1
|
Liu L, Yahaya BS, Li J, Wu F. Enigmatic role of auxin response factors in plant growth and stress tolerance. FRONTIERS IN PLANT SCIENCE 2024; 15:1398818. [PMID: 38903418 PMCID: PMC11188990 DOI: 10.3389/fpls.2024.1398818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 05/23/2024] [Indexed: 06/22/2024]
Abstract
Abiotic and biotic stresses globally constrain plant growth and impede the optimization of crop productivity. The phytohormone auxin is involved in nearly every aspect of plant development. Auxin acts as a chemical messenger that influences gene expression through a short nuclear pathway, mediated by a family of specific DNA-binding transcription factors known as Auxin Response Factors (ARFs). ARFs thus act as effectors of auxin response and translate chemical signals into the regulation of auxin responsive genes. Since the initial discovery of the first ARF in Arabidopsis, advancements in genetics, biochemistry, genomics, and structural biology have facilitated the development of models elucidating ARF action and their contributions to generating specific auxin responses. Yet, significant gaps persist in our understanding of ARF transcription factors despite these endeavors. Unraveling the functional roles of ARFs in regulating stress response, alongside elucidating their genetic and molecular mechanisms, is still in its nascent phase. Here, we review recent research outcomes on ARFs, detailing their involvement in regulating leaf, flower, and root organogenesis and development, as well as stress responses and their corresponding regulatory mechanisms: including gene expression patterns, functional characterization, transcriptional, post-transcriptional and post- translational regulation across diverse stress conditions. Furthermore, we delineate unresolved questions and forthcoming challenges in ARF research.
Collapse
Affiliation(s)
- Ling Liu
- Faculty of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, Sichuan, China
| | - Baba Salifu Yahaya
- Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, China
- Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Wenjiang, Sichuan, China
| | - Jing Li
- Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, China
- Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Wenjiang, Sichuan, China
| | - Fengkai Wu
- Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, China
- Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Wenjiang, Sichuan, China
| |
Collapse
|
2
|
Cohen JD, Strader LC. An auxin research odyssey: 1989-2023. THE PLANT CELL 2024; 36:1410-1428. [PMID: 38382088 PMCID: PMC11062468 DOI: 10.1093/plcell/koae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/23/2024] [Accepted: 02/07/2024] [Indexed: 02/23/2024]
Abstract
The phytohormone auxin is at times called the master regulator of plant processes and has been shown to be a central player in embryo development, the establishment of the polar axis, early aspects of seedling growth, as well as growth and organ formation during later stages of plant development. The Plant Cell has been key, since the inception of the journal, to developing an understanding of auxin biology. Auxin-regulated plant growth control is accomplished by both changes in the levels of active hormones and the sensitivity of plant tissues to these concentration changes. In this historical review, we chart auxin research as it has progressed in key areas and highlight the role The Plant Cell played in these scientific developments. We focus on understanding auxin-responsive genes, transcription factors, reporter constructs, perception, and signal transduction processes. Auxin metabolism is discussed from the development of tryptophan auxotrophic mutants, the molecular biology of conjugate formation and hydrolysis, indole-3-butyric acid metabolism and transport, and key steps in indole-3-acetic acid biosynthesis, catabolism, and transport. This progress leads to an expectation of a more comprehensive understanding of the systems biology of auxin and the spatial and temporal regulation of cellular growth and development.
Collapse
Affiliation(s)
- Jerry D Cohen
- Department of Horticultural Science and the Microbial and Plant Genomics Institute, University of Minnesota, Saint Paul, MN 55108, USA
| | - Lucia C Strader
- Department of Biology, Duke University, Durham, NC 27008, USA
| |
Collapse
|
3
|
Kim SH, Yoon J, Kim H, Lee SJ, Kim T, Kang K, Paek NC. OsMYB7 determines leaf angle at the late developmental stage of lamina joints in rice. FRONTIERS IN PLANT SCIENCE 2023; 14:1167202. [PMID: 37123839 PMCID: PMC10140434 DOI: 10.3389/fpls.2023.1167202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/27/2023] [Indexed: 05/03/2023]
Abstract
Leaf angle shapes plant architecture, allowing for optimal light interception to maximize photosynthesis and yield, and therefore is a crucial agronomic trait. Here, we show that the rice (Oryza sativa L.) R2R3-type MYB transcription factor OsMYB7 determines leaf angle in a developmental stage-specific manner. OsMYB7-overexpressing lines produced wide-angled leaves and osmyb7 knockout mutants exhibited erect leaves. This phenotype was restricted to the lamina joints at the late developmental stage. In agreement with these observations, OsMYB7 was preferentially expressed in the lamina joints of post-mature leaves. Since OsMYB7 homologs are transcriptional repressors of lignin biosynthesis, we examined whether OsMYB7 might inhibit thickening of secondary cell walls. Although OsMYB7 repressed lignin biosynthesis, it enhanced thickening of sclerenchyma cell walls by elevating cellulose contents at the lamina joints. Furthermore, we found that OsMYB7 affects endogenous auxin levels in lamina joints, and the adaxial cells of lamina joints in OsMYB7-overexpressing lines and osmyb7 knockout mutants exhibited enhanced and reduced elongation, respectively, compared to the wild type. These results suggest that OsMYB7 promotes leaf inclination partially through decreasing free auxin levels and promoting cell elongation at the adaxial side of lamina joints.
