Transcriptome sequencing reveals potential key genes of cellular changes during the first rapid growth stage of jujube fruit size

Cell number and size are essential factors in determining the final size of the fruit. However, studies on the cellular changes and molecular mechanisms of jujube fruit size development are still unclear. In this study, changes in fruit length, width, weight, and corresponding mesocarp cells were measured during jujube fruit development. The results showed that cell division and cell expansion jointly participated in the first rapid growth stage of fruit size, and cell expansion was the main factor in the second rapid growth stage of fruit size. In a further study, transcriptome sequencing was used to analyse the expression profile of fruit size's first rapid growth stage. Most of these DEGs were assigned to seven significant trends. Three genes related to the auxin signal transduction pathway and three genes related to the brassinosteroid biosynthesis signal transduction pathway were detected to be directly related to cell enlargement and cell division, respectively, which may regulate the first rapid growth of fruit size. In conclusion, candidate genes were provided for regulating fruit size in this study, which is beneficial for analysing the molecular mechanism of fruit size and lays a foundation for breeding large-fruit jujube cultivars.

细胞数目与大小是决定果实最终大小的关键因素。然而，目前针对枣果发育过程中的细胞变化及果实大小调控的分子机制，相关研究尚未明确。本研究测定了枣果发育阶段中果实长度、宽度、单果重及其对应中果皮细胞的动态变化。结果表明，细胞分裂与细胞扩张共同参与了果实大小的第一次快速生长阶段，而细胞扩张则是果实大小第二次快速生长阶段的主导因素。后续研究中，本研究通过转录组测序分析了果实大小第一次快速生长阶段的基因表达谱，大部分差异表达基因（Differentially Expressed Genes，DEGs）被归类为7个显著表达趋势。研究检测到3个与生长素信号转导通路相关的基因，以及3个与油菜素内酯生物合成信号转导通路相关的基因，它们分别与细胞增大和细胞分裂直接相关，可能调控果实大小的第一次快速生长过程。综上，本研究为果实大小调控提供了候选基因，有助于解析果实大小形成的分子机制，同时为培育大果型枣品种奠定了研究基础。