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Research article - Peer-reviewed, 2021

Function of the pseudo phosphotransfer proteins has diverged between rice and Arabidopsis

Vaughan-Hirsch, John; Tallerday, Emily J.; Burr, Christian A.; Hodgens, Charlie; Boeshore, Samantha L.; Beaver, Kevin; Melling, Allison; Sari, Kartika; Kerr, Ian D.; Simura, Jan; Ljung, Karin; Xu, Dawei; Liang, Wanqi; Bhosale, Rahul; Schaller, G. Eric; Bishopp, Anthony; Kieber, Joseph J.


The phytohormone cytokinin plays a significant role in nearly all aspects of plant growth and development. Cytokinin signaling has primarily been studied in the dicot model Arabidopsis, with relatively little work done in monocots, which include rice (Oryza sativa) and other cereals of agronomic importance. The cytokinin signaling pathway is a phosphorelay comprised of the histidine kinase receptors, the authentic histidine phosphotransfer proteins (AHPs) and type-B response regulators (RRs). Two negative regulators of cytokinin signaling have been identified: the type-A RRs, which are cytokinin primary response genes, and the pseudo histidine phosphotransfer proteins (PHPs), which lack the His residue required for phosphorelay. Here, we describe the role of the rice PHP genes. Phylogenic analysis indicates that the PHPs are generally first found in the genomes of gymnosperms and that they arose independently in monocots and dicots. Consistent with this, the three rice PHPs fail to complement an Arabidopsis php mutant (aphp1/ahp6). Disruption of the three rice PHPs results in a molecular phenotype consistent with these elements acting as negative regulators of cytokinin signaling, including the induction of a number of type-A RR and cytokinin oxidase genes. The triple php mutant affects multiple aspects of rice growth and development, including shoot morphology, panicle architecture, and seed fill. In contrast to Arabidopsis, disruption of the rice PHPs does not affect root vascular patterning, suggesting that while many aspects of key signaling networks are conserved between monocots and dicots, the roles of at least some cytokinin signaling elements are distinct.


Oryza sativa; plant hormones; cytokinin; two‐component signaling

Published in

Plant Journal
2021, volume: 106, number: 1, pages: 159-173
Publisher: WILEY

Authors' information

Vaughan-Hirsch, John
University of Nottingham
Tallerday, Emily J.
Michigan State University
Burr, Christian A.
University of North Carolina Chapel Hill
Hodgens, Charlie
University of North Carolina Chapel Hill
Boeshore, Samantha L.
University of North Carolina Chapel Hill
Beaver, Kevin
University of North Carolina Chapel Hill
Melling, Allison
University of North Carolina Chapel Hill
Sari, Kartika
University of Nottingham
Kerr, Ian D.
University of Nottingham
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Xu, Dawei
Shanghai Jiao Tong University
Liang, Wanqi
Shanghai Jiao Tong University
Bhosale, Rahul
University of Nottingham
Schaller, G. Eric
Dartmouth College
Bishopp, Anthony
University of Nottingham
Kieber, Joseph J.
University of North Carolina Chapel Hill

UKÄ Subject classification

Agricultural Science

Publication Identifiers


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