Two Arabidopsis phragmoplast-associated kinesins play a critical role in cytokinesis during male gametogenesis
Two Arabidopsis phragmoplast-associated kinesins play a critical role in cytokinesis during male gametogenesis
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DOI：
10.1105/tpc.107.050716
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发表时间：
2007-08-01
期刊：
影响因子：
11.6
通讯作者：
Liu, Bo
中科院分区：
文献类型：
--
作者：
Lee, Yuh-Ru Julie;Li, Yan;Liu, Bo
在植物细胞中，胞质分裂是由膜质体带来的。膜质体具有动态微管阵列，该动态微管阵列由两组镜像的微管组成，它们垂直于分割平面对齐，其加端位于分割部位。目前还不清楚膜质微管阵列是如何组织的。在拟南芥中，两个同源的微管运动蛋白，PAKRP1/kinesin-12A和PAKRP1L/kinesin-12B，仅定位于膜质体中部反平行微管的并列正端。当任何一种激动素被T-DNA插入敲除时，突变植物都没有表现出明显的缺陷。然而，在缺乏这两种动蛋白的情况下，雄配子体的减数分裂后发育受到严重抑制。在双突变体的小孢子分裂中，随着染色单体的分离，微管往往变得杂乱无章，无法在重整核之间形成反平行的微管阵列。因此，第一次减数分裂后的胞质分裂在没有形成细胞板的情况下被取消，这导致生殖细胞的诞生失败，随后导致精子的诞生。因此，我们的结果表明，在小孢子胞质分裂过程中，动蛋白-12A和动蛋白-12B共同在隔膜微管的组织中发挥关键作用，而胞质微管是形成细胞板的关键。此外，我们得出结论，Kinesin-12成员作为成肌体中反平行微管的正端的动态连接物。
In plant cells, cytokinesis is brought about by the phragmoplast. The phragmoplast has a dynamic microtubule array of two mirrored sets of microtubules, which are aligned perpendicularly to the division plane with their plus ends located at the division site. It is not well understood how the phragmoplast microtubule array is organized. In Arabidopsis thaliana, two homologous microtubule motor kinesins, PAKRP1/Kinesin-12A and PAKRP1L/Kinesin-12B, localize exclusively at the juxtaposing plus ends of the antiparallel microtubules in the middle region of the phragmoplast. When either kinesin was knocked out by T-DNA insertions, mutant plants did not show a noticeable defect. However, in the absence of both kinesins, postmeiotic development of the male gametophyte was severely inhibited. In dividing microspores of the double mutant, microtubules often became disorganized following chromatid segregation and failed to form an antiparallel microtubule array between reforming nuclei. Consequently, the first postmeiotic cytokinesis was abolished without the formation of a cell plate, which led to failures in the birth of the generative cell and, subsequently, the sperm. Thus, our results indicate that Kinesin-12A and Kinesin-12B jointly play a critical role in the organization of phragmoplast microtubules during cytokinesis in the microspore that is essential for cell plate formation. Furthermore, we conclude that Kinesin-12 members serve as dynamic linkers of the plus ends of antiparallel microtubules in the phragmoplast.