Summary Passion flower extrafloral nectaries (EFNs) protrude from leaves and facilitate mutualistic interactions with insects; however, how age cues control EFN growth remains poorly understood. Here, we examined leaf and EFN morphology and development of two Passiflora species with distinct leaf shapes, and compared the phenotype of these to transgenics with manipulated activity of the age‐dependent miR156, which targets several SQUAMOSA PROMOTER‐BINDING PROTEIN‐LIKE (SPL) transcription factors. Low levels of miR156 correlated with leaf maturation and EFN formation in Passiflora edulis and P. cincinnata. Accordingly, manipulating miR156 activity affected leaf heteroblasty and EFN development. miR156‐overexpressing leaves exhibited less abundant and tiny EFNs in both Passiflora species. EFN abundance remained mostly unchanged when miR156 activity was reduced, but it led to larger EFNs in P. cincinnata. Transcriptome analysis of young leaf primordia revealed that miR156‐targeted SPLs may be required to properly express leaf and EFN‐associated genes. Importantly, altered miR156 activity impacted sugar profiles of the nectar and modified ecological relationships between EFNs and ants. Our work provides evidence that the miR156/SPL module indirectly regulates EFN development in an age‐dependent manner and that the EFN development program is closely associated with the heteroblastic developmental program of the EFN‐bearing leaves.

中文翻译：

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西番莲属的叶片异质成层和花外蜜腺发育需要年龄依赖性 miR156 的适当活性。


摘要 西番莲花外蜜腺 （EFN） 从叶子中伸出，促进与昆虫的共生互动;然而，年龄线索如何控制 EFN 生长仍然知之甚少。在这里，我们检查了两种具有不同叶形的西番莲物种的叶片和 EFN 形态和发育，并将这些物种的表型与具有年龄依赖性 miR156 操纵活性的转基因进行了比较，该基因靶向几种鳞状启动子结合蛋白样 （SPL） 转录因子。低水平 miR156 与西番莲和辛辛那塔的叶片成熟和 EFN 形成相关。因此，操纵 miR156 活性影响叶片异质成层和 EFN 发育。miR156 过表达的叶子在两种西番莲物种中都表现出较少丰富和微小的 EFN。当 miR156 活性降低时，EFN 丰度基本保持不变，但它导致辛辛那塔 P. 的 EFN 更大。幼叶原基的转录组分析显示，正确表达叶和 EFN 相关基因可能需要 miR156 靶向的 SPL。重要的是，改变的 miR156 活性影响了花蜜的糖分谱，并改变了 EFN 与蚂蚁之间的生态关系。我们的工作提供了证据表明，miR156/SPL 模块以年龄依赖性方式间接调节 EFN 发育，并且 EFN 发育程序与携带 EFN 的叶片的异母细胞发育程序密切相关。