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Nowak K, Wójcikowska B, Gajecka M, Elżbieciak A, Morończyk J, Wójcik AM, Żemła P, Citerne S, Kiwior-Wesołowska A, Zbieszczyk J, Gaj MD. The improvement of the in vitro plant regeneration in barley with the epigenetic modifier of histone acetylation, trichostatin A. J Appl Genet 2024; 65:13-30. [PMID: 37962803 PMCID: PMC10789698 DOI: 10.1007/s13353-023-00800-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/16/2023] [Accepted: 10/25/2023] [Indexed: 11/15/2023]
Abstract
Genotype-limited plant regeneration is one of the main obstacles to the broader use of genetic transformation in barley breeding. Thus, developing new approaches that might improve responses of in vitro recalcitrant genotypes remains at the center of barley biotechnology. Here, we analyzed different barley genotypes, including "Golden Promise," a genotype commonly used in the genetic transformation, and four malting barley cultivars of poor regenerative potential. The expression of hormone-related transcription factor (TF) genes with documented roles in plant regeneration was analyzed in genotypes with various plant-regenerating capacities. The results indicated differential expression of auxin-related TF genes between the barley genotypes in both the explants and the derived cultures. In support of the role of auxin in barley regeneration, distinct differences in the accumulation of free and oxidized auxin were observed in explants and explant-derived callus cultures of barley genotypes. Following the assumption that modifying gene expression might improve plant regeneration in barley, we treated the barley explants with trichostatin A (TSA), which affects histone acetylation. The effects of TSA were genotype-dependent as TSA treatment improved plant regeneration in two barley cultivars. TSA-induced changes in plant regeneration were associated with the increased expression of auxin biosynthesis-involved TFs. The study demonstrated that explant treatment with chromatin modifiers such as TSA might provide a new and effective epigenetic approach to improving plant regeneration in recalcitrant barley genotypes.
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Affiliation(s)
- Katarzyna Nowak
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland.
| | - Barbara Wójcikowska
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Monika Gajecka
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Anna Elżbieciak
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Joanna Morończyk
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Anna M Wójcik
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Przemysław Żemła
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
- Toxicology Research Group, Łukasiewicz Research Network, Institute of Industrial Organic Chemistry Branch Pszczyna, Doświadczalna 27, 43-200, Pszczyna, Poland
| | - Sylvie Citerne
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Agnieszka Kiwior-Wesołowska
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Justyna Zbieszczyk
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
| | - Małgorzata D Gaj
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, 40-007, Katowice, Poland
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Wójcikowska B, Belaidi S, Robert HS. Game of thrones among AUXIN RESPONSE FACTORs-over 30 years of MONOPTEROS research. J Exp Bot 2023; 74:6904-6921. [PMID: 37450945 PMCID: PMC10690734 DOI: 10.1093/jxb/erad272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
For many years, research has been carried out with the aim of understanding the mechanism of auxin action, its biosynthesis, catabolism, perception, and transport. One central interest is the auxin-dependent gene expression regulation mechanism involving AUXIN RESPONSE FACTOR (ARF) transcription factors and their repressors, the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins. Numerous studies have been focused on MONOPTEROS (MP)/ARF5, an activator of auxin-dependent gene expression with a crucial impact on plant development. This review summarizes over 30 years of research on MP/ARF5. We indicate the available analytical tools to study MP/ARF5 and point out the known mechanism of MP/ARF5-dependent regulation of gene expression during various developmental processes, namely embryogenesis, leaf formation, vascularization, and shoot and root meristem formation. However, many questions remain about the auxin dose-dependent regulation of gene transcription by MP/ARF5 and its isoforms in plant cells, the composition of the MP/ARF5 protein complex, and, finally, all the genes under its direct control. In addition, information on post-translational modifications of MP/ARF5 protein is marginal, and knowledge about their consequences on MP/ARF5 function is limited. Moreover, the epigenetic factors and other regulators that act upstream of MP/ARF5 are poorly understood. Their identification will be a challenge in the coming years.
