In planta functions of the Arabidopsis cytokinin receptor family
In planta functions of the Arabidopsis cytokinin receptor family
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DOI：
10.1073/pnas.0402887101
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发表时间：
2004-06-08
影响因子：
11.1
通讯作者：
Kakimoto, T
中科院分区：
文献类型：
--
作者：
Higuchi, M;Pischke, MS;Kakimoto, T
自从50年前在植物组织培养中发现细胞分裂素作为细胞分裂因子以来，细胞分裂素一直被认为在植物细胞分裂和分化的调控中起着重要作用。为了在植物中验证这一假设，我们分离了缺乏一个，两个或三个编码组氨酸激酶（CRE1，AHK2和AHK3）的亚家族的基因的拟南芥植物，这些基因起细胞分裂素受体的作用。获得种子的纯合植物含有突变的所有7种基因型，即单，双，和三重突变体，并在各种细胞分裂素测定发芽幼苗的反应进行了比较。观察到三种不同细胞分裂素受体的冗余和特异性功能。在所有三个基因携带突变的植物没有表现出细胞分裂素的反应，包括抑制根伸长，抑制根的形成，细胞增殖和愈伤组织的绿化，诱导细胞分裂素初级反应基因。三重突变体小而不育，分生组织的大小和活动减少，但他们拥有基本的器官：根，茎和叶。这些结果证实了细胞分裂素是一类关键的植物生长调节剂，但没有证据表明细胞分裂素是配子发生和胚胎发生过程所必需的。
Since their discovery as cell-division factors in plant tissue culture about five decades ago, cytokinins have been hypothesized to play a central role in the regulation of cell division and differentiation in plants. To test this hypothesis in planta, we isolated Arabidopsis plants lacking one, two, or three of the genes encoding a subfamily of histidine kinases (CRE1, AHK2, and AHK3) that function as cytokinin receptors. Seeds were obtained for homozygous plants containing mutations in all seven genotypes, namely single, double, and triple mutants, and the responses of germinated seedlings in various cytokinin assays were compared. Both redundant and specific functions for the three different cytokinin receptors were observed. Plants carrying mutations in all three genes did not show cytokinin responses, including inhibition of root elongation, inhibition of root formation, cell proliferation in and greening of calli, and induction of cytokinin primary-response genes. The triple mutants were small and infertile, with a reduction in meristem size and activity, yet they possessed basic organs: roots, stems, and leaves. These results confirm that cytokinins are a pivotal class of plant growth regulators but provide no evidence that cytokinins are required for the processes of gametogenesis and embryogenesis.