Genetic mechanism of leaf blade flattening in unifacial leaves

被子植物的叶通常发育为两面结构，具有明显的近轴和远轴特性。然而，一些单子叶植物物种，如鸢尾和韭菜，发展单面叶，其中叶片只有远轴身份。在双面叶中，叶片变平需要近轴-远轴极性，而许多单面叶尽管叶片被远轴化，但仍变平。在这里，我调查了单面叶中扁平叶片的发育和进化的机制。我证明了垂叶（DL）基因的直系同源物可以促进单面叶片的扁平化。在此基础上，提出了单叶叶片扁平化的遗传模型。

Angiosperm leaves generally develop as bifacial structures with distinct adaxial and abaxial identities. However, several monocot species, such as iris and leek, develop unifacial leaves, in which leaf blades have only abaxial identity. In bifacial leaves, adaxial-abaxial polarity is required for leaf blade flattening, whereas many unifacial leaves become flattened despite their leaf blades being abaxialized. Here, I investigated the mechanisms underlying the development and evolution of flattened leaf blades in unifacial leaves. I demonstrated that an ortholog of the DROOPING LEAF (DL) gene may promote flattening of the unifacial leaf blade. Based on the results, I proposed genetic model for the leaf blade flattening in unifacial leaves.