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Affiliation(s)
- Barbara Wójcikowska
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- Institute of Biology, Biotechnology, and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Samia Belaidi
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Hélène S Robert
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, Czech Republic
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Wójcikowska B, Wójcik AM, Gaj MD. Epigenetic Regulation of Auxin-Induced Somatic Embryogenesis in Plants. Int J Mol Sci 2020; 21:ijms21072307. [PMID: 32225116 PMCID: PMC7177879 DOI: 10.3390/ijms21072307] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 03/17/2020] [Accepted: 03/24/2020] [Indexed: 12/22/2022] Open
Abstract
Somatic embryogenesis (SE) that is induced in plant explants in response to auxin treatment is closely associated with an extensive genetic reprogramming of the cell transcriptome. The significant modulation of the gene transcription profiles during SE induction results from the epigenetic factors that fine-tune the gene expression towards embryogenic development. Among these factors, microRNA molecules (miRNAs) contribute to the post-transcriptional regulation of gene expression. In the past few years, several miRNAs that regulate the SE-involved transcription factors (TFs) have been identified, and most of them were involved in the auxin-related processes, including auxin metabolism and signaling. In addition to miRNAs, chemical modifications of DNA and chromatin, in particular the methylation of DNA and histones and histone acetylation, have been shown to shape the SE transcriptomes. In response to auxin, these epigenetic modifications regulate the chromatin structure, and hence essentially contribute to the control of gene expression during SE induction. In this paper, we describe the current state of knowledge with regard to the SE epigenome. The complex interactions within and between the epigenetic factors, the key SE TFs that have been revealed, and the relationships between the SE epigenome and auxin-related processes such as auxin perception, metabolism, and signaling are highlighted.
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Wójcik AM, Wójcikowska B, Gaj MD. Current Perspectives on the Auxin-Mediated Genetic Network that Controls the Induction of Somatic Embryogenesis in Plants. Int J Mol Sci 2020; 21:E1333. [PMID: 32079138 PMCID: PMC7072907 DOI: 10.3390/ijms21041333] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 12/22/2022] Open
Abstract
Auxin contributes to almost every aspect of plant development and metabolism as well as the transport and signalling of auxin-shaped plant growth and morphogenesis in response to endo- and exogenous signals including stress conditions. Consistently with the common belief that auxin is a central trigger of developmental changes in plants, the auxin treatment of explants was reported to be an indispensable inducer of somatic embryogenesis (SE) in a large number of plant species. Treating in vitro-cultured tissue with auxins (primarily 2,4-dichlorophenoxyacetic acid, which is a synthetic auxin-like plant growth regulator) results in the extensive reprogramming of the somatic cell transcriptome, which involves the modulation of numerous SE-associated transcription factor genes (TFs). A number of SE-modulated TFs that control auxin metabolism and signalling have been identified, and conversely, the regulators of the auxin-signalling pathway seem to control the SE-involved TFs. In turn, the different expression of the genes encoding the core components of the auxin-signalling pathway, the AUXIN/INDOLE-3-ACETIC ACIDs (Aux/IAAs) and AUXIN RESPONSE FACTORs (ARFs), was demonstrated to accompany SE induction. Thus, the extensive crosstalk between the hormones, in particular, auxin and the TFs, was revealed to play a central role in the SE-regulatory network. Accordingly, LEAFY COTYLEDON (LEC1 and LEC2), BABY BOOM (BBM), AGAMOUS-LIKE15 (AGL15) and WUSCHEL (WUS) were found to constitute the central part of the complex regulatory network that directs the somatic plant cell towards embryogenic development in response to auxin. The revealing picture shows a high degree of complexity of the regulatory relationships between the TFs of the SE-regulatory network, which involve direct and indirect interactions and regulatory feedback loops. This review examines the recent advances in studies on the auxin-controlled genetic network, which is involved in the mechanism of SE induction and focuses on the complex regulatory relationships between the down- and up-stream targets of the SE-regulatory TFs. In particular, the outcomes from investigations on Arabidopsis, which became a model plant in research on genetic control of SE, are presented.
