【摘要】 柑橘(Citrus)果实富含柠檬酸等营养成分。为了探究柑橘果实汁胞细胞中关键基因的转录变化对柠檬酸等品质相关代谢物积累的影响，分别对两个遗传相近的枸橼类柑橘品种’甜柠檬’(C. limetta)与’尤力克’(C. limon)进行果实品质分析。转录组测序结果对比分析表明，两个品种的果实汁胞细胞之间参与柠檬酸等代谢物的合成、分解、转运相关基因发生转录变化。在果汁可滴定酸含量差异显著的两个柑橘品种之间发现了4 044个差异表达基因。对差异表达基因进行了KEGG代谢通路的富集分析。低酸型’甜柠檬’的汁胞细胞中上调的差异表达基因富集于γ-氨基丁酸代谢(GABA shunt)等24个代谢通路；高酸型’尤力克’上调的差异表达基因富集于柠檬酸循环等13个代谢通路。在果实成熟期，两个品种之间的柠檬酸合成酶基因的相对表达量没有显著性差异；’尤力克’汁胞细胞中质子泵转运基因的相对表达量显著高于’甜柠檬’，从而促进’尤力克’汁胞细胞中液泡的酸化。果实有机酸含量可能与柠檬酸分解、质子泵转运相关基因的上调表达有关。本研究为深入解析柑橘属果实的有机酸代谢机理提供了一定理论依据。更多还原

【Abstract】 Fruit flesh of Citrus is rich in citrate and other nutrients. To better understand the effects of differential expression of genes(DEGs) on citrate and other important metabolites in Citrus, both fruit qualities and RNA-seq analysis were performed between ’Sweet lemon’ and ’Eureka’, respectively. The comparative analysis between 2 cultivars had been implemented using transcriptomics technology to identify the DEGs,which caused citrate accumulating in pulp. After transcriptomic sequencing for each fruit in 3 replicates, 73678 unigenes had been obtained, out of which the total 4 044 unigenes were differentially expressed between 2 cultivars. Subsequently, DEGs were further enriched into different pathways by KEGG. The upregulating DGEs in ’Sweet lemon’ with lower citrate contents were enriched into 24 pathways, including GABA shunt.Besides, upregulating DEGs in ’Eureka’ with higher citrate contents were enriched into 13 pathways, including citrate cycle. At fruit ripening stage, the significantly differential expression of citrate synthase was not found between 2 cultivars. In addition, proton pump gene in ’Eureka’ had higher transcription levels than ’Sweet lemon’ at fruit ripening stage, so that it was benefit for vacuole acidification in fruit. It could be concluded that up-regulating expression of genes involved into citrate metabolism and proton transporting were correlated with organic acidity accumulations in Citrus fruits. This study provides an insight into organic acids metabolism in Citrus and is useful for breeding program in future.更多还原