101
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Urano D, Chen JG, Botella JR, Jones AM. Heterotrimeric G protein signalling in the plant kingdom. Open Biol 2013; 3:120186. [PMID: 23536550 PMCID: PMC3718340 DOI: 10.1098/rsob.120186] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/05/2013] [Indexed: 12/18/2022] Open
Abstract
In animals, heterotrimeric G proteins, comprising α-, β-and γ-subunits, perceive extracellular stimuli through cell surface receptors, and transmit signals to ion channels, enzymes and other effector proteins to affect numerous cellular behaviours. In plants, G proteins have structural similarities to the corresponding molecules in animals but transmit signals by atypical mechanisms and effector proteins to control growth, cell proliferation, defence, stomate movements, channel regulation, sugar sensing and some hormonal responses. In this review, we summarize the current knowledge on the molecular regulation of plant G proteins, their effectors and the physiological functions studied mainly in two model organisms: Arabidopsis thaliana and rice (Oryza sativa). We also look at recent progress on structural analyses, systems biology and evolutionary studies.
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Affiliation(s)
- Daisuke Urano
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jin-Gui Chen
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - José Ramón Botella
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alan M. Jones
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
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102
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Kumimoto RW, Siriwardana CL, Gayler KK, Risinger JR, Siefers N, Holt BF. NUCLEAR FACTOR Y transcription factors have both opposing and additive roles in ABA-mediated seed germination. PLoS One 2013; 8:e59481. [PMID: 23527203 PMCID: PMC3602376 DOI: 10.1371/journal.pone.0059481] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 02/14/2013] [Indexed: 11/18/2022] Open
Abstract
In the model organism Arabidopsis thaliana the heterotrimeric transcription factor NUCLEAR FACTOR Y (NF-Y) has been shown to play multiple roles in facilitating plant growth and development. Although NF-Y itself represents a multi-protein transcriptional complex, recent studies have shown important interactions with other transcription factors, especially those in the bZIP family. Here we add to the growing evidence that NF-Y and bZIP form common complexes to affect many processes. We carried out transcriptional profiling on nf-yc mutants and through subsequent analyses found an enrichment of bZIP binding sites in the promoter elements of misregulated genes. Using NF-Y as bait, yeast two hybrid assays yielded interactions with bZIP proteins that are known to control ABA signaling. Accordingly, we find that plants mutant for several NF-Y subunits show characteristic phenotypes associated with the disruption of ABA signaling. While previous reports have shown additive roles for NF-YC family members in photoperiodic flowering, we found that they can have opposing roles in ABA signaling. Collectively, these results demonstrated the importance and complexity of NF-Y in the integration of environmental and hormone signals.
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Affiliation(s)
- Roderick W. Kumimoto
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Chamindika L. Siriwardana
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Krystal K. Gayler
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Jan R. Risinger
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Nicholas Siefers
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Ben F. Holt
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America
- * E-mail:
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103
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Thung L, Chakravorty D, Trusov Y, Jones AM, Botella JR. Signaling specificity provided by the Arabidopsis thaliana heterotrimeric G-protein γ subunits AGG1 and AGG2 is partially but not exclusively provided through transcriptional regulation. PLoS One 2013; 8:e58503. [PMID: 23520518 PMCID: PMC3592790 DOI: 10.1371/journal.pone.0058503] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 02/05/2013] [Indexed: 11/18/2022] Open
Abstract
The heterotrimeric G-protein complex in Arabidopsis thaliana consists of one α, one ß and three γ subunits. While two of the γ subunits, AGG1 and AGG2 have been shown to provide functional selectivity to the Gßγ dimer in Arabidopsis, it is unclear if such selectivity is embedded in their molecular structures or conferred by the different expression patterns observed in both subunits. In order to study the molecular basis for such selectivity we tested genetic complementation of AGG1- and AGG2 driven by the respectively swapped gene promoters. When expressed in the same tissues as AGG1, AGG2 rescues some agg1 mutant phenotypes such as the hypersensitivity to Fusarium oxysporum and D-mannitol as well as the altered levels of lateral roots, but does not rescue the early flowering phenotype. Similarly, AGG1 when expressed in the same tissues as AGG2 rescues the osmotic stress and lateral-root phenotypes observed in agg2 mutants but failed to rescue the heat-stress induction of flowering. The fact that AGG1 and AGG2 are functionally interchangeable in some pathways implies that, at least for those pathways, signaling specificity resides in the distinctive spatiotemporal expression patterns exhibited by each γ subunit. On the other hand, the lack of complementation for some phenotypes indicates that there are pathways in which signaling specificity is provided by differences in the primary AGG1 and AGG2 amino acid sequences.
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Affiliation(s)
- Leena Thung
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - David Chakravorty
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Yuri Trusov
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Alan M. Jones
- Departments of Biology and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - José Ramón Botella
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
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104
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Laloum T, De Mita S, Gamas P, Baudin M, Niebel A. CCAAT-box binding transcription factors in plants: Y so many? TRENDS IN PLANT SCIENCE 2013; 18:157-66. [PMID: 22939172 DOI: 10.1016/j.tplants.2012.07.004] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/25/2012] [Accepted: 07/28/2012] [Indexed: 05/20/2023]
Abstract
Transcription factors belonging to the CCAAT-box binding factor family (also known as the Nuclear Factor Y) are present in all higher eukaryotes. Studies in plants have revealed that each subunit of this heterotrimeric transcription factor is encoded by a gene belonging to a multigene family allowing a considerable modularity. In this review, we focus on recent findings concerning the expression patterns and potential functions of different members of these NF-Y protein families using a phylogenetic approach. During the course of evolution plant CCAAT-box binding factors seem to have diversified into at least two main groups. The first group has more general expression patterns and/or functions whereas the second group has acquired more specific expression patterns and/or functions and could play key roles in specific pathways.
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Affiliation(s)
- Tom Laloum
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326 Castanet-Tolosan, France
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105
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He JM, Ma XG, Zhang Y, Sun TF, Xu FF, Chen YP, Liu X, Yue M. Role and interrelationship of Gα protein, hydrogen peroxide, and nitric oxide in ultraviolet B-induced stomatal closure in Arabidopsis leaves. PLANT PHYSIOLOGY 2013; 161:1570-83. [PMID: 23341360 PMCID: PMC3585617 DOI: 10.1104/pp.112.211623] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 01/18/2013] [Indexed: 05/18/2023]
Abstract
Heterotrimeric G proteins have been shown to transmit ultraviolet B (UV-B) signals in mammalian cells, but whether they also transmit UV-B signals in plant cells is not clear. In this paper, we report that 0.5 W m(-2) UV-B induces stomatal closure in Arabidopsis (Arabidopsis thaliana) by eliciting a cascade of intracellular signaling events including Gα protein, hydrogen peroxide (H2O2), and nitric oxide (NO). UV-B triggered a significant increase in H2O2 or NO levels associated with stomatal closure in the wild type, but these effects were abolished in the single and double mutants of AtrbohD and AtrbohF or in the Nia1 mutants, respectively. Furthermore, we found that UV-B-mediated H2O2 and NO generation are regulated by GPA1, the Gα-subunit of heterotrimeric G proteins. UV-B-dependent H2O2 and NO accumulation were nullified in gpa1 knockout mutants but enhanced by overexpression of a constitutively active form of GPA1 (cGα). In addition, exogenously applied H2O2 or NO rescued the defect in UV-B-mediated stomatal closure in gpa1 mutants, whereas cGα AtrbohD/AtrbohF and cGα nia1 constructs exhibited a similar response to AtrbohD/AtrbohF and Nia1, respectively. Finally, we demonstrated that Gα activation of NO production depends on H2O2. The mutants of AtrbohD and AtrbohF had impaired NO generation in response to UV-B, but UV-B-induced H2O2 accumulation was not impaired in Nia1. Moreover, exogenously applied NO rescued the defect in UV-B-mediated stomatal closure in the mutants of AtrbohD and AtrbohF. These findings establish a signaling pathway leading to UV-B-induced stomatal closure that involves GPA1-dependent activation of H2O2 production and subsequent Nia1-dependent NO accumulation.
