage in vegetables n nEthylenereceptorEthylenereceptor EthyleneisintimatelylinkedtosenescenceanditsEthyleneisintimatelyl
19、inkedtosenescenceanditsroleasasenescenceinducerhasbeenfirmlyroleasasenescenceinducerhasbeenfirmlyestablishedestablished EthyleneinsensitiveplantsEthyleneinsensitiveplantsn nMutagenizeMutagenize（诱变）（诱变）todisruptethyleneperceptiontodisruptethyleneperceptionCytokinins(细胞分裂素细胞分裂素)n nAntagonistictoethyle
20、neAntagonistictoethylenen ndelayingtheonsetofsenescenceinleavesdelayingtheonsetofsenescenceinleavesn nDuringthesenescenceprocess,thereisaDuringthesenescenceprocess,thereisadropincytokininlevelsdropincytokininlevelsn nmanipulatecytokininbiosynthesistodelaymanipulatecytokininbiosynthesistodelaysenesce
21、nceinleavessenescenceinleaves BacterialgenecodingforenzymeforBacterialgenecodingforenzymeforbiosynthesisofcytokininsbiosynthesisofcytokinins CytokininslevelelevatedCytokininslevelelevated DelayinleafsenescenceDelayinleafsenescencen nTransgenicbroccoliTransgenicbroccoli carryingantisensecopiesofatoma
22、toACOgenecarryingantisensecopiesofatomatoACOgene Ethylenelowerthancontrols(72hafterEthylenelowerthancontrols(72hafterharvesting)harvesting)Respirationratedecrease(98hafterharvest)Respirationratedecrease(98hafterharvest)4.Enhancing plant resistance to fungal and bacteria n nOneofthemostpromisingresis
23、tanceOneofthemostpromisingresistancestrategiesstrategies useofcellwalllyticenzymestodegradeoruseofcellwalllyticenzymestodegradeordamagethefungalcellwalldamagethefungalcellwall Majorcomponents:chitinandglucanMajorcomponents:chitinandglucann nSeveralkindsofchitinasesandglucanasesSeveralkindsofchitinas
24、esandglucanaseshavenowbeenclonedhavenowbeenclonedn ntransgenicplantstransgenicplants anincreaseddegreeofresistancetofungalanincreaseddegreeofresistancetofungalpathogenspathogensn nbacterialresistanceisdifficulttoaccomplishbacterialresistanceisdifficulttoaccomplishSafety of Transgenic Foods/GMO/GEOn
25、nFDA1992Federal Register statementTheagencyisnotawareofanyinformationTheagencyisnotawareofanyinformationshowingthatfoodsderivedbythesenewshowingthatfoodsderivedbythesenewmethodsdifferfromotherfoodsinanymethodsdifferfromotherfoodsinanymeaningfuloruniformway,orthat,asameaningfuloruniformway,orthat,asa
26、class,foodsdevelopedbythenewtechniquesclass,foodsdevelopedbythenewtechniquespresentanydifferentorgreatersafetypresentanydifferentorgreatersafetyconcernthanfoodsdevelopedbytraditionalconcernthanfoodsdevelopedbytraditionalplantbreeding.plantbreeding.Regulatory process for transgenic crops in the U.S.n
27、 nInstitutional Biosafety Committeen nAnimal and Plant Health Inspection Service(APHIS)of USDAn nFood and Drug Administration(FDA)n nEnvironmental Protection Agency(EPA)GM Food Label Requiredn nEuropeanUnionsEuropeanUnions 10/2003:Labeling&traceability10/2003:Labeling&traceability 04/2004:EC1829/200
28、3&EC1830/200304/2004:EC1829/2003&EC1830/2003n nOthercountiesOthercounties Japan,Korea,China,Australia,NewZealand,Japan,Korea,China,Australia,NewZealand,IndiaIndian nMorethan35countrieshaveGMOMorethan35countrieshaveGMOregulationsunderconsiderationregulationsunderconsiderationProposed FDA policy for v
29、oluntary labelingNot genetically modifiedX Virtually all commercial foods have been genetically modified.GMO freeX “Free”implies zero,which is difficult to verify.Proposed FDA policy for voluntary labelingGenetically engineeredThis product contains cornmeal that was produced using biotechnology.This
30、 product contains high oleic acid soybean oil from soybeans developed using biotechnology to decrease the amount of saturated fat.OKOKUnderlined part is mandatory,Rest is voluntary.Proposed FDA policy for voluntary labeling(cont.)We do not use ingredients produced using biotechnology.OKThis oil is m
31、ade from soybeans that were not genetically engineered.OKMain Pointsn nWhatisclimactericandnon-climactericfruit?Whatisclimactericandnon-climactericfruit?n nWhatisthebiosynthesispathwayofethyleneinWhatisthebiosynthesispathwayofethyleneinplant?plant?n nListthemethodstoreducespoilageinfruitsandListthemethodstoreducespoilageinfruitsandvegetables.vegetables.n nWhatsyourattitudetotransgenicfoods?Whatsyourattitudetotransgenicfoods?The End