黄瓜黄绿叶突变体光合色素变化及相关基因差异表达

Changes of the Photosynthetic Pigment and Differential Expression of the Correlated Genes in a Chlorophyll-Deficient Cucumber Mutant (Cucumis sativus L.)

【目的】黄瓜黄绿叶突变体是进行光合系统研究和遗传育种研究的重要材料,明确其叶色突变机理,可为进一步利用该性状进行基因定位、基因克隆等研究提供理论依据。【方法】本试验对黄瓜黄绿叶突变体9110Gt叶色黄化和转绿后的光合色素成分、含量和原叶绿素含量进行测定,并利用cDNA-AFLP技术及cDNA-Ad-SRAP技术,进行相关基因差异表达研究,获得差异表达片段。【结果】突变体9110Gt和野生型9110G在叶色素组分上没有显著差异,但突变体的光合色素及原叶绿素含量都低于正常株。从该突变材料中分离到的9条与叶色突变基因相关的差异表达片段与叶绿体和线粒体中基因具有较高同源性。【结论】该突变体叶色黄化是由于原叶绿素合成受阻从而导致叶绿素a合成减少,进而导致叶绿素含量降低,叶片光合色素比例发生变化,叶色发生变异。基因转录水平的研究进一步说明引起该现象的原因可能是与叶绿体发育、叶绿素生物合成相关的基因发生了突变。

Objective Cucumber chlorophyll-deficient mutant is an ideal material for studies on the photosynthetic system and genetic breeding.To make clear on the mechanism of the leaf colour transformation in yellow leaf mutant will provide a theoretical basis for quantitative trait loci gene mapping and gene cloning.Method A cucumber chlorophyll-deficient mutant named 9110Gt and its wild type named 9110G were used as materials in this study.The photosynthetic pigment components,contents and Pchl contents in 9110Gt and 9110G were analysed.cDNA-AFLP and cDNA-Ad-SRAP were employed to detect the differentially expressed genes.Result Spectral analysis showed that there was no significant difference in the pigment components between 9110Gt and 9110G,but the contents of photosynthetic pigment and protochlorophyll in 9110Gt were lower than in wild type in yellow period.Nine candidate transcript derived fragments（TDFs） were obtained.The candidate transcript derived fragments had highly identities with cucumber mitochondrial and chloroplast genome sequence.Conclusion It was concluded that there was a blockage in the protochlorophyllide biosynthesis,then leading to lower chlorophyll content and make changes in the proportion of photosynthetic pigment of mutant.The leaf colour mutant was may be due to gene mutations in chloroplast development and chlorophyll biosynthesis.