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

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

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


John Vaughan-Hirsch

Emily J. Tallerday

Christian A. Burr

Charlie Hodgens

Samantha Louise Boeshore

Kevin Beaver

Allison Melling

Kartika Sari

Associate Professor

Jan �imura

Karin Ljung

Dawei Xu

Wanqi Liang

G. Eric Schaller

Joseph J. Kieber


© 2021 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd. 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.


Vaughan-Hirsch, J., Tallerday, E. J., Burr, C. A., Hodgens, C., Louise Boeshore, S., Beaver, K., …Kieber, J. J. (2021). Function of the pseudo phosphotransfer proteins has diverged between rice and Arabidopsis. Plant Journal, 106(1), 159-173.

Journal Article Type Article
Acceptance Date Dec 3, 2020
Online Publication Date Feb 8, 2021
Publication Date 2021-04
Deposit Date Dec 7, 2020
Publicly Available Date Feb 9, 2022
Journal Plant Journal
Print ISSN 0960-7412
Electronic ISSN 1365-313X
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 106
Issue 1
Pages 159-173
Public URL
Publisher URL


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