Crape myrtle is an important summer flowering shrub with abundant flowers and long flowering period, and widely used in gardens around the world. Though the MADS-box genes have profound impacts on floral organogenesis in other plants, their function and expression patterns in Lagerstroemia remain unclear. In the study, we conducted the comprehensive analysis of the MADS-box family from three Lagerstroemia species, including 94 genes in L. suprareticulata, 83 genes in L. speciosa and 79 genes in L. indica. The MADS-box genes were classified into Type I (104 genes) and Type II (152 genes). The difference in gene numbers observed among the three species was closely related to tandem and segmental duplication. Homologous gene pairs were prevalent among Lagerstroemia species, offering a profound understanding of the evolutionary dynamics of MADS-box gene family. The promoter regions of type II genes are mostly composed of light-responsive and hormone-inducible elements. Expression profiles of ABCDE-class genes showed differences in the four-whorl flower organ. Yeast two-hybrid assay and luciferase complementation assay indicated that LiMADS53 and LiMADS60 synergistically regulated sepal initiation while LiMADS49 and LiMADS42 exhibited expression in petals and stamens. LiMADS42 and LiMADS53 contributed to stamen development. These results provide a basis for mining the genes that determine flower organs of crape myrtle, and lay a solid foundation for improving flower type and breeding of new cultivars.

中文翻译：

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MADS-box 基因的全基因组分析揭示了它们在 Lagerstroemia 花器官发育中的作用


紫薇是重要的夏季开花灌木，花期丰富，花期长，在世界各地的花园中得到广泛应用。尽管 MADS-box 基因对其他植物的花器官发生有深远影响，但它们在 Lagerstroemia 中的功能和表达模式仍不清楚。在这项研究中，我们对 3 个 Lagerstroemia 物种的 MADS-box 家族进行了综合分析，包括 L. suprareticulata 的 94 个基因、L. speciosa 的 83 个基因和 L. indica 的 79 个基因。MADS-box 基因分为 I 型 （104 个基因） 和 II 型 （152 个基因）。在 3 个物种之间观察到的基因数差异与串联和节段重复密切相关。同源基因对在 Lagerstroemia 物种中普遍存在，为了解 MADS-box 基因家族的进化动力学提供了深刻的理解。II 型基因的启动子区主要由光响应和激素诱导元件组成。ABCDE 类基因的表达谱显示四轮花器官存在差异。酵母双杂交试验和荧光素酶互补试验表明，LiMADS53 和 LiMADS60 协同调节萼片起始，而 LiMADS49 和 LiMADS42 在花瓣和雄蕊中表达。LiMADS42 和 LiMADS53 有助于雄蕊发育。这些结果为挖掘决定紫薇花器官的基因提供了基础，为改良花型和培育新品种奠定了坚实的基础。