Arabidopsis CYCD3 D-type cyclins link cell proliferation and endocycles and are rate-limiting for cytokinin responses
Arabidopsis CYCD3 D-type cyclins link cell proliferation and endocycles and are rate-limiting for cytokinin responses
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DOI：
10.1073/pnas.0704166104
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发表时间：
2007-09-04
影响因子：
11.1
通讯作者：
Murray, James A. H.
中科院分区：
文献类型：
--
作者：
Dewitte, Walter;Scofield, Simon;Murray, James A. H.
目前对植物侧生器官（如叶子）发育中细胞分裂和扩张整合的了解还有限。细胞数量在有丝分裂期建立，随后生长成成熟器官主要依赖于伴随内循环的细胞扩张。在这里，我们发现三个拟南芥细胞周期蛋白 D3 (CYCD3) 基因在发育中的侧生器官和芽分生组织中以重叠但不同的模式表达。三重功能丧失突变体表明 CYCD3 功能对于有丝分裂细胞周期和形态发生都不是必需的。相反，对突变体和相互过度表达表型的分析表明，CYCD3 功能通过调节有丝分裂期的持续时间和向内周期过渡的时间，有助于控制发育中叶片的细胞数量。花瓣通常不会进行内复制，但会通过启动内循环的较大细胞对 CYCD3 功能的丧失做出反应。植物激素细胞分裂素调节芽分生组织和发育中的叶子中的细胞分裂，并诱导 CYCD3 表达。 CYCD3 的缺失会损害芽分生组织功能并导致细胞分裂素反应降低，包括无法在愈伤组织上启动芽，而不影响内源细胞分裂素水平。我们得出的结论是，CYCD3 活性对于确定发育中的侧向器官中的细胞数量以及细胞产生和细胞扩张的替代过程对整体器官生长的相对贡献以及介导顶端生长和发育中的细胞分裂素效应非常重要。
Current understanding of the integration of cell division and expansion in the development of plant lateral organs such as leaves is limited. Cell number is established during a mitotic phase, and subsequent growth into a mature organ relies primarily on cell expansion accompanied by endocycles. Here we show that the three Arabidopsis cyclin D3 (CYCD3) genes are expressed in overlapping but distinct patterns in developing lateral organs and the shoot meristem. Triple loss-of-function mutants show that CYCD3 function is essential neither for the mitotic cell cycle nor for morphogenesis. Rather, analysis of mutant and reciprocal overexpression phenotypes shows that CYCD3 function contributes to the control of cell number in developing leaves by regulating the duration of the mitotic phase and timing of the transition to endocycles. Petals, which normally do not endoreduplicate, respond to loss of CYCD3 function with larger cells that initiate endocycles. The phytohormone cytokinin regulates cell division in the shoot meristem and developing leaves and induces CYCD3 expression. Loss of CYCD3 impairs shoot meristem function and leads to reduced cytokinin responses, including the inability to initiate shoots on callus, without affecting endogenous cytokinin levels. We conclude that CYCD3 activity is important for determining cell number in developing lateral organs and the relative contribution of the alternative processes of cell production and cell expansion to overall organ growth, as well as mediating cytokinin effects in apical growth and development.