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Affiliation(s)
- Jun-Min He
- School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
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106
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Susceptibility of intact germinating Arabidopsis thaliana to human fungal pathogens Cryptococcus neoformans and C. gattii. Appl Environ Microbiol 2013; 79:2979-88. [PMID: 23435895 DOI: 10.1128/aem.03697-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fungus Cryptococcus contributes a large global burden of infectious death in both HIV-infected and healthy individuals. As Cryptococcus is an opportunistic pathogen, much of the evolutionary pressure shaping virulence occurs in environments in contact with plants and soil. The present studies investigated inoculation of intact seeds of the common weed Arabidopsis thaliana with fungal cells over a 21-day period. C. gattii was the more virulent plant pathogen, resulting in disrupted germination as well as increased stem lodging, fungal burden, and plant tissue colocalization. C. neoformans was a less virulent plant pathogen but exhibited prolonged tissue residence within the cuticle and vascular spaces. Arabidopsis mutants of the PRN1 gene, which is involved in abiotic and biotic signaling affecting phenylalanine-derived flavonoids, showed altered susceptibility to cryptoccocal infections, suggesting roles for this pathway in cryptococcal defense. The fungal virulence factor laccase was also implicated in plant pathogenesis, as a cryptococcal lac1Δ strain was less virulent than wild-type fungi and was unable to colonize seedlings. In conclusion, these studies expand knowledge concerning the ecological niche of Cryptococcus by demonstrating the pathogenic capacity of the anamorphic form of cryptococcal cells against healthy seedlings under physiologically relevant conditions. In addition, an important role of laccase in plant as well as human virulence may suggest mechanisms for laccase retention and optimization during evolution of this fungal pathogen.
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107
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Wu W, Huang J. Functional analysis of heterotrimeric G proteins in chloroplast development in Arabidopsis. Methods Mol Biol 2013; 1043:81-7. [PMID: 23913038 DOI: 10.1007/978-1-62703-532-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Functional analysis of G-proteins has been extensively carried out using their over-expressing lines and knockout mutants in plants. Since α subunit exists in an active or inactive form, overexpressing α subunit does not mean that G-protein signaling pathways are activated in the transgenic lines. Ectopic expression of the constitutively active form of the α subunit will magnify a role of G-protein signaling pathways in plant growth and development, and ultimately yield phenotypes. Here, we describe the method to study function of G-proteins in chloroplast development using the constitutively active form of the α subunit in Arabidopsis.
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Affiliation(s)
- Wenjuan Wu
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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108
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Mu J, Tan H, Hong S, Liang Y, Zuo J. Arabidopsis transcription factor genes NF-YA1, 5, 6, and 9 play redundant roles in male gametogenesis, embryogenesis, and seed development. MOLECULAR PLANT 2013; 6:188-201. [PMID: 22933713 DOI: 10.1093/mp/sss061] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nuclear factor Y (NF-Y) is a highly conserved transcription factor presented in all eukaryotic organisms, and is a heterotrimer consisting of three subunits: NF-YA, NF-YB, and NF-YC. In Arabidopsis, these three subunits are encoded by multigene families. The best-studied member of the NF-Y transcription factors is LEAFY COTYLEDON1 (LEC1), a NF-YB family member, which plays a critical role in embryogenesis and seed maturation. However, the function of most NF-Y genes remains elusive. Here, we report the characterization of four genes in the NF-YA family. We found that a gain-of-function mutant of NF-YA1 showed defects in male gametogenesis and embryogenesis. Consistently, overexpression of NF-YA1, 5, 6, and 9 affects male gametogenesis, embryogenesis, seed morphology, and seed germination, with a stronger phenotype when overexpressing NF-YA1 and NF-YA9. Moreover, overexpression of these NF-YA genes also causes hypersensitivity to abscisic acid (ABA) during seed germination, retarded seedling growth, and late flowering at different degrees. Intriguingly, overexpression of NF-YA1, 5, 6, and 9 is sufficient to induce the formation of somatic embryos from the vegetative tissues. However, single or double mutants of these NF-YA genes do not have detectable phenotype. Collectively, these results provide evidence that NF-YA1, 5, 6, and 9 play redundant roles in male gametophyte development, embryogenesis, seed development, and post-germinative growth.
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Affiliation(s)
- Jinye Mu
- State Key Laboratory of Plant Genomics and National Plant Gene Research Center-Beijing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
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109
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Junker A, Bäumlein H. Multifunctionality of the LEC1 transcription factor during plant development. PLANT SIGNALING & BEHAVIOR 2012; 7:1718-20. [PMID: 23073004 PMCID: PMC3578918 DOI: 10.4161/psb.22365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
LEC1 acts as a key regulator of embryogenesis in Arabidopsis thaliana, but is involved in a wide range of functions, all the way from embryo morphogenesis to seed maturation. New data show that LEC1, partially in conjunction with abscisic acid, affects auxin synthesis, and both brassinosteroid and light signaling. The phenotype of LEC1 overexpressors confirms LEC1's known participation in the regulation of somatic embryogenesis, but also indicates additional roles in embryonic and extra-embryonic cell elongation. Here we present an integrated model of LEC1 function and suggest potential directions to be taken in future research in this important area of plant science.
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Affiliation(s)
- Astrid Junker
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.
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110
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Petroni K, Kumimoto RW, Gnesutta N, Calvenzani V, Fornari M, Tonelli C, Holt BF, Mantovani R. The promiscuous life of plant NUCLEAR FACTOR Y transcription factors. THE PLANT CELL 2012; 24:4777-92. [PMID: 23275578 PMCID: PMC3556957 DOI: 10.1105/tpc.112.105734] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 11/23/2012] [Accepted: 12/10/2012] [Indexed: 05/18/2023]
Abstract
The CCAAT box is one of the most common cis-elements present in eukaryotic promoters and is bound by the transcription factor NUCLEAR FACTOR Y (NF-Y). NF-Y is composed of three subunits, NF-YA, NF-YB, and NF-YC. Unlike animals and fungi, plants have significantly expanded the number of genes encoding NF-Y subunits. We provide a comprehensive classification of NF-Y genes, with a separation of closely related, but distinct, histone fold domain proteins. We additionally review recent experiments that have placed NF-Y at the center of many developmental stress-responsive processes in the plant lineage.
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Affiliation(s)
- Katia Petroni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
| | - Roderick W. Kumimoto
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019
| | - Nerina Gnesutta
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
| | - Valentina Calvenzani
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
| | - Monica Fornari
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
| | - Chiara Tonelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
| | - Ben F. Holt
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019
| | - Roberto Mantovani
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy
- Address correspondence to
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111
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Trusov Y, Chakravorty D, Botella JR. Diversity of heterotrimeric G-protein γ subunits in plants. BMC Res Notes 2012; 5:608. [PMID: 23113884 PMCID: PMC3508898 DOI: 10.1186/1756-0500-5-608] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/15/2012] [Indexed: 12/13/2022] Open
Abstract
Background Heterotrimeric G-proteins, consisting of three subunits Gα, Gβ and Gγ are present in most eukaryotes and mediate signaling in numerous biological processes. In plants, Gγ subunits were shown to provide functional selectivity to G-proteins. Three unconventional Gγ subunits were recently reported in Arabidopsis, rice and soybean but no structural analysis has been reported so far. Their relationship with conventional Gγ subunits and taxonomical distribution has not been yet demonstrated. Results After an extensive similarity search through plant genomes, transcriptomes and proteomes we assembled over 200 non-redundant proteins related to the known Gγ subunits. Structural analysis of these sequences revealed that most of them lack the obligatory C-terminal prenylation motif (CaaX). According to their C-terminal structures we classified the plant Gγ subunits into three distinct types. Type A consists of Gγ subunits with a putative prenylation motif. Type B subunits lack a prenylation motif and do not have any cysteine residues in the C-terminal region, while type C subunits contain an extended C-terminal domain highly enriched with cysteines. Comparative analysis of C-terminal domains of the proteins, intron-exon arrangement of the corresponding genes and phylogenetic studies suggested a common origin of all plant Gγ subunits. Conclusion Phylogenetic analyses suggest that types C and B most probably originated independently from type A ancestors. We speculate on a potential mechanism used by those Gγ subunits lacking isoprenylation motifs to anchor the Gβγ dimer to the plasma membrane and propose a new flexible nomenclature for plant Gγ subunits. Finally, in the light of our new classification, we give a word of caution about the interpretation of Gγ research in Arabidopsis and its generalization to other plant species.
