Lyndon R F, Cunninghame M E
Symp Soc Exp Biol. 1986;40:233-55.
Cell division in plants not only partitions the protoplast but also provides the architectural framework for plant form. The shape of the shoot apical meristem is produced and maintained by gradients in the rate and plane of cell division, from the summit to the base of the apical dome, which also determine the region in which primordia can be formed. In Pisum leaf initiation is mainly the result of changes in the frequency of periclinal divisions at the leaf site whereas in Silene an increase in the rate of cell division seems more important since periclinal divisions are always present. Periclinal divisions may be permissive of primordium initiation rather than causal and may define the maximum area over which primordia can form. The occurrence in Pisum and Silene of periclinal divisions which do not seem to be related to concurrent outward growth suggests that the plane of division and the direction of growth may be controlled separately and in different ways. The control of outward growth during primordium initiation may lie in the epidermis, which necessarily grows faster at the leaf site. The initial orientation of epidermal growth at the primordial site, inferred as being normal to the plane of cell division, is predominantly longitudinal in Pisum but transverse in Silene. Longitudinal growth becomes dominant later in leaf development in Silene, as in Pisum. Several lines of evidence suggest a crucial role for the epidermis in the initial stages of primordium formation although the initial orientation of division planes in it may be concerned more with the shape of the young leaf than with initiation itself. In flower initiation primordial size becomes reduced, and in Silene there are alternations of higher and lower rates of cell division in successively initiated primordial types. A fuller understanding of the role of cell division in apical growth depends on better knowledge of the functional relationships between the plane of cell division, the orientation of microtubules and wall microfibrils, and the effect that division in one cell has on its neighbours.
植物中的细胞分裂不仅将原生质体进行了分割，还为植物形态提供了架构框架。茎尖分生组织的形状是由从顶端圆顶的顶部到底部细胞分裂的速率和平面梯度产生并维持的，这些梯度也决定了原基能够形成的区域。在豌豆中，叶原基的起始主要是叶部位平周分裂频率变化的结果，而在麦瓶草中，细胞分裂速率的增加似乎更为重要，因为平周分裂始终存在。平周分裂可能允许原基起始而非导致原基起始，并且可能确定原基能够形成的最大面积。在豌豆和麦瓶草中出现的平周分裂似乎与同时发生的向外生长无关，这表明分裂平面和生长方向可能以不同方式分别受到控制。原基起始期间向外生长的控制可能在于表皮，表皮在叶部位必然生长得更快。在原基部位表皮生长的初始方向，推断为与细胞分裂平面垂直，在豌豆中主要是纵向的，而在麦瓶草中是横向的。与豌豆一样，纵向生长在麦瓶草叶片发育后期占主导地位。几条证据表明表皮在原基形成的初始阶段起关键作用，尽管其中分裂平面的初始方向可能更多地与幼叶的形状而非起始本身有关。在花原基起始时，原基大小减小，并且在麦瓶草中，相继起始的原基类型中细胞分裂速率有高低交替。对细胞分裂在顶端生长中的作用有更全面的理解，取决于对细胞分裂平面、微管和壁微纤丝的方向之间的功能关系，以及一个细胞中的分裂对其相邻细胞的影响有更好的了解。
