Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 Sherbrooke St E, Montréal, QC H1X 2B2, Canada.
Development. 2022 Jul 15;149(14). doi: 10.1242/dev.200783. Epub 2022 Jul 27.
Coordination of growth, patterning and differentiation is required for shaping organs in multicellular organisms. In plants, cell growth is controlled by positional information, yet the behavior of individual cells is often highly heterogeneous. The origin of this variability is still unclear. Using time-lapse imaging, we determined the source and relevance of cellular growth variability in developing organs of Arabidopsis thaliana. We show that growth is more heterogeneous in the leaf blade than in the midrib and petiole, correlating with higher local differences in growth rates between neighboring cells in the blade. This local growth variability coincides with developing stomata. Stomatal lineages follow a specific, time-dependent growth program that is different from that of their surroundings. Quantification of cellular dynamics in the leaves of a mutant lacking stomata, as well as analysis of floral organs, supports the idea that growth variability is mainly driven by stomata differentiation. Thus, the cell-autonomous behavior of specialized cells is the main source of local growth variability in otherwise homogeneously growing tissue. Those growth differences are buffered by the immediate neighbors of stomata and trichomes to achieve robust organ shapes.
细胞的生长、形态发生和分化的协调对于多细胞生物器官的形成至关重要。在植物中，细胞生长受位置信息的控制，但单个细胞的行为往往高度异质。这种可变性的起源尚不清楚。通过延时成像，我们确定了拟南芥发育器官中细胞生长可变性的来源和相关性。我们表明，叶片中的生长比中脉和叶柄更为异质，这与叶片中相邻细胞之间的生长速率存在更高的局部差异相关。这种局部生长可变性与正在发育的气孔相吻合。气孔谱系遵循特定的、随时间变化的生长程序，与周围环境不同。对缺乏气孔的突变体叶片中细胞动力学的定量分析以及对花器官的分析支持了这样一种观点，即生长可变性主要是由气孔分化驱动的。因此，特化细胞的细胞自主行为是其他均匀生长组织中局部生长可变性的主要来源。这些生长差异通过气孔和表皮毛的直接邻居来缓冲，以实现稳健的器官形状。
