一个新的薄皮甜瓜叶色突变体的生理特性及超微结构分析

摘要

[目的]研究薄皮甜瓜自然黄化转绿突变体(MT)与非突变亲本(WT)在生长、生理特性、光合作用及叶绿体发育等方面的区别与变化.[方法]对MT、WT及组配子代F(1MT×WT),rF(1WT×MT)的主要农艺性状、光合指标、光合色素含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性、丙二醛(MDA)含量、叶绿体超微结构进行测定和比较分析.[结果]与WT相比,MT植株长势较弱,生育期滞后,净光合速率无显著差异.通过杂交,F1、rF1可恢复正常生长;MT的叶片颜色随生长发育而转变,从黄色转为黄绿色,叶脉为绿色,叶片中叶绿素含量显著低于WT,在结果期MT叶片中叶绿素及类胡萝卜素含量较WT降低了25.69％、21.26％,但叶绿素a与叶绿素b的比值显著高于WT;自然黄化转绿突变体MT的SOD、POD、CAT酶活性以及MDA含量高于WT,在结果期,分别提高了65.45％、13.91％、3.23％、15.14％;透射电镜观察结果显示黄化转绿突变体MT的叶绿体中基粒片层堆叠不规律,间距大,排列疏松,双层膜结构不清晰,叶绿体结构发育异常,与WT差异明显.[结论]在全生育期中,虽然MT植株矮小,叶绿素含量均显著低于WT,叶绿体结构也有所差异,但光合速率却无显著差异,说明其光合机构功能基本完好;在结果期,MT叶片中抗氧化酶活性均显著高于WT,MDA含量在全生育期中均显著高于WT,说明MT抗氧化酶系统较WT反映更为活跃,但F1、rF1与WT差异不显著.%[Objective]The aim of the study was to study the differences in growth,physiological charac-teristics and chloroplast development between leaf color mutant(MT)and wild type(WT).[Method]Agro-nomic traits,photosynthetic parameters,photosynthetic pigment content,superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)activity and MDA content and chloroplast ultrastructure of MT,WT,F1(MT×WT)and rF1(WT×MT)were investigated.[Result]The weaker growth of MT yielded a delayed growth stage.There was no significant change in the photosynthetic rate.With hybridization F1,rF1 could go back to the normal growth.The leaf color of MT changed with the growth and developed from yellow to yellowish green but the veins were still green.The chlorophyll content of MT leaf was signifi-cantly lower than that of WT.The Chlorophyll and carotenoid content were reduced by 25.69％and 21.26％,respectively,during the fruiting stage.However,the ratio of chlorophyll a to chlorophyll b was sig-nificantly higher in the MT leaves than in WT leaves.SOD,POD and CAT enzyme activities and MDA content were higher in MT than in WT and them were increased by 65.45％,13.91％,3.23％,15.14％in the stage,respectively.The observation of transmission electron microscopy(TEM)showed that the stacking of grana was irregular in the chloroplast structure of MT leaf and the grana lamellae were deranged with a line shape,indicating differences in the chloroplast structures between MT and WT.[Conclusion]In the whole growth stage,the shorter height,lower chlorophyll content in WT than in MT and different chloroplast structure between them.There is no significant difference in photosynthetic rate,suggesting that a basically intact function of photosynthetic apparatus.The antioxidant enzyme activity and was significantly higher in the MT than in the WT during fruiting stage and the MDA content was also significantly in the MT higher than in the WT during the whole growth stage.However,no significant difference among F1,rF1,and WT was ovserved.