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Wójcikowska B, Botor M, Morończyk J, Wójcik AM, Nodzyński T, Karcz J, Gaj MD. Trichostatin A Triggers an Embryogenic Transition in Arabidopsis Explants via an Auxin-Related Pathway. Front Plant Sci 2018; 9:1353. [PMID: 30271420 PMCID: PMC6146766 DOI: 10.3389/fpls.2018.01353] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 08/28/2018] [Indexed: 05/23/2023]
Abstract
Auxin is an important regulator of plant ontogenies including embryo development and the exogenous application of this phytohormone has been found to be necessary for the induction of the embryogenic response in plant explants that have been cultured in vitro. However, in the present study, we show that treatment of Arabidopsis explants with trichostatin A (TSA), which is a chemical inhibitor of histone deacetylases, induces somatic embryogenesis (SE) without the exogenous application of auxin. We found that the TSA-treated explants generated somatic embryos that developed efficiently on the adaxial side of the cotyledons, which are the parts of an explant that are involved in auxin-induced SE. A substantial reduction in the activity of histone deacetylase (HDAC) was observed in the TSA-treated explants, thus confirming a histone acetylation-related mechanism of the TSA-promoted embryogenic response. Unexpectedly, the embryogenic effect of TSA was lower on the auxin-supplemented media and this finding further suggests an auxin-related mechanism of TSA-induced SE. Congruently, we found a significantly increased content of indolic compounds, which is indicative of IAA and an enhanced DR5::GUS signal in the TSA-treated explants. In line with these results, two of the YUCCA genes (YUC1 and YUC10), which are involved in auxin biosynthesis, were found to be distinctly up-regulated during TSA-induced SE and their expression was colocalised with the explant sites that are involved in SE. Beside auxin, ROS were extensively accumulated in response to TSA, thereby indicating that a stress-response is involved in TSA-triggered SE. Relevantly, we showed that the genes encoding the transcription factors (TFs) that have a regulatory function in auxin biosynthesis including LEC1, LEC2, BBM, and stress responses (MYB118) were highly up-regulated in the TSA-treated explants. Collectively, the results provide several pieces of evidence about the similarities between the molecular pathways of SE induction that are triggered by TSA and 2,4-D that involve the activation of the auxin-responsive TF genes that have a regulatory function in auxin biosynthesis and stress responses. The study suggests the involvement of histone acetylation in the auxin-mediated release of the embryogenic program of development in the somatic cells of Arabidopsis.
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Affiliation(s)
| | - Malwina Botor
- Department of Molecular Biology and Genetics, Medical University of SilesiaKatowice, Poland
| | - Joanna Morończyk
- Department of Genetics, University of Silesia in KatowiceKatowice, Poland
| | - Anna Maria Wójcik
- Department of Genetics, University of Silesia in KatowiceKatowice, Poland
| | - Tomasz Nodzyński
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU – Central European Institute of Technology, Masaryk UniversityBrno, Czechia
| | - Jagna Karcz
- Scanning Electron Microscopy Laboratory, University of Silesia in KatowiceKatowice, Poland
| | - Małgorzata D. Gaj
- Department of Genetics, University of Silesia in KatowiceKatowice, Poland
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Robert HS, Park C, Gutièrrez CL, Wójcikowska B, Pěnčík A, Novák O, Chen J, Grunewald W, Dresselhaus T, Friml J, Laux T. Maternal auxin supply contributes to early embryo patterning in Arabidopsis. Nat Plants 2018; 4:548-553. [PMID: 30013211 PMCID: PMC6076996 DOI: 10.1038/s41477-018-0204-z] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 06/15/2018] [Indexed: 05/18/2023]
Abstract
The angiosperm seed is composed of three genetically distinct tissues: the diploid embryo that originates from the fertilized egg cell, the triploid endosperm that is produced from the fertilized central cell, and the maternal sporophytic integuments that develop into the seed coat1. At the onset of embryo development in Arabidopsis thaliana, the zygote divides asymmetrically, producing a small apical embryonic cell and a larger basal cell that connects the embryo to the maternal tissue2. The coordinated and synchronous development of the embryo and the surrounding integuments, and the alignment of their growth axes, suggest communication between maternal tissues and the embryo. In contrast to animals, however, where a network of maternal factors that direct embryo patterning have been identified3,4, only a few maternal mutations have been described to affect embryo development in plants5-7. Early embryo patterning in Arabidopsis requires accumulation of the phytohormone auxin in the apical cell by directed transport from the suspensor8-10. However, the origin of this auxin has remained obscure. Here we investigate the source of auxin for early embryogenesis and provide evidence that the mother plant coordinates seed development by supplying auxin to the early embryo from the integuments of the ovule. We show that auxin response increases in ovules after fertilization, due to upregulated auxin biosynthesis in the integuments, and this maternally produced auxin is required for correct embryo development.
