Galipot Pierre, Gerber Sylvain, Le Guilloux Martine, Jabbour Florian, Damerval Catherine
Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, France.
Génétique Quantitative et Evolution-Le Moulon, Université Paris-Saclay, INRAE, CNRS, AgroParisTech, Gif-sur-Yvette, France.
Front Plant Sci. 2021 Nov 19;12:769246. doi: 10.3389/fpls.2021.769246. eCollection 2021.
Petals, the inner organs in a differentiated perianth, generally play an important role in pollinator attraction. As such they exhibit an extraordinary diversity of shapes, sizes, and colors. Being involved in pollinator attraction and reward, they are privileged targets of evolution. The corolla of the Ranunculaceae species consists of elaborate nectariferous petals, made of a stalk, upper, and lower lips forming a nectar pouch, shiny pseudonectaries, and pilose ears. While the main events of petal development are properly described, a few is known about the pattern of organ size and shape covariation and the cellular dynamics during development. In this study, we investigated the relationships between morphogenesis and growth of petals using geometric morphometrics coupled with the study of cell characteristics. First, we found that petal shape and size dynamics are allometric during development and that their covariation suggests that petal shape change dynamics are exponentially slower than growth. We then found that cell proliferation is the major driver of shape patterning during development, while petal size dynamics are mostly driven by cell expansion. Our analyses provide a quantitative basis to characterize the relationships between shape, size, and cell characteristics during the development of an elaborate floral structure. Such studies lay the ground for future evo-devo investigations of the large morphological diversity observed in nectariferous structures, in Ranunculaceae and beyond.
花瓣作为分化花被中的内部器官，通常在吸引传粉者方面发挥重要作用。因此，它们呈现出形状、大小和颜色的非凡多样性。由于参与吸引传粉者并提供回报，它们成为了进化的优先目标。毛茛科植物的花冠由精致的分泌花蜜的花瓣组成，花瓣由一个花柄、上唇和下唇构成一个花蜜袋、闪亮的假蜜腺以及具柔毛的耳状物。虽然花瓣发育的主要过程已有恰当描述，但关于器官大小和形状协变模式以及发育过程中的细胞动态却知之甚少。在本研究中，我们结合细胞特征研究，运用几何形态测量学来探究花瓣形态发生与生长之间的关系。首先，我们发现花瓣形状和大小动态在发育过程中呈异速生长，且它们的协变表明花瓣形状变化动态比生长慢得多。然后我们发现细胞增殖是发育过程中形状形成的主要驱动力，而花瓣大小动态主要由细胞扩张驱动。我们的分析为描述复杂花结构发育过程中形状、大小和细胞特征之间的关系提供了定量依据。此类研究为未来对毛茛科及其他类群中分泌花蜜结构所观察到的巨大形态多样性进行演化发育研究奠定了基础。
