DEAD-box (DDX) proteins belong to the largest subfamily of RNA helicase SF2, which contributes to all biological processes of RNA metabolism in the plant kingdom. Till now, no significant data are available regarding studies on DDX in Somatic Embryogenesis (SE) of woody plants. It is important to investigate the biological function of the DlDDX family in longan SE. Thus, a comprehensive analysis of 58 longan DEAD-box (DlDDX) genes characterization was performed by genome-wide identification and transcript abundance validation analysis. Homologous evolution has revealed that some DlDDXs in longan had high sequence similarity with Mus musculus, Citrus and Saccharomyces cerevisiae, indicating that DlDDXs were highly conservative in the animal, plant, and microorganism. Remarkably, gene duplication, purifying selection, and alternative splicing events, and new auxiliary domains have likely contributed to the functional evolution of DlDDX, indicating that DlDDX appeared neofunctionalization in longan. Besides, DlDDX3, 15, 28, 36 might interact with protein complex (MAC3A, MAC3B, CDC5, CBP20) of miRNA biosynthesis. Notably, DlDDX28 contained a novel auxiliary domain (CAF-1 p150), which might contribute to DNA demethylation in longan early SE. 4 DlDDX genes significantly expressed not only in early SE and zygotic embryogenesis (ZE) but also up-regulated at high levels in 'Honghezi' and 'Quanlongbaihe' with abortive seeds, which are of great significance. Moreover, some DlDDXs presented abiotic stress-response dynamic expression patterns by ABA, SA, JA, and NaCl treatments during early SE. Hence, DEAD-box is essential to SE development and seed abortive in longan.

中文翻译：

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龙眼龙眼早期体细胞胚胎发生相关的DEAD-box解旋酶家族的全基因组鉴定和表征

DEAD-box (DDX) 蛋白属于 RNA 解旋酶 SF2 的最大亚家族，它有助于植物界 RNA 代谢的所有生物过程。到目前为止，还没有关于 DDX 在木本植物体细胞胚胎发生 (SE) 中的研究的重要数据。研究龙眼 SE 中 DlDDX 家族的生物学功能非常重要。因此，通过全基因组鉴定和转录本丰度验证分析对 58 个龙眼死盒 (DlDDX) 基因特征进行了综合分析。同源进化表明，龙眼中的一些DlDDXs与Mus musculus、Citrus和Saccharomyces cerevisiae具有高度的序列相似性，表明DlDDXs在动物、植物和微生物中具有高度的保守性。值得注意的是，基因复制、纯化选择和选择性剪接事件，新的辅助域可能对 DlDDX 的功能进化做出了贡献，表明 DlDDX 在龙眼中出现了新功能化。此外，DlDDX3、15、28、36可能与miRNA生物合成的蛋白质复合物（MAC3A、MAC3B、CDC5、CBP20）相互作用。值得注意的是，DlDDX28 包含一个新的辅助结构域（CAF-1 p150），这可能有助于龙眼早期 SE 中的 DNA 去甲基化。4 DlDDX基因不仅在早期SE和合子胚胎发生（ZE）中显着表达，而且在'红河子'和'全龙白河'有败育种子中高水平上调，具有重要意义。此外，一些 DlDDX 在早期 SE 期间通过 ABA、SA、JA 和 NaCl 处理呈现非生物胁迫反应动态表达模式。因此，DEAD-box 对龙眼的 SE 发育和种子流产至关重要。