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Affiliation(s)
- Yuri Trusov
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, 4072, Australia
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112
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Fox AR, Soto GC, Jones AM, Casal JJ, Muschietti JP, Mazzella MA. cry1 and GPA1 signaling genetically interact in hook opening and anthocyanin synthesis in Arabidopsis. PLANT MOLECULAR BIOLOGY 2012; 80:315-24. [PMID: 22855128 PMCID: PMC4871592 DOI: 10.1007/s11103-012-9950-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/23/2012] [Indexed: 05/08/2023]
Abstract
While studying blue light-independent effects of cryptochrome 1 (cry1) photoreceptor, we observed premature opening of the hook in cry1 mutants grown in complete darkness, a phenotype that resembles the one described for the heterotrimeric G-protein α subunit (GPA1) null mutant gpa1. Both cry1 and gpa1 also showed reduced accumulation of anthocyanin under blue light. These convergent gpa1 and cry1 phenotypes required the presence of sucrose in the growth media and were not additive in the cry1 gpa1 double mutant, suggesting context-dependent signaling convergence between cry1 and GPA1 signaling pathways. Both, gpa1 and cry1 mutants showed reduced GTP-binding activity. The cry1 mutant showed wild-type levels of GPA1 mRNA or GPA1 protein. However, an anti-transducin antibody (AS/7) typically used for plant Gα proteins, recognized a 54 kDa band in the wild type but not in gpa1 and cry1 mutants. We propose a model where cry1-mediated post-translational modification of GPA1 alters its GTP-binding activity.
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Affiliation(s)
- Ana R. Fox
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Hector Torres, (INGEBI-CONICET), Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina
| | - Gabriela C. Soto
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Hector Torres, (INGEBI-CONICET), Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina
| | - Alan M. Jones
- Departments of Biology and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jorge J. Casal
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, 1417 Buenos Aires, Argentina
- Fundacion Instituto Leloir, 1405 Buenos Aires, Argentina
| | - Jorge P. Muschietti
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Hector Torres, (INGEBI-CONICET), Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina
| | - María A. Mazzella
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Hector Torres, (INGEBI-CONICET), Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina
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113
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Interactions and CCAAT-binding of Arabidopsis thaliana NF-Y subunits. PLoS One 2012; 7:e42902. [PMID: 22912760 PMCID: PMC3422339 DOI: 10.1371/journal.pone.0042902] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/12/2012] [Indexed: 12/04/2022] Open
Abstract
Background NF-Y is a transcription factor that recognizes with high specificity and affinity the widespread CCAAT box promoter element. It is formed by three subunits: NF-YA and the NF-YB/NF-YC- heterodimer containing histone fold domains (HFDs). We previously identified a large NF-Y gene family in Arabidopsis thaliana, composed of 29 members, and characterized their expression patterns in various plant tissues. Methods We used yeast Two-hybrids assays (Y2H), pull-down and Electrophoretic Mobility Shift Assay (EMSA) in vitro experiments with recombinant proteins to dissect AtNF-YB/AtNF-YC interactions and DNA-binding with different AtNF-YAs. Results Consistent with robust conservation within HFDs, we show that heterodimerization is possible among all histone-like subunits, including the divergent and related LEC1/AtNF-YB9 and L1L/AtNF-YB6 required for embryo development. DNA-binding to a consensus CCAAT box was investigated with specific AtNF-YB/AtNF-YC combinations and observed with some, but not all AtNF-YA subunits. Conclusions Our results highlight (i) the conserved heterodimerization capacity of AtNF-Y histone-like subunits, and (ii) the different affinities of AtNF-YAs for the CCAAT sequence. Because of the general expansion of NF-Y genes in plants, these results most likely apply to other species.
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114
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Junker A, Mönke G, Rutten T, Keilwagen J, Seifert M, Thi TMN, Renou JP, Balzergue S, Viehöver P, Hähnel U, Ludwig-Müller J, Altschmied L, Conrad U, Weisshaar B, Bäumlein H. Elongation-related functions of LEAFY COTYLEDON1 during the development of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 71:427-42. [PMID: 22429691 DOI: 10.1111/j.1365-313x.2012.04999.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The transcription factor LEAFY COTYLEDON1 (LEC1) controls aspects of early embryogenesis and seed maturation in Arabidopsis thaliana. To identify components of the LEC1 regulon, transgenic plants were derived in which LEC1 expression was inducible by dexamethasone treatment. The cotyledon-like leaves and swollen root tips developed by these plants contained seed-storage compounds and resemble the phenotypes produced by increased auxin levels. In agreement with this, LEC1 was found to mediate up-regulation of the auxin synthesis gene YUCCA10. Auxin accumulated primarily in the elongation zone at the root-hypocotyl junction (collet). This accumulation correlates with hypocotyl growth, which is either inhibited in LEC1-induced embryonic seedlings or stimulated in the LEC1-induced long-hypocotyl phenotype, therefore resembling etiolated seedlings. Chromatin immunoprecipitation analysis revealed a number of phytohormone- and elongation-related genes among the putative LEC1 target genes. LEC1 appears to be an integrator of various regulatory events, involving the transcription factor itself as well as light and hormone signalling, especially during somatic and early zygotic embryogenesis. Furthermore, the data suggest non-embryonic functions for LEC1 during post-germinative etiolation.
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Affiliation(s)
- Astrid Junker
- Leibniz Institute of Plant Genetics and Crop Plant Research, Corrensstraße 3, D-06466 Gatersleben, Germany.
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115
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Hackenberg D, Wu Y, Voigt A, Adams R, Schramm P, Grimm B. Studies on differential nuclear translocation mechanism and assembly of the three subunits of the Arabidopsis thaliana transcription factor NF-Y. MOLECULAR PLANT 2012; 5:876-88. [PMID: 22199235 DOI: 10.1093/mp/ssr107] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The eukaryotic transcription factor NF-Y consists of three subunits (A, B, and C), which are encoded in Arabidopsis thaliana in multigene families consisting of 10, 13, and 13 genes, respectively. In principle, all potential combinations of the subunits are possible for the assembly of the heterotrimeric complex. We aimed at assessing the probability of each subunit to participate in the assembly of NF-Y. The evaluation of physical interactions among all members of the NF-Y subunit families indicate a strong requirement for NF-YB/NF-YC heterodimerization before the entire complex can be accomplished. By means of a modified yeast two-hybrid system assembly of all three subunits to a heterotrimeric complex was demonstrated. Using GFP fusion constructs, NF-YA and NF-YC localization in the nucleus was demonstrated, while NF-YB is solely imported into the nucleus as a NF-YC-associated heterodimer NF-YC. This piggyback transport of the two Arabidopsis subunits differs from the import of the NF-Y heterotrimer of heterotrophic organisms. Based on a peptide structure model of the histone-fold-motifs, disulfide bonding among intramolecular conserved cysteine residues of NF-YB, which is responsible for the redox-regulated assembly of NF-YB and NF-YC in human and Aspergillus nidulans, can be excluded for Arabidopsis NF-YB.
