外源甜菜碱提高黄瓜幼苗抗冷性研究

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1、华南师范大学硕士学位论文外源甜菜碱提高黄瓜幼苗抗冷性研究姓名：李芸瑛申请学位级别：硕士专业：植物学指导教师：叶庆生;梁广坚2003.6.1GBHPLCSODPODCATMDAFWMindhUO．D．缩写词glycinebetaineHighperformanceliquidchromatographSuperoxidedismutasePeroxidaseCatalaseMalondialdehydeFreshweightminutedayhourUnitOpticalDensity甘氨酸甜菜碱高效液相色谱超氧物岐化酶过氧化物酶过氧化氢酶丙二醛鲜重分钟天小时酶

2、单位光密度摘要本文以黄瓜幼苗为材料，探讨了外源GB的处理方法及浓度对幼苗抗冷性的影响，使用HPLC法测定了幼苗体内GB的含量，并对外源GB提高幼苗抗冷的机理进行了探讨。主要结果如下：外源GB有明显提高黄瓜幼苗抗冷作用。根喂GB处理以5．0mmol／L的效果最佳，恢复生长后，幼苗的成活率、叶绿素含量及光合速率比对照均明显增加；叶喷GB处理以25．0mmol／L的效果最佳，然而，叶面喷施浓度过高(50．0mmol／L)对幼苗有一定的毒害作用。黄瓜幼苗在室温或低温胁迫(6±1℃)下不积累GB，幼苗易吸收外源GB并能积累到一定水平，在0～25．0mmol／L的浓度范围

3、内，随着浓度升高，幼叶内GB含量越高。低温胁迫下，外源GB处理幼苗可缓解叶绿素含量的下降及质膜相对透性的增加，抑制MDA、脯氨酸的积累及减缓了SOD、CAT活性的下降，并增强了POD活性。结果表明，外源GB可能通过防止膜脂过氧化，保护了膜的完整性和稳定性，从而提高了黄瓜幼苗的抗冷性。关键词：GB√黄瓜窈备抗溶衫光合癣SODPODCAT关键词：黄瓜幼苗抗冷性光合速率X《，AbstractInthispaper,wehadresearchedtheeffectofGBonthecoldresistanceofcucumberseedlingsanditsmecha

4、nism．Furthermore，thechangesofGBcontentinseedlingsduringthecoldtreatmentweremeasuredbyHPLC．ExogenousGBcouldobviouslyimprovecoldresistanceofseedlings．ItisshownthatwhenseedlingswastreatedbydifferentconcentrationofGBthroughtheroot—absorbing，thesurvivalrate，chlorophyllcontentandphotosynt

5、heticrateofseedlingswereobviouslyhigherthanthoseofcontrol，GBconcentrationof5．0mmol／Lwasthebestforpromotingcold-resistanceoftheseedlings．Moreover,whentheseedlingsweretreatedbysprayingleaveswithGB，thecold—resistanceofseedlingswasalsoincreased，inwhich，GB25．0mmol／Lwasthebestconcentratio

6、n，butathighconcentrationofGB，50．Ommol／Lwouldbetoxictoseedlings．CucumberseedlingswereunabletosynthesizedetectableamountofGBundercoldstress(6+1℃)orroomtemperature(20～26V)，andtheycouldeasilyabsorbexogenousGB．TheamountofGBabsorbedbytheseedlingsincreasedwithconcentrmionofGBconcentrations

7、intherangeof0-25．0mmol／L．Undercoldstress，exogenousGBcouldreduceslowlythecontentofchlorophyllandincreaseofrelativepermeabilityofmembrane，reducetheaccumulationofMDAandproline，inhibitthereductionofSODandCATactivitiesandincreasethePODactivityTheresuItsaboveshowedthatexogenousGBmaypreven

8、tlipidDeroxidatiOno