Raz V, Koornneef M
Laboratory of Genetics, Wageningen University, Dreijenlaan 2, 6703 HA Wageningen, The Netherlands.
Plant Physiol. 2001 Jan;125(1):219-26. doi: 10.1104/pp.125.1.219.
Growth during plant development is predominantly governed by the combined activities of cell division and cell elongation. The relative contribution of both activities controls the growth of a tissue. A fast change in growth is exhibited at the apical hypocotyl of etiolated seedlings where cells grow at different rates to form a hook-like structure, which is traditionally assumed to result from differential cell elongation. Using new tools we show asymmetric distribution of cell division during early stages of hook development. Cell divisions in the apical hook were predominantly found in subepidermal layers during an early step of hook development, but were absent in mutants exhibiting a hookless phenotype. In addition, during exaggeration of hook curvature, which is mediated by ethylene, a rapid change in the combined activities of cell division and cell elongation was detected. Our results indicate a fast change in cell division activity during apical hook development. We suggest that cell division together with cell elongation contributes to apical hook growth. Our results emphasize the change in the relative contribution of cell division and cell elongation in a fast growing structure like the apical hook.
植物发育过程中的生长主要受细胞分裂和细胞伸长共同活动的调控。这两种活动的相对贡献控制着组织的生长。在黄化幼苗的顶端下胚轴处，生长会发生快速变化，此处细胞以不同速率生长，形成一个钩状结构，传统上认为这是由细胞伸长差异导致的。使用新工具，我们发现在钩状结构发育早期细胞分裂存在不对称分布。在钩状结构发育的早期阶段，顶端钩状结构中的细胞分裂主要发生在表皮下的层中，但在表现出无钩表型的突变体中则不存在。此外，在由乙烯介导的钩状弯曲加剧过程中，检测到细胞分裂和细胞伸长的联合活动发生了快速变化。我们的结果表明顶端钩状结构发育过程中细胞分裂活动的快速变化。我们认为细胞分裂与细胞伸长共同促进顶端钩状结构的生长。我们的结果强调了在像顶端钩状结构这样快速生长的结构中，细胞分裂和细胞伸长相对贡献的变化。
