• In most legumes, two typical features found in leaves are diverse compound forms and the pulvinus‐driven nyctinastic movement. Many genes have been identified for leaf‐shape determination, but the underlying nature of leaf movement as well as its association with the compound form remains largely unknown.
• Using forward‐genetic screening and whole‐genome resequencing, we found that two allelic mutants of Medicago truncatula with unclosed leaflets at night were impaired in MtDWARF4A (MtDWF4A), a gene encoding a cytochrome P450 protein orthologous to Arabidopsis DWARF4.
• The mtdwf4a mutant also had a mild brassinosteroid (BR)‐deficient phenotype bearing pulvini without significant deficiency in organ identity. Both mtdwf4a and dwf4 could be fully rescued by MtDWF4A, and mtdwf4a could close their leaflets at night after the application of exogenous 24‐epi‐BL. Surgical experiments and genetic analysis of double mutants revealed that the failure to exhibit leaf movement in mtdwf4a is a consequence of the physical obstruction of the overlapping leaflet laminae, suggesting a proper geometry of leaflets is important for their movement in M. truncatula.
• These observations provide a novel insight into the nyctinastic movement of compound leaves, shedding light on the importance of open space for organ movements in plants.

中文翻译：

---

复合叶的几何形状在mtdwarf4a调节的紫花苜蓿叶片运动中起重要作用

• 在大多数豆科植物中，叶片中发现的两个典型特征是多种复合形式和由果皮驱动的夜色性运动。已经确定了许多用于确定叶形的基因，但是，叶运动的潜在本质以及其与复合形式的关联仍然未知。
• 使用正向基因筛选和全基因组重测序，我们发现MtDWARF4A（MtDWF4A）损害了两个截叶苜蓿的夜蛾等位基因突变体，该基因编码与拟南芥DWARF4同源的细胞色素P450蛋白。
• 所述mtdwf4a还突变体有轻微的油菜素类固醇（BR）缺陷表型轴承pulvini而不器官身份显著缺乏。无论mtdwf4a和DWF4可以进行全面的抢救MtDWF4A和mtdwf4a可以外源性24-EPI-BL的申请后，在晚上关闭他们的传单。手术实验和双突变体的遗传分析表明，未能表现出叶的运动mtdwf4a是重叠的单张薄片的物理障碍的结果，表明小叶的正确的几何形状是他们在运动中的重要蒺藜苜蓿。
• 这些观察结果为复合叶的夜生运动提供了新颖的见解，从而阐明了开放空间对于植物器官运动的重要性。