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外源腐胺缓解黄瓜幼苗盐胁迫伤害的光合作用机理.docx

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外源腐胺缓解黄瓜幼苗盐胁迫伤害的光合作用机理 Introduction Saltstressisacommonprobleminagriculturalpractices,particularlyinaridandsemi-aridregions,whichlimitscropproductivityandquality.Excesssaltcontentinthesoilresultsinosmoticstressandionictoxicity,leadingtostomataclosure,damagetothephotosyntheticapparatus,andadecreaseinchlorophyllsynthesisandphotosyntheticrate.Therefore,theidentificationofeffectivemethodstomitigatetheadverseeffectsofsaltstressonplantsiscrucial.Inthisstudy,weexaminetheroleofexogenouspolyaminesinalleviatingsalt-induceddamagetophotosynthesisincucumberseedlings. Mechanismsofsalt-induceddamagetophotosynthesisincucumberseedlings Photosynthesisisessentialforplantgrowthanddevelopment,anditisparticularlyvulnerabletosaltstress.Underhighsalinity,thewaterpotentialofthesoildecreases,whichleadstoadecreaseinwateruptakebytherootsanddecreasesturgorpressureintheguardcellssurroundingthestomata.Asaresult,stomatalconductanceandtherateofCO2diffusionintotheleavesdecrease,leadingtoadeclineinphotosyntheticrate.Furthermore,highsalinitycandirectlydamagethephotosystemII(PSII)reactioncenterandtheantennacomplex,resultinginadecreaseintheefficiencyoflightenergyconversionandelectrontransport,leadingtoreducedphotosynthesis. Polyaminesandtheirroleincellularhomeostasis Polyaminesarelowmolecularweightorganicaminesthatareubiquitousinlivingorganisms,andtheyareessentialforcellgrowthanddifferentiation.Theyareinvolvedinseveralphysiologicalprocesses,includingDNAandRNAsynthesis,proteinsynthesis,iontransport,andregulationofthecellcycle.Inplants,polyaminesaresynthesizedfromornithineorarginineandareinvolvedinvariousdevelopmentalprocesses,includingseedgermination,plantgrowth,andresponsetoabioticstress.Themostcommonpolyaminesinplantsareputrescine(Put),spermidine(Spd),andspermine(Spm).Studieshaveshownthatexogenousapplicationofpolyaminescanamelioratethenegativeeffectsofsaltstressonplantgrowthanddevelopment. Polyaminesimprovechlorophyllsynthesisandphotosyntheticrateincucumberseedlingsundersaltstress Toinvestigatetheeffec