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Affiliation(s)
- Dieter Hackenberg
- Institute of Biology/Plant Physiology, Humboldt University, Berlin, Germany
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Park SH, Chung PJ, Juntawong P, Bailey-Serres J, Kim YS, Jung H, Bang SW, Kim YK, Do Choi Y, Kim JK. Posttranscriptional control of photosynthetic mRNA decay under stress conditions requires 3' and 5' untranslated regions and correlates with differential polysome association in rice. PLANT PHYSIOLOGY 2012; 159:1111-24. [PMID: 22566494 PMCID: PMC3387698 DOI: 10.1104/pp.112.194928] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/02/2012] [Indexed: 05/18/2023]
Abstract
Abiotic stress, including drought, salinity, and temperature extremes, regulates gene expression at the transcriptional and posttranscriptional levels. Expression profiling of total messenger RNAs (mRNAs) from rice (Oryza sativa) leaves grown under stress conditions revealed that the transcript levels of photosynthetic genes are reduced more rapidly than others, a phenomenon referred to as stress-induced mRNA decay (SMD). By comparing RNA polymerase II engagement with the steady-state mRNA level, we show here that SMD is a posttranscriptional event. The SMD of photosynthetic genes was further verified by measuring the half-lives of the small subunit of Rubisco (RbcS1) and Chlorophyll a/b-Binding Protein1 (Cab1) mRNAs during stress conditions in the presence of the transcription inhibitor cordycepin. To discern any correlation between SMD and the process of translation, changes in total and polysome-associated mRNA levels after stress were measured. Total and polysome-associated mRNA levels of two photosynthetic (RbcS1 and Cab1) and two stress-inducible (Dehydration Stress-Inducible Protein1 and Salt-Induced Protein) genes were found to be markedly similar. This demonstrated the importance of polysome association for transcript stability under stress conditions. Microarray experiments performed on total and polysomal mRNAs indicate that approximately half of all mRNAs that undergo SMD remain polysome associated during stress treatments. To delineate the functional determinant(s) of mRNAs responsible for SMD, the RbcS1 and Cab1 transcripts were dissected into several components. The expressions of different combinations of the mRNA components were analyzed under stress conditions, revealing that both 3' and 5' untranslated regions are necessary for SMD. Our results, therefore, suggest that the posttranscriptional control of photosynthetic mRNA decay under stress conditions requires both 3' and 5' untranslated regions and correlates with differential polysome association.
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Affiliation(s)
- Su-Hyun Park
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Pil Joong Chung
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Piyada Juntawong
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Julia Bailey-Serres
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Youn Shic Kim
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Harin Jung
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Seung Woon Bang
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Yeon-Ki Kim
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Yang Do Choi
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
| | - Ju-Kon Kim
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449–728, Korea (S.-H.P., P.J.C., Y.S.K., H.J., S.W.B., J.-K.K.); Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065 (P.J.C.); Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 (P.J., J.B.-S.); GreenGene Biotech, Inc., Myongji University, Yongin 449–728, Korea (Y.-K.K.); and School of Agricultural Biotechnology, Seoul National University, Seoul 151–921, Korea (Y.D.C.)
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Ding D, Wang Y, Han M, Fu Z, Li W, Liu Z, Hu Y, Tang J. MicroRNA transcriptomic analysis of heterosis during maize seed germination. PLoS One 2012; 7:e39578. [PMID: 22761829 PMCID: PMC3384671 DOI: 10.1371/journal.pone.0039578] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 05/23/2012] [Indexed: 12/13/2022] Open
Abstract
Heterosis has been utilized widely in the breeding of maize and other crops, and plays an important role in increasing yield, improving quality and enhancing stresses resistance, but the molecular mechanism responsible for heterosis is far from clear. To illustrate whether miRNA-dependent gene regulation is responsible for heterosis during maize germination, a deep-sequencing technique was applied to germinating embryos of a maize hybrid, Yuyu22, which is cultivated widely in China and its parental inbred lines, Yu87-1 and Zong3. The target genes of several miRNAs showing significant expression in the hybrid and parental lines were predicted and tested using real-time PCR. A total of 107 conserved maize miRNAs were co-detected in the hybrid and parental lines. Most of these miRNAs were expressed non-additively in the hybrid compared to its parental lines. These results indicated that miRNAs might participate in heterosis during maize germination and exert an influence via the decay of their target genes. Novel miRNAs were predicted follow a rigorous criterion and only the miRNAs detected in all three samples were treated as a novel maize miRNA. In total, 34 miRNAs belonged to 20 miRNA families were predicted in germinating maize seeds. Global repression of miRNAs in the hybrid, which might result in enhanced gene expression, might be one reason why the hybrid showed higher embryo germination vigor compared to its parental lines.
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Affiliation(s)
- Dong Ding
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Yinju Wang
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Mingshui Han
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Zhiyuan Fu
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Weihua Li
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Zonghua Liu
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Yanmin Hu
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Jihua Tang
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
- * E-mail:
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Liu F, Bian Z, Jia Z, Zhao Q, Song S. The GCR1 and GPA1 participate in promotion of Arabidopsis primary root elongation induced by N-acyl-homoserine lactones, the bacterial quorum-sensing signals. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:677-83. [PMID: 22250582 DOI: 10.1094/mpmi-10-11-0274] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Many gram-negative bacteria use N-acyl-homoserine lactones (AHL) as quorum-sensing signals to coordinate their collective behaviors. Accumulating evidence indicates that plants can respond to AHL. However, little is known about the molecular mechanism of plants reacting to these bacterial signals. In this study, we show that the treatment of Arabidopsis roots with N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) and N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) resulted in significant root elongation. The genetic analysis revealed that the T-DNA insertional mutants of gcr1, encoding a G-protein-coupled receptor GCR1, were insensitive to 3OC6-HSL or 3OC8-HSL in assays of root growth. The loss-of-function mutants of the sole canonical Gα subunit GPA1 showed no response to AHL promotion of root elongation whereas Gα gain-of-function plants overexpressing either the wild type or a constitutively active version of Arabidopsis Gα exhibited the exaggerated effect on root elongation caused by AHL. Furthermore, the expression of GCR1 and GPA1 were significantly upregulated after plants were contacted with both AHL. Taken together, our results suggest that GCR1 and GPA1 are involved in AHL-mediated elongation of Arabidopsis roots. This provides insight into the mechanism of plant responses to bacterial quorum-sensing signals.
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Affiliation(s)
- Fang Liu
- Biology Institute, Hebei Academy of Sciences and Hebei Engineering and Technology Center of Microbiological Control on Main Crop Disease, 46th South Street of Friendship, Shijiazhuang 050051, China
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Liang M, Hole D, Wu J, Blake T, Wu Y. Expression and functional analysis of NUCLEAR FACTOR-Y, subunit B genes in barley. PLANTA 2012; 235:779-91. [PMID: 22042327 DOI: 10.1007/s00425-011-1539-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Accepted: 10/12/2011] [Indexed: 05/10/2023]
Abstract
NUCLEAR FACTOR-Y, subunit B (NF-YB) comprises a multigene family in plants and has been shown to play important roles in growth, development, and response to environmental stress. In this study, five NF-YBs containing the full-length coding region were obtained from barley (Hordeum vulgare) through database sequence analysis, cloning, and sequencing. Sequence alignment and phylogenetic analysis showed that HvNF-YB3 and HvNF-YB1 were clustered with NF-YB2 and NF-YB3 in Arabidopsis, suggesting these NF-YBs are evolutionary and functionally related. To test this hypothesis, HvNF-YB3 and HvNF-YB1 were overexpressed in Arabidopsis. Overexpression of HvNF-YB1 greatly promoted early flowering in Arabidopsis, supporting that HvNF-YB1may have conserved gene function in flowering time control as NF-YB2 and NF-YB3 in Arabidopsis. Overexpression of HvNF-YB3 in Arabidopsis had no effect on flowering time. An analysis of barley single-nucleotide polymorphism (SNP) data, however, revealed a significant association between an HvNF-YB3 SNP and heading date. While it is unknown whether HvNF-YB3 directly contributes to heading date regulation, the results implied that HvNF-YB3 may also have conserved function in flowering time (heading date in barley) control. Further studies are needed to directly verify these gene functions in barley. Barley NF-YBs showed different expression patterns associated with tissue types, developmental stages, and response to different stress treatments, suggesting that barley NF-YBs may be involved in other physiological processes.
