Somatic embryogenesis is an effective tool for the production of forest tree seedlings with desirable characteristics; however, the low initiation frequency and productivity of high-quality mature somatic embryos are still limiting factors for Larix kaempferi (Japanese larch). Here, we analyzed the expression pattern of L. kaempferi cyclin-dependent kinase B 1;2 (LaCDKB1;2) during somatic embryogenesis in L. kaempferi and its relationship with the cell proliferation rate. We also analyzed the effect of LaCDKB1;2 over-expression on somatic embryo quality. The results revealed a positive correlation between LaCDKB1;2 expression and the cell proliferation rate during the proliferation stage. After LaCDKB1;2 over-expression, the proliferation rate of cultures increased, and the number of somatic embryos in transgenic cultures was 2.69 times that in non-transformed cultures. Notably, the number of normal cotyledonary embryos in transgenic cultures was 3 times that in non-transformed cultures, indicating that LaCDKB1;2 not only increases the proliferation of cultures and the number of somatic embryos but also improves the quality of somatic embryos. These results provide insight into the regulatory mechanisms of somatic embryogenesis as well as new Larix breeding material.

中文翻译：

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细胞周期基因 LaCDKB1;2 的过表达促进落叶松体细胞胚胎发生过程中细胞增殖和正常子叶胚胎的形成

体细胞胚胎发生是生产具有理想特性的林木幼苗的有效工具；然而，高质量成熟体细胞胚胎的低启动频率和生产力仍然是Larix kaempferi（日本落叶松）的限制因素。在这里，我们分析了L的表达模式。 L. kaempferi体细胞胚胎发生过程中的山柰细胞周期蛋白依赖性激酶 B 1;2 (LaCDKB1;2)及其与细胞增殖率的关系。我们还分析了LaCDKB1;2过表达对体细胞胚胎质量的影响。结果显示LaCDKB1;2之间呈正相关增殖期的表达和细胞增殖率。LaCDKB1 ;2过表达后，培养物的增殖率增加，转基因培养物的体细胞胚胎数是未转化培养物的2.69倍。值得注意的是，转基因培养物中正常子叶胚的数量是非转化培养物中的3倍，表明LaCDKB1;2不仅增加了培养物的增殖和体细胞胚胎的数量，而且提高了体细胞胚胎的质量。这些结果提供了对体细胞胚胎发生的调控机制以及新落叶松育种材料的深入了解。