Kwiatkowska Dorota
Institute of Plant Biology, Wrocław University, Kanonia 6/8, 50-328 Wrocław, Poland.
J Exp Bot. 2006;57(3):571-80. doi: 10.1093/jxb/erj042. Epub 2005 Dec 23.
Geometry changes, especially surface expansion, accompanying flower primordium formation are investigated at the reproductive shoot apex of Arabidopsis with the aid of a non-invasive replica method and a 3-D reconstruction algorithm. The observed changes are characteristic enough to differentiate the early development of flower primordium in Arabidopsis into distinct stages. Primordium formation starts from the fast and anisotropic growth at the periphery of the shoot apical meristem, with the maximum extension in the meridional direction. Surprisingly, the primordium first becomes a shallow crease, and it is only later that this shape changes into a bulge. The bulge is formed from the shallow crease due to slower and less anisotropic growth than at the onset of primordium formation. It is proposed that the shallow crease is the first axil, i.e. the axil of a putative rudimentary bract subtending the flower primordium proper, while the flower primordium proper is the bulge formed at the bottom of this axil. At the adaxial side of the bulge, the second axil (a narrow and deep crease) is formed setting the boundary between the flower primordium proper and the shoot apical meristem. Surface growth, leading to the formation of the second axil, is slow and anisotropic. This is similar to the previously described growth pattern at the boundary of the leaf primordium in Anagallis.
借助非侵入性复制品方法和三维重建算法，在拟南芥生殖茎尖研究了伴随花原基形成的几何变化，尤其是表面扩展。观察到的变化具有足够的特征，可将拟南芥花原基的早期发育分为不同阶段。原基形成始于茎尖分生组织周边的快速且各向异性生长，在子午方向上扩展最大。令人惊讶的是，原基首先变成一条浅折痕，只是在后来这种形状才变为凸起。该凸起是由浅折痕形成的，其生长速度比原基形成开始时更慢且各向异性更小。有人提出浅折痕是第一个叶腋，即位于花原基下方的一个假定的退化苞片的叶腋，而花原基本身是在这个叶腋底部形成的凸起。在凸起的近轴侧，形成了第二个叶腋（一条狭窄且深的折痕），它界定了花原基本身与茎尖分生组织之间的边界。导致第二个叶腋形成的表面生长缓慢且各向异性。这与之前描述的报春花属植物叶原基边界处的生长模式相似。
