Syngenta Biotechnology Inc., Research Triangle Park NC, USA.
Department of Biology, Stanford University Stanford, CA, USA.
Front Plant Sci. 2014 Jul 21;5:347. doi: 10.3389/fpls.2014.00347. eCollection 2014.
Compared to the diversity of other floral organs, the steps in anther ontogeny, final cell types, and overall organ shape are remarkably conserved among Angiosperms. Defects in pre-meiotic anthers that alter cellular composition or function typically result in male-sterility. Given the ease of identifying male-sterile mutants, dozens of genes with key roles in early anther development have been identified and cloned in model species, ordered by time of action and spatiotemporal expression, and used to propose explanatory models for critical steps in cell fate specification. Despite rapid progress, fundamental issues in anther development remain unresolved, and it is unclear if insights from one species can be applied to others. Here we construct a comparison of Arabidopsis, rice, and maize immature anthers to pinpoint distinctions in developmental pace. We analyze the mechanisms by which archesporial (pre-meiotic) cells are specified distinct from the soma, discuss what constitutes meiotic preparation, and review what is known about the secondary parietal layer and its terminal periclinal division that generates the tapetal and middle layers. Finally, roles for small RNAs are examined, focusing on the grass-specific phasiRNAs.
与其他花器官的多样性相比，花药的个体发生、最终细胞类型和整体器官形态在被子植物中惊人地保守。改变细胞组成或功能的减数分裂前花药缺陷通常导致雄性不育。鉴于雄性不育突变体易于识别，已在模式物种中鉴定和克隆了数十个在早期花药发育中起关键作用的基因，按作用时间和时空表达顺序排列，并用于提出细胞命运特化关键步骤的解释模型。尽管取得了快速进展，但花药发育中的基本问题仍未解决，并且不清楚一个物种的见解是否可以应用于其他物种。在这里，我们构建了拟南芥、水稻和玉米未成熟花药的比较，以确定发育速度的差异。我们分析了与体细胞不同的孢原细胞（减数分裂前）的特化机制，讨论了减数分裂准备的构成，回顾了关于次生壁层及其产生绒毡层和中层的末端平周分裂的已知内容。最后，检查了小 RNA 的作用，重点是草特异性的 phasiRNAs。
