Department of Biology, Maynooth University, Ireland.
The Max Plank Institute for Plant Breeding Research, Cologne, Germany.
PLoS Genet. 2023 Oct 11;19(10):e1011000. doi: 10.1371/journal.pgen.1011000. eCollection 2023 Oct.
In Arabidopsis thaliana, stomata are composed of two guard cells that control the aperture of a central pore to facilitate gas exchange between the plant and its environment, which is particularly important during photosynthesis. Although leaves are the primary photosynthetic organs of flowering plants, floral organs are also photosynthetically active. In the Brassicaceae, evidence suggests that silique photosynthesis is important for optimal seed oil content. A group of transcription factors containing MADS DNA binding domains is necessary and sufficient to confer floral organ identity. Elegant models, such as the ABCE model of flower development and the floral quartet model, have been instrumental in describing the molecular mechanisms by which these floral organ identity proteins govern flower development. However, we lack a complete understanding of how the floral organ identity genes interact with the underlying leaf development program. Here, we show that the MADS domain transcription factor AGAMOUS (AG) represses stomatal development on the gynoecial valves, so that maturation of stomatal complexes coincides with fertilization. We present evidence that this regulation by AG is mediated by direct transcriptional repression of a master regulator of the stomatal lineage, MUTE, and show data that suggests this interaction is conserved among several members of the Brassicaceae. This work extends our understanding of the mechanisms underlying floral organ formation and provides a framework to decipher the mechanisms that control floral organ photosynthesis.
在拟南芥中，气孔由两个保卫细胞组成，它们控制中央孔的孔径，以促进植物与其环境之间的气体交换，这在光合作用过程中尤为重要。尽管叶子是开花植物的主要光合作用器官，但花器官也具有光合作用活性。在十字花科中，有证据表明，蒴果光合作用对最佳种子油含量很重要。一组包含 MADS DNA 结合结构域的转录因子是赋予花器官身份所必需的和充分的。优雅的模型，如花发育的 ABCE 模型和花四联体模型，对于描述这些花器官身份蛋白控制花发育的分子机制非常重要。然而，我们缺乏对花器官身份基因如何与潜在的叶片发育程序相互作用的完整理解。在这里，我们表明 MADS 结构域转录因子 AGAMOUS (AG) 抑制雌蕊瓣上的气孔发育，从而使气孔复合体的成熟与受精同时发生。我们提供的证据表明，AG 的这种调节是通过对气孔谱系的主调控因子 MUTE 的直接转录抑制介导的，并表明这种相互作用在几种十字花科植物中是保守的。这项工作扩展了我们对花器官形成机制的理解，并为破译控制花器官光合作用的机制提供了框架。