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Affiliation(s)
- Mingxiang Liang
- Department of Plants, Soils, and Climate, Utah State University, Logan, UT 84322, USA.
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120
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Chakravorty D, Trusov Y, Botella JR. Site-directed mutagenesis of the Arabidopsis heterotrimeric G protein β subunit suggests divergent mechanisms of effector activation between plant and animal G proteins. PLANTA 2012; 235:615-27. [PMID: 22002625 DOI: 10.1007/s00425-011-1526-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/22/2011] [Indexed: 05/23/2023]
Abstract
Heterotrimeric G proteins are integral components of signal transduction in humans and other mammals and have been therefore extensively studied. However, while they are known to mediate many processes, much less is currently known about the effector pathways and molecular mechanisms used by these proteins to regulate effectors in plants. We designed a complementation strategy to study G protein signaling in Arabidopsis thaliana, particularly the mechanism of action of AGB1, the sole identified β subunit. We used biochemical and effector regulation data from human G protein studies to identify four potentially important residues for site-directed mutagenesis (T65, M111, D250 and W361 of AGB1). Each residue was individually mutated and the resulting mutated protein introduced in the agb1-2 mutant background under the control of the native AGB1 promoter. Interestingly, even though these mutations have been shown to have profound effects on effector signaling in humans, all the mutated subunits were able to restore thirteen of the fifteen Gβ-deficient phenotypes characterized in this study. Only one mutated protein, T65A was unable to complement the hypersensitivity to mannitol during germination observed in agb1 mutants; while only D250A failed to restore lateral root numbers in the agb1 mutant to wild-type levels. Our results suggest that the mechanisms used in mammalian G protein signaling are not well conserved in plant G protein signaling, and that either the effectors used by plant G proteins, or the mechanisms used to activate them, are at least partially divergent from the well-studied mammalian G proteins.
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Affiliation(s)
- David Chakravorty
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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121
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Salvini M, Sani E, Fambrini M, Pistelli L, Pucciariello C, Pugliesi C. Molecular analysis of a sunflower gene encoding an homologous of the B subunit of a CAAT binding factor. Mol Biol Rep 2012; 39:6449-65. [PMID: 22359114 DOI: 10.1007/s11033-012-1463-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 01/23/2012] [Indexed: 10/28/2022]
Abstract
A genomic DNA fragment containing the complete LEAFY COTYLEDON1-LIKE (HaL1L) gene was retrieved by chromosome walking. Its sequence was confirmed and elongated by screening a sunflower genomic DNA BAC Library. HaL1L, whose cDNA had already been sequenced and characterized, encodes a NF-YB subunit of a CCAAT box-binding factor (NF-Y) involved in the early stages of zygotic and somatic embryogenesis in the Helianthus genus. In the HaL1L 5'-flanking region, elements specific to a putative TATA-box promoter and two "CG isles" were identified. An investigation of the methylation status of these CG rich DNA regions showed that differentially methylated cytosines were recognizable in the DNA of embryos on the fifth day after pollination in comparison to leaf DNA suggesting that during plant development epigenetic regulation of HaL1L transcription was achieved by methylating cytosine residues. We also searched the HaL1L nucleotide sequence for cis-regulatory elements able to interact with other transcription factors (TFs) involved in the HaL1L regulation. Of the elements identified, one of the most intriguing is WUSATA, the target sequence for the WUSCHEL (WUS) TF, which may be part of a complex regulation network controlling embryo development. In this article, we show that the WUSATA target site, located in the intron of HaL1L, is able to bind the TF WUS. Interestingly, we found auxin and abscisic acid responsive motifs in the HaL1L promoter region suggesting that this gene may additionally by under hormonal control. Finally, the presence of a cytoplasmic polyadenylation signal downstream to the coding region indicates that this gene may also be controlled at the translation level by a temporarily making the pre-synthesized HaL1L mRNA unavailable for protein synthesis.
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Bandaranayake PC, Tomilov A, Tomilova NB, Ngo QA, Wickett N, dePamphilis CW, Yoder JI. The TvPirin gene is necessary for haustorium development in the parasitic plant Triphysaria versicolor. PLANT PHYSIOLOGY 2012; 158:1046-53. [PMID: 22128136 PMCID: PMC3271741 DOI: 10.1104/pp.111.186858] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 11/24/2011] [Indexed: 05/06/2023]
Abstract
The rhizosphere is teemed with organisms that coordinate their symbioses using chemical signals traversing between the host root and symbionts. Chemical signals also mediate interactions between roots of different plants, perhaps the most obvious being those between parasitic Orobanchaceae and their plant hosts. Parasitic plants use specific molecules provided by host roots to initiate the development of haustoria, invasive structures critical for plant parasitism. We took a transcriptomics approach to identify parasitic plant genes associated with host factor recognition and haustorium signaling and previously identified a gene, TvPirin, which is transcriptionally up-regulated in roots of the parasitic plant Triphysaria versicolor after being exposed to the haustorium-inducing molecule 2,6-dimethoxybenzoquinone (DMBQ). Because TvPirin shares homology with proteins associated with environmental signaling in some plants, we hypothesized that TvPirin may function in host factor recognition in parasitic plants. We tested the function of TvPirin in T. versicolor roots using hairpin-mediated RNA interference. Reducing TvPirin transcripts in T. versicolor roots resulted in significantly less haustoria development in response to DMBQ exposure. We determined the transcript levels of other root expressed transcripts and found that several had reduced basal levels of gene expression but were similarly regulated by quinone exposure. Phylogenic investigations showed that TvPirin homologs are present in most flowering plants, and we found no evidence of parasite-specific gene duplication or expansion. We propose that TvPirin is a generalized transcription factor associated with the expression of a number of genes, some of which are involved in haustorium development.
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Affiliation(s)
| | | | | | | | | | | | - John I. Yoder
- Department of Crop Science Faculty of Agriculture, University of Peradeniya, Sri Lanka 20400 (P.C.G.B.); Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616 (A.T.); Department of Plant Sciences (N.B.T., J.I.Y.) and Department of Molecular Biosciences, School of Veterinary Medicine (A.T.), University of California, Davis, California 96516; Institute of Plant Biology, University of Zurich, Zurich CH–8008, Switzerland (Q.A.N.); Department of Biology and Huck Institutes of Life Sciences, Penn State University, University Park, Pennsylvania 16802 (N.W., C.W.d.); Plant Science Center, Chicago Botanic Garden, Glencoe, Illinois 60022 (N.W.)