Collapse
Affiliation(s)
- Suk-Hwan Kim
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jungwon Yoon
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hanna Kim
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Sang-Ji Lee
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Taehoon Kim
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Kiyoon Kang
- Division of Life Sciences, Incheon National University, Incheon, Republic of Korea
| | - Nam-Chon Paek
- Department of Agriculture, Forestry and Bioresources, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
- *Correspondence: Nam-Chon Paek,
| |
Collapse
|
4
|
Aux/IAA11 Is Required for UV-AB Tolerance and Auxin Sensing in Arabidopsis thaliana. Int J Mol Sci 2022; 23:ijms232113386. [PMID: 36362171 PMCID: PMC9655273 DOI: 10.3390/ijms232113386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 10/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
In order to survive, plants have, over the course of their evolution, developed sophisticated acclimation and defense strategies governed by complex molecular and physiological, and cellular and extracellular, signaling pathways. They are also able to respond to various stimuli in the form of tropisms; for example, phototropism or gravitropism. All of these retrograde and anterograde signaling pathways are controlled and regulated by waves of reactive oxygen species (ROS), electrical signals, calcium, and hormones, e.g., auxins. Auxins are key phytohormones involved in the regulation of plant growth and development. Acclimation responses, which include programmed cell death induction, require precise auxin perception. However, our knowledge of these pathways is limited. The Aux/IAA family of transcriptional corepressors inhibits the growth of the plant under stress conditions, in order to maintain the balance between development and acclimation responses. In this work, we demonstrate the Aux/IAA11 involvement in auxin sensing, survival, and acclimation to UV-AB, and in carrying out photosynthesis under inhibitory conditions. The tested iaa11 mutants were more susceptible to UV-AB, photosynthetic electron transport (PET) inhibitor, and synthetic endogenous auxin. Among the tested conditions, Aux/IAA11 was not repressed by excess light stress, exclusively among its phylogenetic clade. Repression of transcription by Aux/IAA11 could be important for the inhibition of ROS formation or efficiency of ROS scavenging. We also hypothesize that the demonstrated differences in the subcellular localization of the two Aux/IAA11 protein variants might indicate their regulation by alternative splicing. Our results suggest that Aux/IAA11 plays a specific role in chloroplast retrograde signaling, since it is not repressed by high (excess) light stress, exclusively among its phylogenetic clade.
Collapse
|
5
|
DeGennaro D, Urquidi Camacho RA, Zhang L, Shpak ED. Initiation of aboveground organ primordia depends on combined action of auxin, ERECTA family genes, and PINOID. PLANT PHYSIOLOGY 2022; 190:794-812. [PMID: 35703946 PMCID: PMC9434323 DOI: 10.1093/plphys/kiac288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Leaves and flowers are produced by the shoot apical meristem (SAM) at a certain distance from its center, a process that requires the hormone auxin. The amount of auxin and the pattern of its distribution in the initiation zone determine the size and spatial arrangement of organ primordia. Auxin gradients in the SAM are formed by PIN-FORMED (PIN) auxin efflux carriers whose polar localization in the plasma membrane depends on the protein kinase PINOID (PID). Previous work determined that ERECTA (ER) family genes (ERfs) control initiation of leaves. ERfs are plasma membrane receptors that enable cell-to-cell communication by sensing extracellular small proteins from the EPIDERMAL PATTERNING FACTOR/EPF-LIKE (EPF/EPFL) family. Here, we investigated whether ERfs regulate initiation of organs by altering auxin distribution or signaling in Arabidopsis (Arabidopsis thaliana). Genetic and pharmacological data suggested that ERfs do not regulate organogenesis through PINs while transcriptomics data showed that ERfs do not alter primary transcriptional responses to auxin. Our results indicated that in the absence of ERf signaling the peripheral zone cells inefficiently initiate leaves in response to auxin signals and that increased accumulation of auxin in the er erecta-like1 (erl1) erl2 SAM can partially rescue organ initiation defects. We propose that both auxin and ERfs are essential for leaf initiation and that they have common downstream targets. Genetic data also indicated that the role of PID in initiation of cotyledons and leaves cannot be attributed solely to regulation of PIN polarity and PID is likely to have other functions in addition to regulation of auxin distribution.
