Histidine Kinases and Cytokinin Signaling: Molecular Architecture, Evolution, and Functional Roles in Plant Development and Environmental Adaptation

Title

Histidine Kinases and Cytokinin Signaling: Molecular Architecture, Evolution, and Functional Roles in Plant Development and Environmental Adaptation

Author

1. Nadir Durrani, Postdoctoral Researcher, National University of Laos, Laos
2. Pakorn Homechai, Professor, National University of Laos, Laos

Abstract

Histidine kinases (HKs) represent a core component of plant two-component signaling systems and serve as primary receptors for cytokinins, enabling plants to perceive developmental cues and respond to environmental stress. Recent studies have substantially expanded the understanding of HK diversification, receptor evolution, ligand-binding properties, and downstream signaling mechanisms, revealing their essential roles in regulating organogenesis, meristem activity, senescence, root–shoot communication, and responses to abiotic stresses. CHASE-domain-containing receptors have emerged as critical sensors with specialized cytokinin-binding capacities across species, while novel work has clarified the broad distribution and functional specificity of sensor HKs in eukaryotes. Additionally, receptor-like protein kinases (RLKs) have been implicated in complementary and overlapping functions during abiotic stress acclimation, further integrating hormonal, metabolic, and environmental signals. This review synthesizes current advances in HK biology, cytokinin receptor evolution, molecular structure, physiological functions, and their involvement in developmental processes such as shoot organogenesis, leaf aging, embryonic patterning, and environmental adaptation. By consolidating findings across Arabidopsis, maize, apple, and other model systems, this paper highlights new insights into the complexity of HK signaling pathways and proposes future research directions for developmental biology and stress physiology.

Keywords

Conclusion

Histidine kinases represent one of the most versatile and evolutionarily significant signaling families in plants. Their dual roles in development and environmental responses position them as central integrators of internal and external cues. The diversity of cytokinin receptors and CHASE-domain-containing HKs across species underlies the complexity of developmental regulation, while recent advances highlight their contributions to stress adaptation, senescence, organogenesis, and meristem function.

Future research should focus on high-resolution structural analyses of HK–ligand interactions, tissue-specific receptor functions, HK-mediated crosstalk with other hormonal pathways, and the integration of omics approaches to map HK signaling networks. Understanding the evolutionary trajectories of HK diversification may reveal new insights into plant development and resilience, offering potential applications in crop improvement, stress tolerance engineering, and developmental control.

Author Contrubution

The study's design, data collection, result analysis, and manuscript preparation were entirely managed by the author.

Funding

No specific grants from any funding agencies in the public, commercial, or non-profit sectors were received for this research, authorship, or publication.

Conflict of Interest

The authors disclose no conflicts of interest in relation to this work.

Data Sharing Statement

Not applicable.

Software And Tools Use

Not applicable.

Acknowledgements

I appreciate the assistance and expertise provided by everyone involved in this research and manuscript, and the valuable comments from peer reviewers.