Sonn. is an important economic fruit tree in tropical and subtropical regions. Regrettably, the efficiency of plant regeneration via somatic embryogenesis in litchi is typically low due to the poor conversion of embryos to plants. The purpose of this study was to establish a regeneration system via somatic embryogenesis from immature embryos explants in ‘Heiye’ cultivar of litchi. Our results demonstrated that MS medium supplemented with 2.0mg L 2,4-D was optimal for callus induction. For somatic embryo (SE) induction, MS medium containing 0.5 g L activated charcoal (AC) was the most effective, while the use of zeatin (ZT) and thidiazuron (TDZ) resulted in abnormal somatic embryos. The rooting and regeneration rate of 2.15% and 17.5%, respectively, were achieved using MS medium supplemented with 0.5 g L AC. Furthermore, transcriptome analysis was performed on embryogenic callus (EC), globular embryo (GE), and heart embryo (HE) to explore the molecular mechanisms of early somatic embryogenesis. 2,587 common DEGs between EC_vs_GE and EC_vs_HE were identified, and the expression patterns of these common DEGs were separated into twelve major clusters. GO annotation and KEGG pathway analysis revealed that these common DEGs were implicated in plant hormone signal transduction, auxin-activated signaling pathway, and other biological processes. Additionally, differentially expression transcription factors were identified, and the function of which is specifically highly expressed during early somatic embryogenesis was verified. Overexpression of in tomato promotes callus and shoot formation. Therefore, this study can provide a theoretical basis and technical support for genetic breeding improvement of litchi.

中文翻译：

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荔枝体细胞胚胎发生再生体系的建立及早期体细胞胚胎发生转录组分析

桑恩。是热带、亚热带地区重要的经济果树。遗憾的是，由于胚胎向植物的转化较差，荔枝通过体细胞胚胎发生的植物再生效率通常较低。本研究的目的是通过“黑叶”荔枝品种未成熟胚外植体的体细胞胚胎发生建立再生系统。我们的结果表明，添加 2.0mg L 2,4-D 的 MS 培养基最适合愈伤组织诱导。对于体细胞胚 (SE) 诱导，含有 0.5 g/L 活性炭 (AC) 的 MS 培养基最有效，而使用玉米素 (ZT) 和噻苯隆 (TDZ) 会导致体细胞胚异常。使用添加0.5 g L AC的MS培养基，生根率和再生率分别为2.15%和17.5%。此外，对胚胎发生愈伤组织（EC）、球状胚胎（GE）和心脏胚胎（HE）进行转录组分析，以探索早期体细胞胚胎发生的分子机制。鉴定了 EC_vs_GE 和 EC_vs_HE 之间的 2,587 个共同 DEG，并将这些共同 DEG 的表达模式分为 12 个主要簇。 GO注释和KEGG通路分析表明，这些常见的DEGs参与植物激素信号转导、生长素激活信号通路和其他生物过程。此外，还鉴定了差异表达的转录因子，并验证了其在早期体细胞胚胎发生过程中特异性高表达的功能。在番茄中的过度表达促进愈伤组织和芽的形成。因此，本研究可为荔枝遗传育种改良提供理论依据和技术支持。