Rodríguez-Rodríguez José Fernando, Shishkova Svetlana, Napsucialy-Mendivil Selene, Dubrovsky Joseph G
Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, A. P. 510-3 62250 Cuernavaca Morelos, México.
Planta. 2003 Oct;217(6):849-57. doi: 10.1007/s00425-003-1055-y. Epub 2003 Jun 18.
Some species of Cactaceae from the Sonoran Desert are characterized by a determinate growth pattern of the primary root, which is important for rapid lateral-root formation and seedling establishment. An analysis of the determinate root growth can be helpful for understanding the mechanism of meristem maintenance in plants in general. Stenocereus gummosus (Engelm.) Gibson & Horak and Pachycereus pringlei (S. Watson) Britton & Rose are characterized by an open type of root apical meristem. Immunohistochemical analysis of 5-bromo-2'-deoxyuridine incorporation into S. gummosus showed that the percentage of cells passing through the S-phase in a 24-h period is the same within the zone where a population of relatively slowly proliferating cells could be established and above this zone in the meristem. This indicated the absence of the quiescent center (QC) in S. gummosus. During the second and the third days of growth, in the distal meristem portion of P. pringlei roots, a compact group of cells that had a cell cycle longer than in the proximal meristem was found, indicating the presence of the QC. However, later in development, the QC could not be detected in this species. These data suggest that during post-germination the absence of the establishment of the QC within the apical meristem and limited proliferative activity of initial cells are the main components of a determinate developmental program and that establishment of the QC is required for maintenance of the meristem and indeterminate root growth in plants.
索诺兰沙漠中的一些仙人掌科植物的特点是初生根具有有限生长模式，这对于快速形成侧根和幼苗定植很重要。分析有限根生长有助于理解一般植物中分生组织维持的机制。粘毛柱状仙人掌（Stenocereus gummosus (Engelm.) Gibson & Horak）和普氏强刺球果仙人掌（Pachycereus pringlei (S. Watson) Britton & Rose）的特点是根尖分生组织为开放型。对5-溴-2'-脱氧尿苷掺入粘毛柱状仙人掌的免疫组织化学分析表明，在可建立相对缓慢增殖细胞群体的区域内以及该区域上方的分生组织中，24小时内通过S期的细胞百分比相同。这表明粘毛柱状仙人掌中不存在静止中心（QC）。在生长的第二天和第三天，在普氏强刺球果仙人掌根的远端分生组织部分，发现了一组紧密的细胞，其细胞周期比近端分生组织中的长，表明存在静止中心。然而，在发育后期，在该物种中未检测到静止中心。这些数据表明，在种子萌发后，顶端分生组织内静止中心未建立以及初始细胞的增殖活性有限是有限发育程序的主要组成部分，并且静止中心的建立是植物分生组织维持和根的无限生长所必需的。
