Analysis of leaf development in fugu mutants of Arabidopsis reveals three compensation modes that modulate cell expansion in determinate organs
Analysis of leaf development in fugu mutants of Arabidopsis reveals three compensation modes that modulate cell expansion in determinate organs
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DOI：
10.1104/pp.107.099325
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发表时间：
2007-06-01
期刊：
影响因子：
7.4
通讯作者：
Tsukaya, Hirokazu
中科院分区：
文献类型：
--
作者：
Ferjani, Ali;Horiguchi, Gorou;Tsukaya, Hirokazu
在多细胞生物体中，细胞增殖和扩张的协调是适当的器官发生的基础，但这种协调所涉及的分子机制在很大程度上还没有被探索。在植物叶片中，这种协调的存在是通过补偿来表明的，在这种补偿中，细胞数量的减少触发了成熟细胞大小的增加。为了阐明补偿机制，我们分离了5个新的拟南芥突变体(fugu1-fugu5)。这些突变体与ANGUSTIFOLIA3(AN3)、ERECTA(ER)和KIP相关的PROTEIN2(KRP2)过表达一起被鉴定，以前有报道显示它们具有补偿作用。叶片发育的时间进程分析表明，在Fugu2-1、Fugu5-1、AN3-4和er-102突变体中，细胞扩张是在有丝分裂后诱导的，表明细胞扩张不是由细胞分裂和细胞生长的解偶联引起的。在每个突变体中，细胞扩张的速度或持续时间都有选择地增强。相反，我们发现KRP2过表达的细胞在细胞增殖过程中促进了细胞的扩张。我们进一步证明，增强的细胞扩张发生在子叶中，其动力学类似于叶片。相反，尽管根部的细胞数量减少，但细胞扩张并未得到增强。因此，补偿被证实优先发生在确定的器官中。流式细胞仪分析表明，倍性水平的增加并不总是触发补偿的必要条件，这表明补偿仅部分通过倍性依赖的过程来调节。我们的结果表明，代偿反映了特定器官中细胞增殖和扩张的器官范围内的协调，至少涉及三种不同的扩张途径。
In multicellular organisms, the coordination of cell proliferation and expansion is fundamental for proper organogenesis, yet the molecular mechanisms involved in this coordination are largely unexplored. In plant leaves, the existence of this coordination is suggested by compensation, in which a decrease in cell number triggers an increase in mature cell size. To elucidate the mechanisms of compensation, we isolated five new Arabidopsis (Arabidopsis thaliana) mutants (fugu1 -fugu5) that exhibit compensation. These mutants were characterized together with angustifolia3 (an3), erecta (er), and a KIP-RELATED PROTEIN2 (KRP2) overexpressor, which were previously reported to exhibit compensation. Time-course analyses of leaf development revealed that enhanced cell expansion in fugu2-1, fugu5-1, an3-4, and er-102 mutants is induced postmitotically, indicating that cell enlargement is not caused by the uncoupling of cell division from cell growth. In each of the mutants, either the rate or duration of cell expansion was selectively enhanced. In contrast, we found that enhanced cell expansion in KRP2 overexpressor occurs during cell proliferation. We further demonstrated that enhanced cell expansion occurs in cotyledons with dynamics similar to that in leaves. In contrast, cell expansion was not enhanced in roots even though they exhibit decreased cell numbers. Thus, compensation was confirmed to occur preferentially in determinate organs. Flow cytometric analyses revealed that increases in ploidy level are not always required to trigger compensation, suggesting that compensation is only partially mediated by ploidy-dependent processes. Our results suggest that compensation reflects an organ-wide coordination of cell proliferation and expansion in determinate organs, and involves at least three different expansion pathways.