Collapse
Affiliation(s)
- Daniel DeGennaro
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | | | | | | |
Collapse
|
6
|
Abstract
Auxin signaling regulates growth and developmental processes in plants. The core of nuclear auxin signaling relies on just three components: TIR1/AFBs, Aux/IAAs, and ARFs. Each component is itself made up of several domains, all of which contribute to the regulation of auxin signaling. Studies of the structural aspects of these three core signaling components have deepened our understanding of auxin signaling dynamics and regulation. In addition to the structured domains of these components, intrinsically disordered regions within the proteins also impact auxin signaling outcomes. New research is beginning to uncover the role intrinsic disorder plays in auxin-regulated degradation and subcellular localization. Structured and intrinsically disordered domains affect auxin perception, protein degradation dynamics, and DNA binding. Taken together, subtle differences within the domains and motifs of each class of auxin signaling component affect signaling outcomes and specificity.
Collapse
Affiliation(s)
- Nicholas Morffy
- Department of Biology, Duke University, Durham, North Carolina 27708, USA
- Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, Missouri 63130, USA
| | - Lucia C Strader
- Department of Biology, Duke University, Durham, North Carolina 27708, USA
- Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, Missouri 63130, USA
- Center for Engineering Mechanobiology, Washington University, St. Louis, Missouri 63130, USA
| |
Collapse
|
7
|
Abstract
Auxin biology as a field has been at the forefront of advances in delineating the structures, dynamics, and control of plant growth networks. Advances have been enabled by combining the complementary fields of top-down, holistic systems biology and bottom-up, build-to-understand synthetic biology. Continued collaboration between these approaches will facilitate our understanding of and ability to engineer auxin's control of plant growth, development, and physiology. There is a need for the application of similar complementary approaches to improving equity and justice through analysis and redesign of the human systems in which this research is undertaken.
Collapse
Affiliation(s)
- R Clay Wright
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia 24061, USA
| | - Britney L Moss
- Department of Biology, Whitman College, Walla Walla, Washington 99362, USA
| | | |
Collapse
|
8
|
Liu Y, Cheng H, Cheng P, Wang C, Li J, Liu Y, Song A, Chen S, Chen F, Wang L, Jiang J. The BBX gene CmBBX22 negatively regulates drought stress tolerance in chrysanthemum. HORTICULTURE RESEARCH 2022; 9:uhac181. [PMID: 36338842 PMCID: PMC9630972 DOI: 10.1093/hr/uhac181] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 08/07/2022] [Indexed: 05/13/2023]
Abstract
BBX transcription factors play vital roles in plant growth, development, and stress responses. Although BBX proteins have been studied in great detail in the model plant Arabidopsis, their roles in crop plants such as chrysanthemum are still largely uninvestigated. Here, we cloned CmBBX22 and further determined the function of CmBBX22 in response to drought treatment. Subcellular localization and transactivation assay analyses revealed that CmBBX22 was localized in the nucleus and possessed transactivation activity. Overexpression of CmBBX22 in chrysanthemum was found to reduce plant drought tolerance, whereas expression of the chimeric repressor CmBBX22-SRDX was found to promote a higher drought tolerance than that shown by wild-type plants, indicating that CmBBX22 negatively regulates drought tolerance in chrysanthemum. Transcriptome analysis and physiological measurements indicated the potential involvement of the CmBBX22-mediated ABA response, stomatal conductance, and antioxidant responses in the negative regulation of drought tolerance in chrysanthemum. Based on the findings of this study, we were thus able to establish the mechanisms whereby the transcriptional activator CmBBX22 negatively regulates drought tolerance in chrysanthemum via the regulation of the abscisic acid response, stomatal conductance, and antioxidant responses.
