The Arabidopsis CDK inhibitor ICK3/KRP5 is rate limiting for primary root growth and promotes growth through cell elongation and endoreduplication.
The Arabidopsis CDK inhibitor ICK3/KRP5 is rate limiting for primary root growth and promotes growth through cell elongation and endoreduplication.
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DOI：
10.1093/jxb/ert009
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发表时间：
2013-02
影响因子：
6.9
通讯作者：
Murray JA
中科院分区：
文献类型：
--
作者：
Wen B;Nieuwland J;Murray JA
植物细胞分裂和扩展的协调控制着植物的形态发生、发育和生长。细胞周期蛋白依赖性激酶（Cyclin-dependent kinases，CDKs）不仅是细胞分裂的关键调节因子，而且在细胞分化中起重要作用。在植物中，CDK活性通过CDK/KIP相关蛋白抑制剂（ICK/KRP）的结合来调节。以前，ICK 2/KRP 2已被证明介导侧根发生中的生长素反应。本文分析了ICK/KRP基因在根生长中的作用。对ick/krp缺失突变体的分析表明，只有ick 3/krp 5对初生根的生长有影响。ICK 3/KRP 5在根尖分生组织（RAM）中强烈表达，在扩展区中表达较低。ick 3/krp 5根比野生型对照生长得更慢，这不是由于RAM增殖区域的分裂减少，而是由于细胞退出分生组织时扩展减少。这导致ick 3/krp 5突变体根的不同组织中的最终细胞长度变短，特别是表皮非毛细胞，并且这种细胞大小的减小与减少的核内复制相关。ICK 3/KRP 5的缺失也导致延迟的萌发，并且在成熟胚中，ICK 3/KRP 5在根和下胚轴之间的过渡区中特异性表达。尽管在胚胎中没有核内复制，但在ick 3/krp 5突变体中过渡区中的细胞较小，这表明ICK 3/KRP 5对细胞生长有直接影响。结论：ICK 3/KRP 5是细胞生长和核内复制的正调节因子。
The coordination of plant cell division and expansion controls plant morphogenesis, development, and growth. Cyclin-dependent kinases (CDKs) are not only key regulators of cell division but also play an important role in cell differentiation. In plants, CDK activity is modulated by the binding of INHIBITOR OF CDK/KIP-RELATED PROTEIN (ICK/KRP). Previously, ICK2/KRP2 has been shown to mediate auxin responses in lateral root initiation. Here are analysed the roles of all ICK/KRP genes in root growth. Analysis of ick/krp null-mutants revealed that only ick3/krp5 was affected in primary root growth. ICK3/KRP5 is strongly expressed in the root apical meristem (RAM), with lower expression in the expansion zone. ick3/krp5 roots grow more slowly than wildtype controls, and this results not from reduction of division in the proliferative region of the RAM but rather reduced expansion as cells exit the meristem. This leads to shorter final cell lengths in different tissues of the ick3/krp5 mutant root, particularly the epidermal non-hair cells, and this reduction in cell size correlates with reduced endoreduplication. Loss of ICK3/KRP5 also leads to delayed germination and in the mature embryo ICK3/KRP5 is specifically expressed in the transition zone between root and hypocotyl. Cells in the transition zone were smaller in the ick3/krp5 mutant, despite the absence of endoreduplication in the embryo suggesting a direct effect of ICK3/KRP5 on cell growth. It is concluded that ICK3/KRP5 is a positive regulator of both cell growth and endoreduplication.
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影响因子：
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