Department of Plant Biology, University of California, Davis, California, USA; email:
Annu Rev Plant Biol. 2022 May 20;73:227-254. doi: 10.1146/annurev-arplant-070721-084258.
In contrast to well-studied fungal and animal cells, plant cells assemble bipolar spindles that exhibit a great deal of plasticity in the absence of structurally defined microtubule-organizing centers like the centrosome. While plants employ some evolutionarily conserved proteins to regulate spindle morphogenesis and remodeling, many essential spindle assembly factors found in vertebrates are either missing or not required for producing the plant bipolar microtubule array. Plants also produce proteins distantly related to their fungal and animal counterparts to regulate critical events such as the spindle assembly checkpoint. Plant spindle assembly initiates with microtubule nucleation on the nuclear envelope followed by bipolarization into the prophase spindle. After nuclear envelope breakdown, kinetochore fibers are assembled and unified into the spindle apparatus with convergent poles. Of note, compared to fungal and animal systems, relatively little is known about how plant cells remodel the spindle microtubule array during anaphase. Uncovering mitotic functions of novel proteins for spindle assembly in plants will illuminate both common and divergent mechanisms employed by different eukaryotic organisms to segregate genetic materials.
与研究充分的真菌和动物细胞不同，植物细胞组装出两极纺锤体，在缺乏结构定义的微管组织中心（如中心体）的情况下表现出很大的可塑性。虽然植物利用一些进化上保守的蛋白质来调节纺锤体形态发生和重塑，但在脊椎动物中发现的许多必需的纺锤体组装因子要么缺失，要么不需要产生植物两极微管阵列。植物还产生与真菌和动物对应物具有远缘关系的蛋白质，以调节关键事件，如纺锤体组装检查点。植物纺锤体组装始于核膜上的微管核形成，随后进入前期纺锤体的两极化。核膜破裂后，动粒纤维组装并与收敛的两极统一成纺锤体装置。值得注意的是，与真菌和动物系统相比，人们对植物细胞在后期如何重塑纺锤体微管阵列知之甚少。揭示植物纺锤体组装中新型蛋白质的有丝分裂功能将阐明不同真核生物用于分离遗传物质的共同和不同的机制。
