Department of Plant Biology, University of California Davis, CA, USA.
Front Plant Sci. 2011 Jul 7;2:27. doi: 10.3389/fpls.2011.00027. eCollection 2011.
In angiosperms, mitosis and cytokinesis take place in the absence of structurally defined microtubule-organizing centers and the underlying mechanisms are largely unknown. In the spindle and phragmoplast, microtubule reorganization depends on microtubule-interacting factors like the γ-tubulin complex. Because of their critical functions in cell division, loss-of-function mutations in the corresponding genes are often homozygous or sporophytic lethal. However, a number of mutations like gem1, gcp2, and nedd1 can be maintained in heterozygous mutants in Arabidopsis thaliana. When mutant microspores produced by a heterozygous parent undergo pollen mitosis I, they are amenable for phenotypic characterization by fluorescence microscopy. The results would allow us to pinpoint at specific functions of particular proteins in microtubule reorganization that are characteristic to specific stages of mitosis and cytokinesis. Conclusions made in the developing microgametophytes can be extrapolated to somatic cells regarding mechanisms that regulate nuclear migration, spindle pole formation, phragmoplast assembly, and cell division plane determination.
在被子植物中，有丝分裂和胞质分裂是在没有结构定义的微管组织中心的情况下进行的，其潜在机制在很大程度上尚不清楚。在纺锤体和胞质板中，微管的重组依赖于微管相互作用因子，如γ-微管蛋白复合物。由于它们在细胞分裂中的关键功能，相应基因的功能丧失突变通常是纯合的或孢子致死的。然而，在拟南芥中，像 gem1、gcp2 和 nedd1 这样的许多突变可以在杂合突变体中被维持。当由杂合子亲本产生的突变小孢子经历花粉有丝分裂 I 时，它们可以通过荧光显微镜进行表型特征分析。这些结果将使我们能够确定特定蛋白在微管重组中的特定功能，这些功能是有丝分裂和胞质分裂特定阶段所特有的。在发育中的小配子体中得出的结论可以外推到体细胞，以了解调节核迁移、纺锤体极形成、胞质板组装和细胞分裂平面决定的机制。
