College of Forestry, Northwest Agriculture and Forestry University, Yangling 712100, Shaanxi, China.
Key Comprehensive Laboratory of Forestry of Shaanxi Province, Northwest Agriculture and Forestry University, Yangling 712100, Shaanxi, China.
Tree Physiol. 2023 Jan 5;43(1):142-153. doi: 10.1093/treephys/tpac098.
Hybridization is an important approach to the production of new varieties with exceptional traits. Although the kernel rate of wild jujube (Ziziphus jujuba Mill. var. spinosa Hu.) is generally high, that of cultivated jujube (Z. jujuba Mill.) is low, greatly hampering the jujube breeding process. However, the mechanism by which this trait changed during jujube domestication remains unclear. Here, we explored the potential regulatory network that governs jujube embryo abortion using correlation analysis of population traits, artificial pollination, sugar content measurements and multi-omics analysis. The results showed that embryo abortion was an important reason for the low kernel rate of cultivated jujube, and kernel rate was negatively correlated with edible rate. Twenty-one days after pollination was a critical period for embryo abortion. At this time, the sugar content of cultivated 'Junzao' kernels decreased significantly compared with that of the pulp, but sugar content remained relatively stable in kernels of wild 'Suanzao'. A total of 1142 differentially expressed genes targeted by 93 microRNAs (miRNAs) were identified by transcriptome, miRNA and degradome sequencing, and may be involved in the regulation of embryo abortion during kernel development. Among them, DELLA protein, TCP14 and bHLH93 transcription factors have been shown to participate in the regulation of embryonic development. Our findings suggest that carbohydrate flow between different tissues of cultivated jujube exhibits a bias toward the pulp at 21 days after pollination, thereby restricting the process of kernel development. This information enhances our understanding of the embryo abortion process and reveals miRNA-target gene pairs that may be useful for molecular-assisted breeding.
杂交是培育具有特殊性状的新品种的重要方法。虽然野生酸枣（Ziziphus jujuba Mill. var. spinosa Hu.）的核率一般较高，但栽培酸枣（Z. jujuba Mill.）的核率较低，极大地阻碍了枣树的育种进程。然而，这种性状在枣树驯化过程中发生变化的机制尚不清楚。在这里，我们使用群体性状相关性分析、人工授粉、糖含量测定和多组学分析，探索了控制枣胚败育的潜在调控网络。结果表明，胚败育是栽培枣核率低的重要原因，核率与可食率呈负相关。授粉后 21 天是胚败育的关键时期。此时，栽培“骏枣”核仁的糖含量与果肉相比显著下降，但野生“酸枣”核仁中的糖含量相对稳定。通过转录组、miRNA 和降解组测序，共鉴定出 1142 个靶向 93 个 microRNAs (miRNAs) 的差异表达基因，可能参与了核仁发育过程中胚败育的调控。其中，DELLA 蛋白、TCP14 和 bHLH93 转录因子已被证明参与了胚胎发育的调控。我们的研究结果表明，授粉后 21 天，栽培酸枣不同组织之间的碳水化合物流偏向果肉，从而限制了核仁的发育过程。这些信息增强了我们对胚败育过程的理解，并揭示了可能对分子辅助育种有用的 miRNA-靶基因对。