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Zhang H, Wang M, Wang W, Li D, Huang Q, Wang Y, Zheng X, Zhang Z. Silencing of G proteins uncovers diversified plant responses when challenged by three elicitors in Nicotiana benthamiana. PLANT, CELL & ENVIRONMENT 2012; 35:72-85. [PMID: 21895695 DOI: 10.1111/j.1365-3040.2011.02417.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Signalling through heterotrimeric G protein composed of α-, β- and γ-subunits is essential in numerous physiological processes. Here we show that this prototypical G protein complex acts mechanistically by controlling elicitor sensitivity towards hypersensitive response (HR) and stomatal closure in Nicotiana benthamiana. Gα-, Gβ1-, and Gβ2-silenced plants were generated using virus-induced gene silencing. All silenced plants were treated with Xanthomonas oryzae harpin, Magnaporthe oryzae Nep1 and Phytophthora boehmeriae boehmerin, respectively. HR was dramatically impaired in Gα- and Gβ2-silenced plants treated with harpin, indicating that harpin-, rather than Nep1- or boehmerin-triggered HR, is Gα- and Gβ2-dependent. Moreover, all Gα-, Gβ1- and Gβ2-silenced plants significantly impaired elicitor-induced stomatal closure, elicitor-promoted nitric oxide (NO) production and active oxygen species accumulation in guard cells. To our knowledge, this is the first report of Gα and Gβ subunits involvement in stomatal closure in response to elicitors. Furthermore, silencing of Gα, Gβ1 and Gβ2 has an effect on the transcription of plant defence-related genes when challenged by three elicitors. In conclusion, silencing of G protein subunits results in many interesting plant cell responses, revealing that plant immunity systems employ both conserved and distinct G protein pathways to sense elicitors from distinct phytopathogens formed during plant-microbe evolution.
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Affiliation(s)
- Huajian Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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Tong H, Chu C. Brassinosteroid signaling and application in rice. J Genet Genomics 2011; 39:3-9. [PMID: 22293112 DOI: 10.1016/j.jgg.2011.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/14/2011] [Accepted: 12/14/2011] [Indexed: 11/26/2022]
Abstract
Combined approaches with genetics, biochemistry, and proteomics studies have greatly advanced our understanding of brassinosteroid (BR) signaling in Arabidopsis. However, in rice, a model plant of monocot and as well an important crop plant, BR signaling is not as well characterized as in Arabidopsis. Recent studies by forward and reverse genetics have identified a number of either conserved or specific components of rice BR signaling pathway, bringing new ideas into BR signaling regulation mechanisms. Genetic manipulation of BR level or BR sensitivity to improve rice yield has established the great significance of BR research achievements.
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Affiliation(s)
- Hongning Tong
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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Two G-protein-coupled-receptor candidates, Cand2 and Cand7, are involved in Arabidopsis root growth mediated by the bacterial quorum-sensing signals N-acyl-homoserine lactones. Biochem Biophys Res Commun 2011; 417:991-5. [PMID: 22206669 DOI: 10.1016/j.bbrc.2011.12.066] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 12/14/2011] [Indexed: 11/21/2022]
Abstract
Many Gram-negative bacteria use N-acyl-homoserine lactones (AHLs) as quorum sensing (QS) signaling molecules to coordinate their group behavior. Recently, it was shown that plants can perceive and respond to these bacterial AHLs. However, little is known about the molecular mechanism underlying the response of plants to bacterial QS signals. In this study, we show that the promotion of root elongation in wild type Arabidopsis thaliana induced by the AHLs N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) or N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) was completely abolished in plants with loss-of-function mutations in two candidate G-protein Coupled Receptors (GPCRs), Cand2 and Cand7. Furthermore, real-time PCR analysis revealed that the expression levels of Cand2 and Cand7 were elevated in plants treated with 3OC6-HSL or 3OC8-HSL. These results suggest that Cand2 and Cand7 are involved in the regulation of root growth by bacterial AHLs and that GPCRs play a role in mediating interactions between plants and microbes.
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Chakravorty D, Trusov Y, Zhang W, Acharya BR, Sheahan MB, McCurdy DW, Assmann SM, Botella JR. An atypical heterotrimeric G-protein γ-subunit is involved in guard cell K⁺-channel regulation and morphological development in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 67:840-51. [PMID: 21575088 DOI: 10.1111/j.1365-313x.2011.04638.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Currently, there are strong inconsistencies in our knowledge of plant heterotrimeric G-proteins that suggest the existence of additional members of the family. We have identified a new Arabidopsis G-protein γ-subunit (AGG3) that modulates morphological development and ABA-regulation of stomatal aperture. AGG3 strongly interacts with the Arabidopsis G-protein β-subunit in vivo and in vitro. Most importantly, AGG3-deficient mutants account for all but one of the 'orphan' phenotypes previously unexplained by the two known γ-subunits in Arabidopsis. AGG3 has unique characteristics never before observed in plant or animal systems, such as its size (more than twice that of canonical γ-subunits) and the presence of a C-terminal Cys-rich domain. AGG3 thus represent a novel class of G-protein γ-subunits, widely spread throughout the plant kingdom but not present in animals. Homologues of AGG3 in rice have been identified as important quantitative trait loci for grain size and yield, but due to the atypical nature of the proteins their identity as G-protein subunits was thus far unknown. Our work demonstrates a similar trend in seeds of Arabidopsis agg3 mutants, and implicates G-proteins in such a crucial agronomic trait. The discovery of this highly atypical subunit reinforces the emerging notion that plant and animal G-proteins have distinct as well as shared evolutionary pathways.
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Affiliation(s)
- David Chakravorty
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, Qld 4072, Australia
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127
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Choudhury SR, Bisht NC, Thompson R, Todorov O, Pandey S. Conventional and novel Gγ protein families constitute the heterotrimeric G-protein signaling network in soybean. PLoS One 2011; 6:e23361. [PMID: 21853116 PMCID: PMC3154445 DOI: 10.1371/journal.pone.0023361] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/13/2011] [Indexed: 12/22/2022] Open
Abstract
Heterotrimeric G-proteins comprised of Gα, Gβ and Gγ proteins are important signal transducers in all eukaryotes. The Gγ protein of the G-protein heterotrimer is crucial for its proper targeting at the plasma membrane and correct functioning. Gγ proteins are significantly smaller and more diverse than the Gα and Gβ proteins. In model plants Arabidopsis and rice that have a single Gα and Gβ protein, the presence of two canonical Gγ proteins provide some diversity to the possible heterotrimeric combinations. Our recent analysis of the latest version of the soybean genome has identified ten Gγ proteins which belong to three distinct families based on their C-termini. We amplified the full length cDNAs, analyzed their detailed expression profile by quantitative PCR, assessed their localization and performed yeast-based interaction analysis to evaluate interaction specificity with different Gβ proteins. Our results show that ten Gγ genes are retained in the soybean genome and have interesting expression profiles across different developmental stages. Six of the newly identified proteins belong to two plant-specific Gγ protein families. Yeast-based interaction analyses predict some degree of interaction specificity between different Gβ and Gγ proteins. This research thus identifies a highly diverse G-protein network from a plant species. Homologs of these novel proteins have been previously identified as QTLs for grain size and yield in rice.
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Affiliation(s)
- Swarup Roy Choudhury
- Donald Danforth Plant Science Center, St. Louis, Missouri, United States of America
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128
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Ito Y, Thirumurugan T, Serizawa A, Hiratsu K, Ohme-Takagi M, Kurata N. Aberrant vegetative and reproductive development by overexpression and lethality by silencing of OsHAP3E in rice. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2011; 181:105-110. [PMID: 21683874 DOI: 10.1016/j.plantsci.2011.04.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 04/19/2011] [Accepted: 04/19/2011] [Indexed: 05/30/2023]
Abstract
We generated transgenic rice plants overexpressing OsHAP3E which encodes a subunit of a CCAAT-motif binding HAP complex. The OsHAP3E-overexpressing plants showed various abnormal morphologies both in their vegetative and reproductive phases. The OsHAP3E-overexpressing plants were dwarf with erected leaves and similar to brassinosteroid mutants in the vegetative phase. In the reproductive phase, dense panicle was developed, and occasionally successive generation of lateral rachises and formation of double flowers were observed. These phenotypes indicate association of OsHAP3E with determination of floral meristem identity. On the other hand, repression of OsHAP3E by RNAi or by overexpressing chimeric repressor fusion constructs brought about lethality to transformed cells, and almost no transformant was obtained. This suggests that the OsHAP3E function is essential for rice cells. Altogether, our loss-of-function and gain-of-function analyses suggest that OsHAP3E plays important pleiotropic roles in vegetative and reproductive development or basic cellular processes in rice.
