D-type cyclins activate division in the root apex to promote seed germination in Arabidopsis
D-type cyclins activate division in the root apex to promote seed germination in Arabidopsis
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DOI：
10.1073/pnas.0507581102
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发表时间：
2005-10-25
影响因子：
11.1
通讯作者：
Murray, JAH
中科院分区：
文献类型：
--
作者：
Masubelele, NH;Dewitte, W;Murray, JAH
种子通过保护休眠的成熟植物胚胎提供生存和传播能力。在有利的条件下萌发和恢复发育需要通过鲜为人知的过程重新启动细胞的生长和分裂。在这里，我们证明了拟南芥萌发过程中细胞分裂激活的四个阶段与外部形态变化有关。细胞分裂始于根的顶端分生组织(RAM)，然后在子叶、茎尖分生组织(SAM)和次生分生组织中依次激活细胞分裂。在根出现之前，>；2,000基因转录水平的主要变化，包括六个D型(Cycd)和两个A型周期蛋白的表达高峰。随后还会用SAM激活另外两个CyCD。早期激活的CyCDs在调节细胞分裂程度方面起着关键作用，因为早期CyCDs的功能缺失等位基因表现为分裂激活减少，从而延迟了根的出现。相反，早期CyCDs的升高增加了RAM中细胞周期的激活，并促进了胚根(根)的突起，而后期作用的CyCDs并非如此。这些表型与其重叠的表达结构域一起，支持细胞周期再激活中的一部分CyCDs的累积作用，而不是完全的功能冗余。这一分析揭示了与植物细胞周期蛋白功能丧失相关的表型，并表明D型细胞周期蛋白在分生组织激活过程中调节细胞周期重新进入，以促进成功萌发和早期幼苗生长。
Seeds provide survival and dispersal capabilities by protecting the dormant mature plant embryo. Germination and resumption of development under favourable conditions requires the reinitiation of cell growth and division through poorly understood processes. Here we show that four phases of cell division activation during germination in Arabidopsis are related to external morphological changes. Cell division initiates in the root apical meristem (RAM) before root protrusion, followed by sequential activation of cell division in the cotyledons, shoot apical meristem (SAM), and secondary meristems. Major changes in transcript levels of >2,000 genes precede root emergence, including expression peaks of six D-type (CYCD) and two A-type cyclins. Two further CYCDs are activated later with the SAM. Early activated CYCDs play key roles in regulating the extent of cell division, because loss-of-function alleles of early CYCDs display reduced division activation and consequential delayed root emergence. Conversely, elevation of early CYCDs increases cell cycle activation in the RAM and promotes embryonic root (radicle) protrusion, whereas a later-acting CYCD does not. These phenotypes, together with their overlapping expression domains, support a cumulative action of a subset of CYCDs in cell cycle reactivation, rather than a complete functional redundancy. This analysis reveals a phenotype associated with loss-of-function of a plant cyclin and demonstrates that D-type cyclins regulate cell cycle reentry during meristem activation to promote successful germination and early seedling growth.