Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom.
PLoS Biol. 2010 Nov 9;8(11):e1000537. doi: 10.1371/journal.pbio.1000537.
The mechanisms by which genes control organ shape are poorly understood. In principle, genes may control shape by modifying local rates and/or orientations of deformation. Distinguishing between these possibilities has been difficult because of interactions between patterns, orientations, and mechanical constraints during growth. Here we show how a combination of growth analysis, molecular genetics, and modelling can be used to dissect the factors contributing to shape. Using the Snapdragon (Antirrhinum) flower as an example, we show how shape development reflects local rates and orientations of tissue growth that vary spatially and temporally to form a dynamic growth field. This growth field is under the control of several dorsoventral genes that influence flower shape. The action of these genes can be modelled by assuming they modulate specified growth rates parallel or perpendicular to local orientations, established by a few key organisers of tissue polarity. Models in which dorsoventral genes only influence specified growth rates do not fully account for the observed growth fields and shapes. However, the data can be readily explained by a model in which dorsoventral genes also modify organisers of tissue polarity. In particular, genetic control of tissue polarity organisers at ventral petal junctions and distal boundaries allows both the shape and growth field of the flower to be accounted for in wild type and mutants. The results suggest that genetic control of tissue polarity organisers has played a key role in the development and evolution of shape.
基因控制器官形态的机制还知之甚少。原则上，基因可以通过改变局部变形速率和/或方向来控制形状。由于生长过程中模式、方向和机械约束之间的相互作用，区分这些可能性一直很困难。在这里，我们展示了如何结合生长分析、分子遗传学和建模来剖析导致形状形成的因素。我们以金鱼草（Antirrhinum）花为例，展示了形状发育如何反映局部组织生长的速率和方向，这些速率和方向在空间和时间上变化，形成一个动态的生长场。这个生长场受几个影响花形的背腹基因控制。这些基因的作用可以通过假设它们调节特定的生长速率与局部方向平行或垂直来建模，而局部方向由少数几个组织极性的关键组织者确定。在仅影响特定生长速率的模型中，不能完全解释观察到的生长场和形状。然而，通过一个模型可以很容易地解释数据，该模型认为背腹基因也可以改变组织极性的组织者。特别是，在侧翼花瓣交界处和远端边界处组织极性组织者的遗传控制，使得花的形状和生长场在野生型和突变体中都可以得到解释。研究结果表明，组织极性组织者的遗传控制在形状的发育和进化中发挥了关键作用。