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Affiliation(s)
- Yukihiro Ito
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
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129
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Yadav DK, Tuteja N. Rice G-protein coupled receptor (GPCR): in silico analysis and transcription regulation under abiotic stress. PLANT SIGNALING & BEHAVIOR 2011; 6:1079-86. [PMID: 21778827 PMCID: PMC3260697 DOI: 10.4161/psb.6.8.15771] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 05/09/2023]
Abstract
Majority of transmembrane signal transduction in response to diverse external stimuli is mediated by G-protein coupled receptors (GPCRs) and are the principal signal transducers. GPCRs are characterized by seven membrane-spanning domains with an extracellular N-terminus and a cytoplasmic C-terminus which functions along with GTP-binding protein in a highly coordinated fashion. Role of heterotrimeric G-proteins in abiotic stresses has been reported, but the response of GPCR is not yet well characterized. In the present study we report the isolation of one putative GPCR (966 bp) from Indica rice (Oryza sativa cv. Indica group Swarna) and described its transcriptional regulation under abiotic stresses. Amino acid sequence analyses shows the presence of typical heptahelical transmembrane spanning domains with extracellular N-terminus involved in ligand binding and cytoplasm facing C-terminus that binds with heterotrimeric G-protein. Sequence analysis also confirmed the presence of all signature motifs required for functional GPCR. Domain and site prediction shows the presence of myristoylation sites for membrane association, and protein kinase C sites for its desensitization. The transcript levels of rice GPCR was induced following NaCl and ABA treatments. However, in drought condition the expression profile of GPCR up regulated during early exposure which subsequently decreased. On the other hand it seems no significant effect due to cold and heat stress. These findings provide a direct evidence for transcriptional regulation of rice GPCR under abiotic stress conditions. These findings also suggest that GPCR can be exploited for promoting stress tolerance in plants.
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Affiliation(s)
- Dinesh Kumar Yadav
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
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130
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Cao S, Kumimoto RW, Siriwardana CL, Risinger JR, Holt BF. Identification and characterization of NF-Y transcription factor families in the monocot model plant Brachypodium distachyon. PLoS One 2011; 6:e21805. [PMID: 21738795 PMCID: PMC3128097 DOI: 10.1371/journal.pone.0021805] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 06/07/2011] [Indexed: 11/19/2022] Open
Abstract
Background Nuclear Factor Y (NF-Y) is a heterotrimeric transcription factor composed of NF-YA, NF-YB and NF-YC proteins. Using the dicot plant model system Arabidopsis thaliana (Arabidopsis), NF-Y were previously shown to control a variety of agronomically important traits, including drought tolerance, flowering time, and seed development. The aim of the current research was to identify and characterize NF-Y families in the emerging monocot model plant Brachypodium distachyon (Brachypodium) with the long term goal of assisting in the translation of known dicot NF-Y functions to the grasses. Methodology/Principal Findings We identified, annotated, and further characterized 7 NF-YA, 17 NF-YB, and 12 NF-YC proteins in Brachypodium (BdNF-Y). By examining phylogenetic relationships, orthology predictions, and tissue-specific expression patterns for all 36 BdNF-Y, we proposed numerous examples of likely functional conservation between dicots and monocots. To test one of these orthology predictions, we demonstrated that a BdNF-YB with predicted orthology to Arabidopsis floral-promoting NF-Y proteins can rescue a late flowering Arabidopsis mutant. Conclusions/Significance The Brachypodium genome encodes a similar complement of NF-Y to other sequenced angiosperms. Information regarding NF-Y phylogenetic relationships, predicted orthologies, and expression patterns can facilitate their study in the grasses. The current data serves as an entry point for translating many NF-Y functions from dicots to the genetically tractable monocot model system Brachypodium. In turn, studies of NF-Y function in Brachypodium promise to be more readily translatable to the agriculturally important grasses.
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Affiliation(s)
- Shuanghe Cao
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Roderick W. Kumimoto
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Chamindika L. Siriwardana
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Jan R. Risinger
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Ben F. Holt
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
- * E-mail:
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131
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Ballif J, Endo S, Kotani M, MacAdam J, Wu Y. Over-expression of HAP3b enhances primary root elongation in Arabidopsis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:579-83. [PMID: 21316979 DOI: 10.1016/j.plaphy.2011.01.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 12/20/2010] [Accepted: 01/11/2011] [Indexed: 05/20/2023]
Abstract
HAPs, similar to Heme Activator Proteins (HAP) or nuclear factor-Y (NF-Y) in yeast and animals, play versatile roles in plant growth, development, and responses to environmental cues. HAP3b in Arabidopsis is a member in the HAP3 gene family and is involved in regulating flowering time through the long-day photoperiod pathway (Cai et al., 2007, Plant Physiol 145: 98-105). In this study, we report that overexpression of HAP3b enhances primary root elongation. Detailed analysis showed that HAP3b-overexpression did not affect the length of the root elongation zone and the cell length profiles in the elongation zone. Kinematic analysis indicated that root cells in HAP3b-overexpressors elongate faster than the cells in wild-type roots. Using GUS as a reporter gene, we showed that HAP3b is specifically expressed in the tip region of the root, where cell division and elongation occur. Our results provide evidence to support a role of HAP3b in regulation of root growth.
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Affiliation(s)
- Jenny Ballif
- Department of Plants, Soils, and Climate, Utah State University, Logan, UT 84322, USA
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132
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Alvarez S, Hicks LM, Pandey S. ABA-dependent and -independent G-protein signaling in Arabidopsis roots revealed through an iTRAQ proteomics approach. J Proteome Res 2011; 10:3107-22. [PMID: 21545083 DOI: 10.1021/pr2001786] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Heterotrimeric G-proteins are important signal transducers in all eukaryotes. The plant hormone abscisic acid (ABA) has emerged as a key regulator of G-protein-mediated signaling pathways in plants. ABA-regulation of G-protein signaling involves both conventional and novel mechanisms. We have utilized the null mutant of the Arabidopsis G-protein α subunit gpa1 to evaluate to what extent ABA-dependent changes in the proteome are regulated by G-proteins. We used Arabidopsis root tissue as both ABA and G-proteins, individually and in combination, affect root growth and development. We identified 720 proteins, of which 42 showed GPA1-dependent and 74 showed ABA-dependent abundance changes. A majority of ABA-regulated proteins were also GPA1-dependent. Our data provide insight into how tissue specificity might be achieved in ABA-regulated G-protein signaling. A number of proteins related to ER body formation and intracellular trafficking were altered in gpa1 mutant, suggesting a novel role for GPA1 in these pathways. A potential link between ABA metabolism and ABA signaling was also revealed. The comparison of protein abundance changes in the absence of ABA offers clues to the role of GPA1 in ABA-independent signaling pathways, for example, regulation of cell division. These findings substantially contribute to our knowledge of G-protein signaling mechanisms in plants.