Collapse
Affiliation(s)
| | | | - Peilei Cheng
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Chunmeng Wang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiayu Li
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Ye Liu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Aiping Song
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Sumei Chen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Fadi Chen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | | | | |
Collapse
|
9
|
Kacprzyk J, Burke R, Schwarze J, McCabe PF. Plant programmed cell death meets auxin signalling. FEBS J 2021; 289:1731-1745. [PMID: 34543510 DOI: 10.1111/febs.16210] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/26/2021] [Accepted: 09/17/2021] [Indexed: 11/28/2022]
Abstract
Both auxin signalling and programmed cell death (PCD) are essential components of a normally functioning plant. Auxin underpins plant growth and development, as well as regulating plant defences against environmental stresses. PCD, a genetically controlled pathway for selective elimination of redundant, damaged or infected cells, is also a key element of many developmental processes and stress response mechanisms in plants. An increasing body of evidence suggests that auxin signalling and PCD regulation are often connected. While generally auxin appears to suppress cell death, it has also been shown to promote PCD events, most likely via stimulation of ethylene biosynthesis. Intriguingly, certain cells undergoing PCD have also been suggested to control the distribution of auxin in plant tissues, by either releasing a burst of auxin or creating an anatomical barrier to auxin transport and distribution. These recent findings indicate novel roles of localized PCD events in the context of plant development such as control of root architecture, or tissue regeneration following injury, and suggest exciting possibilities for incorporation of this knowledge into crop improvement strategies.
Collapse
Affiliation(s)
- Joanna Kacprzyk
- School of Biology and Environmental Science, Science Centre, University College Dublin, Dublin, Ireland
| | - Rory Burke
- School of Biology and Environmental Science, Science Centre, University College Dublin, Dublin, Ireland
| | - Johanna Schwarze
- School of Biology and Environmental Science, Science Centre, University College Dublin, Dublin, Ireland
| | - Paul F McCabe
- School of Biology and Environmental Science, Science Centre, University College Dublin, Dublin, Ireland
| |
Collapse
|
10
|
Gala HP, Lanctot A, Jean-Baptiste K, Guiziou S, Chu JC, Zemke JE, George W, Queitsch C, Cuperus JT, Nemhauser JL. A single-cell view of the transcriptome during lateral root initiation in Arabidopsis thaliana. THE PLANT CELL 2021; 33:2197-2220. [PMID: 33822225 PMCID: PMC8364244 DOI: 10.1093/plcell/koab101] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/31/2021] [Indexed: 05/20/2023]
Abstract
Root architecture is a major determinant of plant fitness and is under constant modification in response to favorable and unfavorable environmental stimuli. Beyond impacts on the primary root, the environment can alter the position, spacing, density, and length of secondary or lateral roots. Lateral root development is among the best-studied examples of plant organogenesis, yet there are still many unanswered questions about its earliest steps. Among the challenges faced in capturing these first molecular events is the fact that this process occurs in a small number of cells with unpredictable timing. Single-cell sequencing methods afford the opportunity to isolate the specific transcriptional changes occurring in cells undergoing this fate transition. Using this approach, we successfully captured the transcriptomes of initiating lateral root primordia in Arabidopsis thaliana and discovered many upregulated genes associated with this process. We developed a method to selectively repress target gene transcription in the xylem pole pericycle cells where lateral roots originate and demonstrated that the expression of several of these targets is required for normal root development. We also discovered subpopulations of cells in the pericycle and endodermal cell files that respond to lateral root initiation, highlighting the coordination across cell files required for this fate transition.
Collapse
Affiliation(s)
- Hardik P. Gala
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Amy Lanctot
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Ken Jean-Baptiste
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Sarah Guiziou
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Jonah C. Chu
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Joseph E. Zemke
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Wesley George
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Josh T. Cuperus
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- Author for correspondence: (J.T.C.); (J.L.N.)
| | - Jennifer L. Nemhauser
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Author for correspondence: (J.T.C.); (J.L.N.)
