Strawberry is a typical nonclimacteric fruit, whose ripening mechanism needs to be further investigated. Sucrose has been recently proved as a signal molecule, participating in strawberry fruit ripening and related processes. While in the effects of sucrose application timing and concentration on ripening, fruit qualities remain unclear, as well as the transcriptome-wide details about the effects of sucrose on the gene expression involved in ripening-related processes. In this study, strawberry fruits at the degreening (DG), white (W), and initial-red (IR) stages were treated with different concentration of sucrose. The results showed that anthocyanin was increased while total polyphenol concentration (TPC) and total flavonoid concentration (TFC) were decreased during fruit development after sucrose treatment. Interestingly, It was showed that 100 mM sucrose application at the DG stage had the most obvious effects on fruit ripening; it made all the fruits turn into full-red (FR) around 4 days (d) earlier than the control, while it did not affect fruit quality traits and most bioactive compounds in the FR fruits. Subsequently, RNA sequencing (RNAseq) of the fruits collected at 8 days after 100 mM sucrose treatment was carried out. It was suggested that 993 genes were differentially expressed comparing with the control. Transcriptome-based expression analysis revealed that sucrose induced the expression of genes involved in the AsA and anthocyanin biosynthesis, while largely suppressed the expression of genes in TCA. The results obtained in this study provided more expression profiles of ripening-related genes under the treatment of sucrose, which will contribute to a better understanding for the mechanism underlying sucrose-induced fruit ripening.

中文翻译：

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蔗糖促进草莓果实的成熟并影响与成熟有关的过程。

草莓是一种典型的非更年期水果，其成熟机理有待进一步研究。蔗糖最近被证明是信号分子，参与草莓果实的成熟和相关过程。尽管蔗糖施用的时机和浓度对成熟有影响，但果实品质仍不清楚，转录范围的细节也涉及蔗糖对与成熟相关的过程中基因表达的影响。在这项研究中，用不同浓度的蔗糖处理了定级（DG），白（W）和初红（IR）阶段的草莓果实。结果表明，在蔗糖处理后的果实发育过程中，花色苷含量增加，而总多酚浓度（TPC）和总黄酮浓度（TFC）降低。有趣的是 结果表明，在DG期施用100 mM蔗糖对果实成熟有最明显的影响。它使所有果实都比对照早4天（d）变成全红色（FR），而它并没有影响FR果实中的果实品质性状和大多数生物活性化合物。随后，对100 mM蔗糖处理后第8天收集的果实进行RNA测序（RNAseq）。提示与对照相比993基因差异表达。基于转录组的表达分析表明，蔗糖诱导了AsA和花色苷生物合成中涉及的基因的表达，而在很大程度上抑制了TCA中的基因表达。这项研究获得的结果为蔗糖处理下的成熟相关基因提供了更多的表达特征，