The Histidine Kinases CYTOKININ-INDEPENDENT1 and ARABIDOPSIS HISTIDINE KINASE2 and 3 Regulate Vascular Tissue Development in Arabidopsis Shoots
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Periodical |
| Magazine / Source | Plant Cell |
| MU Faculty or unit | |
| Citation | |
| Field | Genetics and molecular biology |
| Keywords | Histidine kinases CKI1 |
| Description | 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 sensor histidine kinase CKI1 and the cytokinin receptors AHK2 and AHK3 are important regulators of vascular tissue development in Arabidopsis shoots. Genetic modifications of CKI1 activity in Arabidopsis causes dysfunction of the two-component signaling pathway and defects in procambial cell maintenance and/or identity. CKI1 overexpression in protoplasts leads to cytokinin-independent activation of the two-component phosphorelay, and intracellular domains are responsible for cytokinin-independent activity of CKI1. CKI1 expression is restricted to vascular tissues in 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. These results indicate that the cytokinin-independent activity of CKI1 and cytokinin-induced AHK2 and AHK3 are important for vascular bundle formation and biomass production in Arabidopsis. |
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