| |
Collapse
|
11
|
Hormonal Regulation and Crosstalk of Auxin/Cytokinin Signaling Pathways in Potatoes In Vitro and in Relation to Vegetation or Tuberization Stages. Int J Mol Sci 2021; 22:ijms22158207. [PMID: 34360972 PMCID: PMC8347663 DOI: 10.3390/ijms22158207] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022] Open
Abstract
Auxins and cytokinins create versatile regulatory network controlling virtually all aspects of plant growth and development. These hormonal systems act in close contact, synergistically or antagonistically, determining plant phenotype, resistance and productivity. However, the current knowledge about molecular interactions of these systems is still scarce. Our study with potato plants aimed at deciphering potential interactions between auxin and cytokinin signaling pathways at the level of respective gene expression. Potato plants grown on sterile medium with 1.5% (vegetation) or 5% (tuberization) sucrose were treated for 1 h with auxin or cytokinin. Effects of these two hormones on expression profiles of genes belonging to main signaling pathways of auxin and cytokinin were quantified by RT-qPCR. As a result, several signaling genes were found to respond to auxin and/or cytokinin by up- or down-regulation. The observed effects were largely organ-specific and depended on sucrose content. Auxin strongly reduced cytokinin perception apparatus while reciprocal cytokinin effect was ambiguous and sucrose-dependent. In many cases, functional clustering of genes of the same family was observed. Promoters in some clusters are enriched with canonic hormone-response cis-elements supporting their direct sensitivity to hormones. Collectively, our data shed new light on the crosstalk between auxin- and cytokinin signaling pathways.
Collapse
|
12
|
Zhao C, Yaschenko A, Alonso JM, Stepanova AN. Leveraging synthetic biology approaches in plant hormone research. CURRENT OPINION IN PLANT BIOLOGY 2021; 60:101998. [PMID: 33476945 DOI: 10.1016/j.pbi.2020.101998] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/20/2020] [Accepted: 12/25/2020] [Indexed: 05/18/2023]
Abstract
The study of plant hormones is critical to understanding development, physiology and interactions of plants with their environment. Synthetic biology holds promise to provide a new perspective and shed fresh light on the molecular mechanisms of plant hormone action and propel the design of novel biotechnologies. With the recent adoption of synthetic biology in plant sciences, exciting first examples of successful tool development and their applications in the area of plant hormone research are emerging, paving the way for new cadres to enter this promising field of science.
Collapse
Affiliation(s)
- Chengsong Zhao
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Anna Yaschenko
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Jose M Alonso
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Anna N Stepanova
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA.
| |
Collapse
|
13
|
Ramos Báez R, Nemhauser JL. Expansion and innovation in auxin signaling: where do we grow from here? Development 2021; 148:148/5/dev187120. [PMID: 33712444 DOI: 10.1242/dev.187120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phytohormone auxin plays a role in almost all growth and developmental responses. The primary mechanism of auxin action involves the regulation of transcription via a core signaling pathway comprising proteins belonging to three classes: receptors, co-receptor/co-repressors and transcription factors. Recent studies have revealed that auxin signaling can be traced back at least as far as the transition to land. Moreover, studies in flowering plants have highlighted how expansion of the gene families encoding auxin components is tied to functional diversification. As we review here, these studies paint a picture of auxin signaling evolution as a driver of innovation.
Collapse
Affiliation(s)
- Román Ramos Báez
- University of Washington, Department of Biology, Seattle, WA 98105-1800, USA
| | | |
Collapse
|
14
|
Architecture of DNA elements mediating ARF transcription factor binding and auxin-responsive gene expression in Arabidopsis. Proc Natl Acad Sci U S A 2020; 117:24557-24566. [PMID: 32929017 PMCID: PMC7533888 DOI: 10.1073/pnas.2009554117] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The hormone auxin controls many aspects of the plant life cycle by regulating the expression of thousands of genes. The transcriptional output of the nuclear auxin signaling pathway is determined by the activity of AUXIN RESPONSE transcription FACTORs (ARFs), through their binding to cis-regulatory elements in auxin-responsive genes. Crystal structures, in vitro, and heterologous studies have fueled a model in which ARF dimers bind with high affinity to distinctly spaced repeats of canonical AuxRE motifs. However, the relevance of this "caliper" model, and the mechanisms underlying the binding affinities in vivo, have remained elusive. Here we biochemically and functionally interrogate modes of ARF-DNA interaction. We show that a single additional hydrogen bond in Arabidopsis ARF1 confers high-affinity binding to individual DNA sites. We demonstrate the importance of AuxRE cooperativity within repeats in the Arabidopsis TMO5 and IAA11 promoters in vivo. Meta-analysis of transcriptomes further reveals strong genome-wide association of auxin response with both inverted (IR) and direct (DR) AuxRE repeats, which we experimentally validated. The association of these elements with auxin-induced up-regulation (DR and IR) or down-regulation (IR) was correlated with differential binding affinities of A-class and B-class ARFs, respectively, suggesting a mechanistic basis for the distinct activity of these repeats. Our results support the relevance of high-affinity binding of ARF transcription factors to uniquely spaced DNA elements in vivo, and suggest that differential binding affinities of ARF subfamilies underlie diversity in cis-element function.
