The Histidine Kinases CYTOKININ-INDEPENDENT1 and ARABIDOPSIS HISTIDINE KINASE2 and 3 Regulate Vascular Tissue Development in Arabidopsis Shoots
The Histidine Kinases CYTOKININ-INDEPENDENT1 and ARABIDOPSIS HISTIDINE KINASE2 and 3 Regulate Vascular Tissue Development in Arabidopsis Shoots
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DOI：
10.1105/tpc.109.066696
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发表时间：
2009-07-01
期刊：
影响因子：
11.6
通讯作者：
Hwang, Ildoo
中科院分区：
文献类型：
--
作者：
Hejatko, Jan;Ryu, Hojin;Hwang, Ildoo
原形成层和形成层的发育和活性确保维管组织的形成，对于整体植物结构和生长至关重要。然而，人们对影响维管分生组织活性和维管组织形成的分子因素知之甚少。在这里，我们发现组氨酸激酶细胞分裂素独立1（CKI1）和细胞分裂素受体拟南芥组氨酸激酶2（AHK2）和AHK3是拟南芥芽中维管组织发育的重要调节因子。拟南芥中 CKI1 活性的基因修饰导致双组分信号通路功能障碍和原形成层细胞维护缺陷。原生质体中 CKI1 的过表达导致双组分磷酸中继的细胞分裂素依赖性激活，而细胞内结构域负责 CKI1 的细胞分裂素依赖性活性。在花序茎的维管组织中观察到 CKI1 表达，并且 CKI1 在体外和植物中均形成同二聚体。功能丧失的 ahk2 和 ahk3 突变体以及内源细胞分裂素水平降低的植物表现出原形成层增殖缺陷和二次生长缺失。 CKI1 过表达部分挽救了血管组织中的 ahk2 ahk3 表型，而负突变 CKI1(H405Q) 进一步加剧了突变表型。这些结果表明，CKI1 的细胞分裂素独立活性和细胞分裂素诱导的 AHK2 和 AHK3 对于拟南芥中维管束的形成非常重要。
The development and activity of the procambium and cambium, which ensure vascular tissue formation, is critical for overall plant architecture and growth. However, little is known about the molecular factors affecting the activity of vascular meristems and vascular tissue formation. Here, we show that the His kinase CYTOKININ-INDEPENDENT1 (CKI1) and the cytokinin receptors ARABIOPSIS HISTIDINE KINASE2 (AHK2) and AHK3 are important regulators of vascular tissue development in Arabidopsis thaliana shoots. Genetic modifications of CKI1 activity in Arabidopsis cause dysfunction of the two-component signaling pathway and defects in procambial cell maintenance. CKI1 overexpression in protoplasts leads to cytokinin-independent activation of the two-component phosphorelay, and intracellular domains are responsible for the cytokinin-independent activity of CKI1. CKI1 expression is observed in vascular tissues of inflorescence stems, and CKI1 forms homodimers both in vitro and in planta. Loss-of-function ahk2 and ahk3 mutants and plants with reduced levels of endogenous cytokinins show defects in procambium proliferation and an absence of secondary growth. CKI1 overexpression partially rescues ahk2 ahk3 phenotypes in vascular tissue, while the negative mutation CKI1(H405Q) further accentuates mutant phenotypes. These results indicate that the cytokinin-independent activity of CKI1 and cytokinin-induced AHK2 and AHK3 are important for vascular bundle formation in Arabidopsis.