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Affiliation(s)
- Hélène S Robert
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium.
| | - Chulmin Park
- BIOSS Centre for Biological Signaling Studies, Faculty of Biology, Albert-Ludwigs-Universitaet Freiburg, Freiburg, Germany
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
| | - Carla Loreto Gutièrrez
- BIOSS Centre for Biological Signaling Studies, Faculty of Biology, Albert-Ludwigs-Universitaet Freiburg, Freiburg, Germany
| | - Barbara Wójcikowska
- Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia, Katowice, Poland
| | - Aleš Pěnčík
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science of Palacký University and Institute of Experimental Botany CAS, Olomouc, Czech Republic
| | - Ondřej Novák
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science of Palacký University and Institute of Experimental Botany CAS, Olomouc, Czech Republic
| | - Junyi Chen
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany
| | - Wim Grunewald
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany
| | - Jiří Friml
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
| | - Thomas Laux
- BIOSS Centre for Biological Signaling Studies, Faculty of Biology, Albert-Ludwigs-Universitaet Freiburg, Freiburg, Germany.
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Wójcikowska B, Gaj MD. Expression profiling of AUXIN RESPONSE FACTOR genes during somatic embryogenesis induction in Arabidopsis. Plant Cell Rep 2017; 36:843-858. [PMID: 28255787 PMCID: PMC5486788 DOI: 10.1007/s00299-017-2114-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 02/01/2017] [Indexed: 05/18/2023]
Abstract
Extensive modulation of numerous ARF transcripts in the embryogenic culture of Arabidopsis indicates a substantial role of auxin signaling in the mechanism of somatic embryogenesis induction. Somatic embryogenesis (SE) is induced by auxin in plants and auxin signaling is considered to play a key role in the molecular mechanism that controls the embryogenic transition of plant somatic cells. Accordingly, the expression of AUXIN RESPONSE FACTOR (ARF) genes in embryogenic culture of Arabidopsis was analyzed. The study revealed that 14 of the 22 ARFs were transcribed during SE in Arabidopsis. RT-qPCR analysis indicated that the expression of six ARFs (ARF5, ARF6, ARF8, ARF10, ARF16, and ARF17) was significantly up-regulated, whereas five other genes (ARF1, ARF2, ARF3, ARF11, and ARF18) were substantially down-regulated in the SE-induced explants. The activity of ARFs during SE was also monitored with GFP reporter lines and the ARFs that were expressed in areas of the explants engaged in SE induction were detected. A functional test of ARFs transcribed during SE was performed and the embryogenic potential of the arf mutants and overexpressor lines was evaluated. ARFs with a significantly modulated expression during SE coupled with an impaired embryogenic response of the relevant mutant and/or overexpressor line, including ARF1, ARF2, ARF3, ARF5, ARF6, ARF8, and ARF11 were indicated as possibly being involved in SE induction. The study provides evidence that embryogenic induction strongly depends on ARFs, which are key regulators of the auxin signaling. Some clues on the possible functions of the candidate ARFs, especially ARF5, in the mechanism of embryogenic transition are discussed. The results provide guidelines for further research on the auxin-related functional genomics of SE and the developmental plasticity of somatic cells.
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Affiliation(s)
- Barbara Wójcikowska
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032, Katowice, Poland
| | - Małgorzata D Gaj
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032, Katowice, Poland.
