脐橙晚熟突变体及其野生型果实柠檬酸代谢基因表达分析

Expression Analysis of Citrate Metabolic Related Genes in Late-ripening Mutant of Navel Orange and Its Wild Type

‘奉节晚橙’(Citrus sinensis L.Osbeck)是来源于‘奉节72-1’脐橙的晚熟芽变。采用qRT-PCR方法测定了‘奉节72-1’与其晚熟突变体果实4个发育时期柠檬酸代谢相关基因的表达。结果表明,糖酵解途径中‘奉节72-1’脐橙基因的表达高于‘奉节晚橙’;但是柠檬酸合成相关基因CsCS4、CsPEPC1、CsPEPC2、CsPEPC4、CsME1、CsME4的表达水平低于‘奉节晚橙’。果实发育后期,‘奉节72-1’脐橙中CsACO1、CsGAD4、CsGS1等柠檬酸降解相关基因表达水平逐渐升高,且表达量高于‘奉节晚橙’。两者间柠檬酸含量的差异是代谢途径中多种基因共同作用的结果。通过相关性分析,推断CsME1、CsME4可能是影响柠檬酸含量差异的关键基因。

‘Fengwan＇orange（Citrus sinensis L. Osbeck）is the spontaneous late-ripening mutant of ‘Fengjie 72-1＇. The expression of citrate metabolic related genes during fruit four developmental stages of Fengwan and its wild type Fengjie 72-1 orange was analyzed by qRT-PCR and the results revealed that key genes of glycolysis metabolism in Fengjie 72-1 expressed higher than that in Fengwan. However,citrate biosynthesis genes,such as CsCS4,CsPEPC1,CsPEPC2,CsPEPC4,CsME1 and CsME4 expressed lower than that in Fengwan. Moreover,transcript levels of genes,such as CsACO1,CsGAD4 and CsGS1 involved in citrate degradation pathways were increased gradually during fruit late development,and the expression levels in Fengjie 72-1 were higer than that in Fengwan orange. Genes involved in synthesis and degradation metabolic pathways coordinately contribute to the different content of citric acid. Correlation analysis revealed that CsME1 and CsME4 may be key genes affecting the different content of citric acid between Fengwan orange and its wild type.