Horticulture Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China.
State-Sichuan Joint Engineering Laboratory of Citrus Breeding and Cultivation, Chengdu, 610066, China.
BMC Genomics. 2017 Dec 21;18(1):984. doi: 10.1186/s12864-017-4366-2.
Transcriptome and proteome analyses on fruit pulp from the blood orange 'Zaohong' and the navel orange 'twenty-first century' were performed to study Citrus sinensis quality-related molecular changes during consecutive developmental periods, including young fruit, fruit-coloring onset and fruit delayed-harvest for two months, during which fruit remained on the trees.
The time-course analysis for the fruit developmental periods indicated a complex, dynamic gene expression pattern, with the numbers of differentially expressed genes (DEGs) between the two cultivars being 119, 426 and 904 at the three continuous stages tested during fruit development and ripening. The continuous increase in total soluble solids over the course of fruit development was correlated with up-regulated sucrose phosphate synthase (SPS) transcription levels in both cultivars. Eleven differentially expressed genes between the two cultivars involved in the flavonoid pathway were significantly enriched at the onset of the fruit-coloring stage when anthocyanins were detected in blood orange alone. Among 5185 proteins, 65 up-regulated and 29 down-regulated proteins were co-expressed with their cognate mRNAs with significant transcription and protein expression levels when the fruits from the two cultivars were compared at the fruit delayed-harvest stage. Additionally, important genes participating in the γ-aminobutyric acid (GABA) shunt were activated in blood orange at two significant expression levels in the fruit delayed-harvest stage. Thus, organic acids in fruit continuously decreased during this stage.
This research was the first to provide a more comprehensive understanding of the differentially expressed genes involved in anthocyanin, sucrose and citrate metabolism at the transcriptome and proteome levels in C. sinensis, especially during the fruit delayed-harvest stage.
对血橙“早红”和脐橙“21 世纪”的果肉进行转录组和蛋白质组分析，以研究柑橘属果实连续发育期间与品质相关的分子变化，包括幼果、果实着色开始和果实延迟收获两个月，在此期间果实仍留在树上。
对果实发育时期的时间进程分析表明，存在复杂、动态的基因表达模式，两个品种在果实发育和成熟过程中的三个连续阶段的差异表达基因（DEGs）数量分别为 119、426 和 904。在果实发育过程中总可溶性固体的持续增加与两个品种中蔗糖磷酸合酶（SPS）转录水平的上调有关。在花色苷仅在血橙中检测到的着色阶段开始时，两个品种之间涉及类黄酮途径的 11 个差异表达基因显著富集。在 5185 种蛋白质中，当比较两个品种在果实延迟收获阶段时，有 65 个上调和 29 个下调的蛋白质与它们的同源 mRNA 共表达，转录和蛋白表达水平显著。此外，在果实延迟收获阶段，参与γ-氨基丁酸（GABA）分流的重要基因在血橙中被激活到两个显著表达水平。因此，在此阶段，果实中的有机酸不断减少。
本研究首次在柑橘属水平上，从转录组和蛋白质组水平上，更全面地了解了花色苷、蔗糖和柠檬酸代谢中差异表达基因的作用，特别是在果实延迟收获阶段。