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Nowak K, Wójcikowska B, Gaj MD. ERF022 impacts the induction of somatic embryogenesis in Arabidopsis through the ethylene-related pathway. Planta 2015; 241:967-85. [PMID: 25534944 PMCID: PMC4361773 DOI: 10.1007/s00425-014-2225-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/04/2014] [Indexed: 05/04/2023]
Abstract
The ERF022 gene was found to affect embryogenic transition in somatic cells in Arabidopsis via the ethylene-related pathway. The study provides evidence that ERF022 - LEC2 interaction is involved in the auxin-ethylene crosstalk that operates in somatic embryogenesis induction. The ERF022 gene of the ERF family was previously identified among the transcription factor genes that were differentially expressed in an embryogenic culture of Arabidopsis. A strong inhibition of the gene was found to be associated with the induction of somatic embryogenesis (SE) and an erf022 mutant was indicated to display a substantially impaired capacity for SE. Therefore, the molecular function of ERF022 in the induction of SE was studied in the present work. A phenotype of an erf022 mutant was indicated as being related to an increased content of ethylene. The results further suggest that the ERF022 controls the genes that are involved in both the biosynthesis (ACS7) and signalling (ERF1, ETR1) of ethylene and indicate that the ERF022 is a new regulatory element in ethylene-related responses that negatively control the ethylene content and perception. It is proposed that the negative impact of ethylene on the induction of SE may result from a modulation of the auxin-related genes that control the embryogenic transition in somatic cells. Among them, the LEC2, which is a key regulator of the induction of SE through the stimulation of auxin synthesis, was possibly related to ERF022. The results of the study provide new hormone-related clues to define the genetic network that governs SE. A putative model of the regulatory pathway is proposed that is involved in the induction of SE in which the auxin-ethylene interactions are controlled by ERF022 and LEC2 and their targets.
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Affiliation(s)
- Katarzyna Nowak
- Department of Genetics, University of Silesia, Jagiellonska 28, 40-032 Katowice, Poland
| | - Barbara Wójcikowska
- Department of Genetics, University of Silesia, Jagiellonska 28, 40-032 Katowice, Poland
| | - Małgorzata D. Gaj
- Department of Genetics, University of Silesia, Jagiellonska 28, 40-032 Katowice, Poland
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Nowak K, Wójcikowska B, Gaj MD. ERF022 impacts the induction of somatic embryogenesis in Arabidopsis through the ethylene-related pathway. Planta 2015. [PMID: 25534944 DOI: 10.1007/s00425-014-22259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The ERF022 gene was found to affect embryogenic transition in somatic cells in Arabidopsis via the ethylene-related pathway. The study provides evidence that ERF022 - LEC2 interaction is involved in the auxin-ethylene crosstalk that operates in somatic embryogenesis induction. The ERF022 gene of the ERF family was previously identified among the transcription factor genes that were differentially expressed in an embryogenic culture of Arabidopsis. A strong inhibition of the gene was found to be associated with the induction of somatic embryogenesis (SE) and an erf022 mutant was indicated to display a substantially impaired capacity for SE. Therefore, the molecular function of ERF022 in the induction of SE was studied in the present work. A phenotype of an erf022 mutant was indicated as being related to an increased content of ethylene. The results further suggest that the ERF022 controls the genes that are involved in both the biosynthesis (ACS7) and signalling (ERF1, ETR1) of ethylene and indicate that the ERF022 is a new regulatory element in ethylene-related responses that negatively control the ethylene content and perception. It is proposed that the negative impact of ethylene on the induction of SE may result from a modulation of the auxin-related genes that control the embryogenic transition in somatic cells. Among them, the LEC2, which is a key regulator of the induction of SE through the stimulation of auxin synthesis, was possibly related to ERF022. The results of the study provide new hormone-related clues to define the genetic network that governs SE. A putative model of the regulatory pathway is proposed that is involved in the induction of SE in which the auxin-ethylene interactions are controlled by ERF022 and LEC2 and their targets.