Collapse
|
15
|
Israeli A, Reed JW, Ori N. Genetic dissection of the auxin response network. NATURE PLANTS 2020; 6:1082-1090. [PMID: 32807951 DOI: 10.1038/s41477-020-0739-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/06/2020] [Indexed: 05/24/2023]
Abstract
The expansion of gene families during evolution, which can generate functional overlap or specialization among their members, is a characteristic feature of signalling pathways in complex organisms. For example, families of transcriptional activators and repressors mediate responses to the plant hormone auxin. Although these regulators were identified more than 20 years ago, their overlapping functions and compensating negative feedbacks have hampered their functional analyses. Studies using loss-of-function approaches in basal land plants and gain-of-function approaches in angiosperms have in part overcome these issues but have still left an incomplete understanding. Here, we propose that renewed emphasis on genetic analysis of multiple mutants and species will shed light on the role of gene families in auxin response. Combining loss-of-function mutations in auxin-response activators and repressors can unravel complex outputs enabled by expanded gene families, such as fine-tuned developmental outcomes and robustness. Similar approaches and concepts may help to analyse other regulatory pathways whose components are also encoded by large gene families.
Collapse
Affiliation(s)
- Alon Israeli
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot, Israel
| | - Jason W Reed
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Naomi Ori
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot, Israel.
| |
Collapse
|
16
|
Ramos Báez R, Buckley Y, Yu H, Chen Z, Gallavotti A, Nemhauser JL, Moss BL. A Synthetic Approach Allows Rapid Characterization of the Maize Nuclear Auxin Response Circuit. PLANT PHYSIOLOGY 2020; 182:1713-1722. [PMID: 32123041 PMCID: PMC7140906 DOI: 10.1104/pp.19.01475] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/22/2020] [Indexed: 05/20/2023]
Abstract
Auxin plays a key role across all land plants in growth and developmental processes. Although auxin signaling function has diverged and expanded, differences in the molecular functions of signaling components have largely been characterized in Arabidopsis (Arabidopsis thaliana). Here, we used the nuclear Auxin Response Circuit recapitulated in yeast (Saccharomyces cerevisiae) system to functionally annotate maize (Zea mays) auxin signaling components, focusing on genes expressed during the development of ear and tassel inflorescences. All 16 maize auxin/indole-3-acetic acid repressor proteins were degraded in response to auxin with rates that depended on both receptor and repressor identities. When fused to the maize TOPLESS homolog RAMOSA1 ENHANCER LOCUS2, maize auxin/indole-3-acetic acids were able to repress AUXIN RESPONSE FACTOR transcriptional activity. A complete auxin response circuit comprising all maize components, including the ZmAFB2/3 b1 maize AUXIN SIGNALING F-BOX (AFB) receptor, was fully functional. The ZmAFB2/3 b1 auxin receptor was more sensitive to hormone than AtAFB2 and allowed for rapid circuit activation upon auxin addition. These results validate the conserved role of predicted auxin response genes in maize as well as provide evidence that a synthetic approach can facilitate broader comparative studies across the wide range of species with sequenced genomes.
Collapse
Affiliation(s)
- Román Ramos Báez
- University of Washington, Department of Biology, Seattle, Washington 98105
| | - Yuli Buckley
- Whitman College, Department of Biology, Walla Walla, Washington 99362
| | - Han Yu
- Whitman College, Department of Biology, Walla Walla, Washington 99362
| | - Zongliang Chen
- Waksman Institute of Microbiology, Rutgers University, Piscataway, New Jersey 08854-8020
| | - Andrea Gallavotti
- Waksman Institute of Microbiology, Rutgers University, Piscataway, New Jersey 08854-8020
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey 08901
| | | | - Britney L Moss
- Whitman College, Department of Biology, Walla Walla, Washington 99362
| |
Collapse
|