skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Role of the Cytokinin-Activated Type-B Response Regulators in Hormone Crosstalk
Cytokinin is an important phytohormone that employs a multistep phosphorelay to transduce the signal from receptors to the nucleus, culminating in activation of type-B response regulators which function as transcription factors. Recent chromatin immunoprecipitation-sequencing (ChIP-seq) studies have identified targets of type-B ARABIDOPSIS RESPONSE REGULATORs (ARRs) and integrated these into the cytokinin-activated transcriptional network. Primary targets of the type-B ARRs are enriched for genes involved in hormonal regulation, emphasizing the extensive crosstalk that can occur between cytokinin, auxin, abscisic acid, brassinosteroids, gibberellic acid, ethylene, jasmonic acid, and salicylic acid. Examination of hormone-related targets reveals multiple regulatory points including biosynthesis, degradation/inactivation, transport, and signal transduction. Here, we consider this early response to cytokinin in terms of the hormones involved, points of regulatory crosstalk, and physiological significance.  more » « less
Award ID(s):
1856513 1856248
PAR ID:
10151630
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Plants
Volume:
9
Issue:
2
ISSN:
2223-7747
Page Range / eLocation ID:
166
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Nature Communications)
    Abstract During cell-cell communication (CCC), pathways activated by different ligand-receptor pairs may have crosstalk with each other. While multiple methods have been developed to infer CCC networks and their downstream response using single-cell RNA-seq data (scRNA-seq), the potential crosstalk between pathways connecting CCC with its downstream targets has been ignored. Here we introduce a machine learning-based method SigXTalk to analyze the crosstalk using scRNA-seq data by quantifying signal fidelity and specificity, two critical quantities measuring the effect of crosstalk. Specifically, a hypergraph learning method is used to encode the higher-order relations among receptors, transcription factors and target genes within regulatory pathways. Benchmarking of SigXTalk using simulation and real-world data shows the effectiveness, robustness, and accuracy in identifying key shared molecules among crosstalk pathways and their roles in transferring shared CCC information. Analysis of disease data shows SigXTalk’s capability in identifying crucial signals, targets, regulatory networks, and CCC patterns that distinguish different disease conditions. Applications to the data with multiple time points reveals SigXTalk’s capability in tracking the evolution of crosstalk pathways over time. Together our studies provide a systematic analysis of CCC-induced regulatory networks from the perspective of crosstalk between pathways. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, The Plant Journal)
    SUMMARY 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 ricePHPgenes. 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 ricePHPsfail to complement an Arabidopsisphpmutant (aphp1/ahp6). Disruption of the three ricePHPsresults 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 triplephpmutant affects multiple aspects of rice growth and development, including shoot morphology, panicle architecture, and seed fill. In contrast to Arabidopsis, disruption of the ricePHPsdoes 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. 
    more » « less
  3. ; ; ; ; ; (, Nature Communications)
    Abstract Structural variation in plant genomes is a significant driver of phenotypic variability in traits important for the domestication and productivity of crop species. Among these are traits that depend on functional meristems, populations of stem cells maintained by the CLAVATA-WUSCHEL (CLV-WUS) negative feedback-loop that controls the expression of the WUS homeobox transcription factor. WUS function and impact on maize development and yield remain largely unexplored. Here we show that the maize dominantBarren inflorescence3(Bif3) mutant harbors a tandem duplicated copy of theZmWUS1gene,ZmWUS1-B, whose novel promoter enhances transcription in a ring-like pattern. Overexpression ofZmWUS1-Bis due to multimerized binding sites for type-B RESPONSE REGULATORs (RRs), key transcription factors in cytokinin signaling. Hypersensitivity to cytokinin causes stem cell overproliferation and major rearrangements ofBif3inflorescence meristems, leading to the formation of ball-shaped ears and severely affecting productivity. These findings establishZmWUS1as an essential meristem size regulator in maize and highlight the striking effect of cis-regulatory variation on a key developmental program. 
    more » « less
  4. ; ; ; ; ; (, Proceedings of the National Academy of Sciences)
    The phytohormone cytokinin influences many aspects of plant growth and development, several of which also involve the cellular process of autophagy, including leaf senescence, nutrient remobilization, and developmental transitions. TheArabidopsistype-A response regulators (type-A ARR) are negative regulators of cytokinin signaling that are transcriptionally induced in response to cytokinin. Here, we describe a mechanistic link between cytokinin signaling and autophagy, demonstrating that plants modulate cytokinin sensitivity through autophagic regulation of type-A ARR proteins. Type-A ARR proteins were degraded by autophagy in an AUTOPHAGY-RELATED (ATG)5-dependent manner, and this degradation is promoted by phosphorylation on a conserved aspartate in the receiver domain of the type-A ARRs. EXO70D family members interacted with type-A ARR proteins, likely in a phosphorylation-dependent manner, and recruited them to autophagosomes via interaction of the EXO70D AIM with the core autophagy protein, ATG8. Consistently, loss-of-functionexo70D1,2,3mutants exhibited compromised targeting of type-A ARRs to autophagic vesicles, have elevated levels of type-A ARR proteins, and are hyposensitive to cytokinin. Disruption of both type-AARRsandEXO70D1,2,3compromised survival in carbon-deficient conditions, suggesting interaction between autophagy and cytokinin responsiveness in response to stress. These results indicate that the EXO70D proteins act as selective autophagy receptors to target type-A ARR cargos for autophagic degradation, demonstrating modulation of cytokinin signaling by selective autophagy. 
    more » « less
  5. ; ; (, Plant Physiology)
    Abstract Mutations in cis-regulatory regions play an important role in the domestication and improvement of crops by altering gene expression. However, assessing the in vivo impact of cis-regulatory elements (CREs) on transcriptional regulation and phenotypic outcomes remains challenging. Previously, we showed that the dominant Barren inflorescence3 (Bif3) mutant of maize (Zea mays) contains a duplicated copy of the homeobox transcription factor gene ZmWUSCHEL1 (ZmWUS1), named ZmWUS1-B. ZmWUS1-B is controlled by a spontaneously generated novel promoter region that dramatically increases its expression and alters patterning and development of young ears. Overexpression of ZmWUS1-B is caused by a unique enhancer region containing multimerized binding sites for type B RESPONSE REGULATORs (RRs), key transcription factors in cytokinin signaling. To better understand how the enhancer increases the expression of ZmWUS1 in vivo, we specifically targeted the ZmWUS1-B enhancer region by CRISPR-Cas9-mediated editing. A series of deletion events with different numbers of type B RR DNA binding motifs (AGATAT) enabled us to determine how the number of AGATAT motifs impacts in vivo expression of ZmWUS1-B and consequently ear development. In combination with dual-luciferase assays in maize protoplasts, our analysis reveals that AGATAT motifs have an additive effect on ZmWUS1-B expression, while the distance separating AGATAT motifs does not appear to have a meaningful impact, indicating that the enhancer activity derives from the sum of individual CREs. These results also suggest that in maize inflorescence development, there is a threshold of buffering capacity for ZmWUS1 overexpression. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email