ArabidopsisHistidine Kinase CKI1 Acts Upstream of HISTIDINE PHOSPHOTRANSFER PROTEINS to Regulate Female Gametophyte Development and Vegetative Growth
Open Access
- 1 April 2010
- journal article
- Published by Oxford University Press (OUP) in Plant Cell
- Vol. 22 (4), 1232-1248
- https://doi.org/10.1105/tpc.108.065128
Abstract
Cytokinin signaling is mediated by a multiple-step phosphorelay. Key components of the phosphorelay consist of the histidine kinase (HK)-type receptors, histidine phosphotransfer proteins (HP), and response regulators (RRs). Whereas overexpression of a nonreceptor-type HK gene CYTOKININ-INDEPENDENT1 (CKI1) activates cytokinin signaling by an unknown mechanism, mutations in CKI1 cause female gametophytic lethality. However, the function of CKI1 in cytokinin signaling remains unclear. Here, we characterize a mutant allele, cki1-8, that can be transmitted through female gametophytes with low frequency (∼0.17%). We have recovered viable homozygous cki1-8 mutant plants that grow larger than wild-type plants, show defective megagametogenesis and rarely set enlarged seeds. We found that CKI1 acts upstream of AHP (Arabidopsis HP) genes, independently of cytokinin receptor genes. Consistently, an ahp1,2-2,3,4,5 quintuple mutant, which contains an ahp2-2 null mutant allele, exhibits severe defects in megagametogenesis, with a transmission efficiency of ahp1,2-2,3,4,5 quintuple mutants are seedling lethal. Finally, the female gametophytic lethal phenotype of cki1-5 (a null mutant) can be partially rescued by IPT8 or ARR1 (a type-B Arabidopsis RR) driven by a CKI1 promoter. These results define a genetic pathway consisting of CKI1, AHPs, and type-B ARRs in the regulation of female gametophyte development and vegetative growth.Keywords
This publication has 49 references indexed in Scilit:
- The Histidine Kinases CYTOKININ-INDEPENDENT1 and ARABIDOPSIS HISTIDINE KINASE2 and 3 Regulate Vascular Tissue Development inArabidopsisShootsPlant Cell, 2009
- Cloning, purification, crystallization and preliminary X-ray analysis of the receiver domain of the histidine kinase CKI1 fromArabidopsis thalianaActa Crystallographica Section F Structural Biology and Crystallization Communications, 2009
- Analysis of theArabidopsisHistidine Kinase ATHK1 Reveals a Connection between Vegetative Osmotic Stress Sensing and Seed MaturationPlant Cell, 2008
- Functional analysis of AHK1/ATHK1 and cytokinin receptor histidine kinases in response to abscisic acid, drought, and salt stress in ArabidopsisProceedings of the National Academy of Sciences of the United States of America, 2007
- The Central Cell Plays a Critical Role in Pollen Tube Guidance inArabidopsisPlant Cell, 2007
- Functional Characterization of the Arabidopsis Eukaryotic Translation Initiation Factor 5A-2 That Plays a Crucial Role in Plant Growth and Development by Regulating Cell Division, Cell Growth, and Cell DeathPlant Physiology, 2007
- TheArabidopsisHistidine Phosphotransfer Proteins Are Redundant Positive Regulators of Cytokinin SignalingPlant Cell, 2006
- Cytokinin biosynthesis and perceptionPhysiologia Plantarum, 2006
- Two-component circuitry in Arabidopsis cytokinin signal transductionNature, 2001
- Possible His to Asp phosphorelay signaling in an Arabidopsis two‐component systemFEBS Letters, 2000