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Affiliation(s)
- Katarzyna Nowak
- Department of Genetics, University of Silesia, Jagiellonska 28, 40-032, Katowice, Poland
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Wójcikowska B, Jaskóła K, Gąsiorek P, Meus M, Nowak K, Gaj MD. LEAFY COTYLEDON2 (LEC2) promotes embryogenic induction in somatic tissues of Arabidopsis, via YUCCA-mediated auxin biosynthesis. Planta 2013. [PMID: 23722561 DOI: 10.1007/s00425-013-18922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The LEAFY COTYLEDON2 (LEC2) transcription factor with a plant-specific B3 domain plays a central role in zygotic and somatic embryogenesis (SE). LEC2 overexpression induced in planta leads to spontaneous somatic embryo formation, but impairs the embryogenic response of explants cultured in vitro under auxin treatment. The auxin-related functions of LEC2 appear during SE induction, and the aim of the present study was to gain further insights into this phenomenon. To this end, the effect of LEC2 overexpression on the morphogenic responses of Arabidopsis explants cultured in vitro under different auxin treatments was evaluated. The expression profiles of the auxin biosynthesis genes were analysed in embryogenic cultures with respect to LEC2 activity. The results showed that LEC2 overexpression severely modifies the requirement of cultured explants for an exogenous auxin concentration at a level that is effective in SE induction and suggested an increase in the auxin content in 35S::LEC2-GR transgenic explants. The assumption of an LEC2 promoted increase in endogenous auxin in cultured explants was further supported by the expression profiling of the genes involved in auxin biosynthesis. The analysis indicated that YUCCAs and TAA1, working in the IPA-YUC auxin biosynthesis pathway, are associated with SE induction, and that the expression of three YUCCA genes (YUC1, YUC4 and YUC10) is associated with LEC2 activity. The results also suggest that the IAOx-mediated auxin biosynthesis pathway involving ATR1/MYB34 and CYP79B2 does not seem to be involved in SE induction. We conclude that de novo auxin production via the tryptophan-dependent IPA-YUC auxin biosynthesis pathway is implicated in SE induction, and that LEC2 plays a key role in this mechanism.
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Affiliation(s)
- Barbara Wójcikowska
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032, Katowice, Poland
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Wójcikowska B, Jaskóła K, Gąsiorek P, Meus M, Nowak K, Gaj MD. LEAFY COTYLEDON2 (LEC2) promotes embryogenic induction in somatic tissues of Arabidopsis, via YUCCA-mediated auxin biosynthesis. Planta 2013; 238:425-40. [PMID: 23722561 PMCID: PMC3751287 DOI: 10.1007/s00425-013-1892-2] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/24/2013] [Indexed: 05/18/2023]
Abstract
The LEAFY COTYLEDON2 (LEC2) transcription factor with a plant-specific B3 domain plays a central role in zygotic and somatic embryogenesis (SE). LEC2 overexpression induced in planta leads to spontaneous somatic embryo formation, but impairs the embryogenic response of explants cultured in vitro under auxin treatment. The auxin-related functions of LEC2 appear during SE induction, and the aim of the present study was to gain further insights into this phenomenon. To this end, the effect of LEC2 overexpression on the morphogenic responses of Arabidopsis explants cultured in vitro under different auxin treatments was evaluated. The expression profiles of the auxin biosynthesis genes were analysed in embryogenic cultures with respect to LEC2 activity. The results showed that LEC2 overexpression severely modifies the requirement of cultured explants for an exogenous auxin concentration at a level that is effective in SE induction and suggested an increase in the auxin content in 35S::LEC2-GR transgenic explants. The assumption of an LEC2 promoted increase in endogenous auxin in cultured explants was further supported by the expression profiling of the genes involved in auxin biosynthesis. The analysis indicated that YUCCAs and TAA1, working in the IPA-YUC auxin biosynthesis pathway, are associated with SE induction, and that the expression of three YUCCA genes (YUC1, YUC4 and YUC10) is associated with LEC2 activity. The results also suggest that the IAOx-mediated auxin biosynthesis pathway involving ATR1/MYB34 and CYP79B2 does not seem to be involved in SE induction. We conclude that de novo auxin production via the tryptophan-dependent IPA-YUC auxin biosynthesis pathway is implicated in SE induction, and that LEC2 plays a key role in this mechanism.
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Affiliation(s)
- Barbara Wójcikowska
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Karolina Jaskóła
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Przemysław Gąsiorek
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Magdalena Meus
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Katarzyna Nowak
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Małgorzata D. Gaj
- Department of Genetics, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
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