Département de Sciences Biologiques, Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke St E, Montréal, QC H1X 2B2, Canada.
Plant Physiol. 2024 Oct 1;196(2):1214-1230. doi: 10.1093/plphys/kiae408.
Plant organs have evolved into diverse shapes for specialized functions despite emerging as simple protrusions at the shoot apex. Cauline leaves serve as photosynthetic organs and protective structures for emerging floral buds. However, the growth patterns underlying this dual function remain unknown. Here, we investigate the developmental dynamics shaping Arabidopsis (Arabidopsis thaliana) cauline leaves underlying their functional diversification from other laminar organs. We show that cauline leaves display a significant delay in overall elongation compared with rosette leaves. Using live imaging, we reveal that their functional divergence hinges on early modulation of the timing of cell differentiation and cellular growth rates. In contrast to rosette leaves and sepals, cell differentiation is delayed in cauline leaves, fostering extended proliferation, prolonged morphogenetic activity, and growth redistribution within the organ. Notably, cauline leaf growth is transiently suppressed during the early stages, keeping the leaf small and unfolded during the initiation of the first flowers. Our findings highlight the unique developmental timing of cauline leaves, underlying their shift from an early protective role to a later photosynthetic function.
植物器官在进化过程中形成了多样化的形状，以适应特定的功能，尽管它们最初是在茎尖的简单突起中出现的。茎生叶是光合作用的器官和新生花芽的保护结构。然而，这种双重功能的生长模式仍然未知。在这里，我们研究了塑造拟南芥（Arabidopsis thaliana）茎生叶的发育动态，以了解它们如何从其他扁平器官中实现功能多样化。我们发现，与子叶相比，茎生叶的整体伸长明显延迟。通过活体成像，我们揭示了它们功能上的分歧取决于细胞分化和细胞生长速率的早期调节。与子叶和萼片不同，茎生叶的细胞分化延迟，促进了增殖的延长、形态发生活性的延长以及器官内的生长再分配。值得注意的是，茎生叶的生长在早期阶段会短暂受到抑制，使叶片在第一朵花的初期保持小而未展开的状态。我们的研究结果强调了茎生叶独特的发育时间，这是它们从早期保护功能转变为后期光合作用功能的基础。