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Affiliation(s)
- Sophie Alvarez
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, Missouri 63132, USA
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133
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Wang RS, Pandey S, Li S, Gookin TE, Zhao Z, Albert R, Assmann SM. Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells. BMC Genomics 2011; 12:216. [PMID: 21554708 PMCID: PMC3115880 DOI: 10.1186/1471-2164-12-216] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 05/09/2011] [Indexed: 12/15/2022] Open
Abstract
Background In the presence of drought and other desiccating stresses, plants synthesize and redistribute the phytohormone abscisic acid (ABA). ABA promotes plant water conservation by acting on specialized cells in the leaf epidermis, guard cells, which border and regulate the apertures of stomatal pores through which transpirational water loss occurs. Following ABA exposure, solute uptake into guard cells is rapidly inhibited and solute loss is promoted, resulting in inhibition of stomatal opening and promotion of stomatal closure, with consequent plant water conservation. There is a wealth of information on the guard cell signaling mechanisms underlying these rapid ABA responses. To investigate ABA regulation of gene expression in guard cells in a systematic genome-wide manner, we analyzed data from global transcriptomes of guard cells generated with Affymetrix ATH1 microarrays, and compared these results to ABA regulation of gene expression in leaves and other tissues. Results The 1173 ABA-regulated genes of guard cells identified by our study share significant overlap with ABA-regulated genes of other tissues, and are associated with well-defined ABA-related promoter motifs such as ABREs and DREs. However, we also computationally identified a unique cis-acting motif, GTCGG, associated with ABA-induction of gene expression specifically in guard cells. In addition, approximately 300 genes showing ABA-regulation unique to this cell type were newly uncovered by our study. Within the ABA-regulated gene set of guard cells, we found that many of the genes known to encode ion transporters associated with stomatal opening are down-regulated by ABA, providing one mechanism for long-term maintenance of stomatal closure during drought. We also found examples of both negative and positive feedback in the transcriptional regulation by ABA of known ABA-signaling genes, particularly with regard to the PYR/PYL/RCAR class of soluble ABA receptors and their downstream targets, the type 2C protein phosphatases. Our data also provide evidence for cross-talk at the transcriptional level between ABA and another hormonal inhibitor of stomatal opening, methyl jasmonate. Conclusions Our results engender new insights into the basic cell biology of guard cells, reveal common and unique elements of ABA-regulation of gene expression in guard cells, and set the stage for targeted biotechnological manipulations to improve plant water use efficiency.
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Affiliation(s)
- Rui-Sheng Wang
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
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134
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Stephenson TJ, McIntyre CL, Collet C, Xue GP. TaNF-YB3 is involved in the regulation of photosynthesis genes in Triticum aestivum. Funct Integr Genomics 2011; 11:327-40. [PMID: 21327447 DOI: 10.1007/s10142-011-0212-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 01/05/2011] [Accepted: 01/26/2011] [Indexed: 10/18/2022]
Abstract
Nuclear factor Y (NF-Y) transcription factor is a heterotrimer comprised of three subunits: NF-YA, NF-YB and NF-YC. Each of the three subunits in plants is encoded by multiple genes with differential expression profiles, implying the functional specialisation of NF-Y subunit members in plants. In this study, we investigated the roles of NF-YB members in the light-mediated regulation of photosynthesis genes. We identified two NF-YB members from Triticum aestivum (TaNF-YB3 & 7) which were markedly upregulated by light in the leaves and seedling shoots using quantitative RT-PCR. A genome-wide coexpression analysis of multiple Affymetrix Wheat Genome Array datasets revealed that TaNF-YB3-coexpressed transcripts were highly enriched with the Gene Ontology term photosynthesis. Transgenic wheat lines constitutively overexpressing TaNF-YB3 had a significant increase in the leaf chlorophyll content, photosynthesis rate and early growth rate. Quantitative RT-PCR analysis showed that the expression levels of a number of TaNF-YB3-coexpressed transcripts were elevated in the transgenic wheat lines. The mRNA level of TaGluTR encoding glutamyl-tRNA reductase, which catalyses the rate-limiting step of the chlorophyll biosynthesis pathway, was significantly increased in the leaves of the transgenic wheat. Significant increases in the expression level in the transgenic plant leaves were also observed for four photosynthetic apparatus genes encoding chlorophyll a/b-binding proteins (Lhca4 and Lhcb4) and photosystem I reaction centre subunits (subunit K and subunit N), as well as for a gene coding for chloroplast ATP synthase γ subunit. These results indicate that TaNF-YB3 is involved in the positive regulation of a number of photosynthesis genes in wheat.
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Affiliation(s)
- Troy J Stephenson
- CSIRO Plant Industry, 306 Carmody Road, St Lucia, Brisbane, QLD 4067, Australia.
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135
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Kumimoto RW, Zhang Y, Siefers N, Holt BF. NF-YC3, NF-YC4 and NF-YC9 are required for CONSTANS-mediated, photoperiod-dependent flowering in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 63:379-91. [PMID: 20487380 DOI: 10.1111/j.1365-313x.2010.04247.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
NF-Y transcription factors represent a complex of three proteins called NF-YA, NF-YB and NF-YC. Each protein is highly conserved in eukaryotes, and in the plant lineage has undergone numerous rounds of duplication. Individual NF-Y are emerging as important regulators of several essential plant processes, including embryogenesis, drought resistance, maintenance of meristems in nitrogen-fixing nodules and photoperiod-dependent flowering time. Building on the recent finding that NF-YB2 and NF-YB3 have overlapping functionality in Arabidopsis photoperiod-dependent flowering (Kumimoto et al., 2008), we have identified three NF-YC (NF-YC3, NF-YC4, and NF-YC9) that are also required for flowering, and physically interact in vivo with both NF-YB2 and NF-YB3. Furthermore, NF-YC3, NF-YC4 and NF-YC9 can physically interact with full-length CONSTANS (CO), and are genetically required for CO-mediated floral promotion. Collectively, the present data greatly strengthens and extends the argument that CO utilizes NF-Y transcription factor complexes for the activation of FLOWERING LOCUS T (FT) during photoperiod-dependent floral initiation.
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Affiliation(s)
- Roderick W Kumimoto
- Department of Botany and Microbiology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA
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136
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Nilson SE, Assmann SM. The alpha-subunit of the Arabidopsis heterotrimeric G protein, GPA1, is a regulator of transpiration efficiency. PLANT PHYSIOLOGY 2010; 152:2067-77. [PMID: 20200073 PMCID: PMC2850002 DOI: 10.1104/pp.109.148262] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 02/25/2010] [Indexed: 05/19/2023]
Abstract
Land plants must balance CO2 assimilation with transpiration in order to minimize drought stress and maximize their reproductive success. The ratio of assimilation to transpiration is called transpiration efficiency (TE). TE is under genetic control, although only one specific gene, ERECTA, has been shown to regulate TE. We have found that the alpha-subunit of the heterotrimeric G protein in Arabidopsis (Arabidopsis thaliana), GPA1, is a regulator of TE. gpa1 mutants, despite having guard cells that are hyposensitive to abscisic acid-induced inhibition of stomatal opening, have increased TE under ample water and drought stress conditions and when treated with exogenous abscisic acid. Leaf-level gas-exchange analysis shows that gpa1 mutants have wild-type assimilation versus internal CO2 concentration responses but exhibit reduced stomatal conductance compared with ecotype Columbia at ambient and below-ambient internal CO2 concentrations. The increased TE and reduced whole leaf stomatal conductance of gpa1 can be primarily attributed to stomatal density, which is reduced in gpa1 mutants. GPA1 regulates stomatal density via the control of epidermal cell size and stomata formation. GPA1 promoter::beta-glucuronidase lines indicate that the GPA1 promoter is active in the stomatal cell lineage, further supporting a function for GPA1 in stomatal development in true leaves.
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Affiliation(s)
| | - Sarah M. Assmann
- Biology Department, Pennsylvania State University, University Park, Pennsylvania 16802–5301
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137
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Izawa Y, Takayanagi Y, Inaba N, Abe Y, Minami M, Fujisawa Y, Kato H, Ohki S, Kitano H, Iwasaki Y. Function and expression pattern of the alpha subunit of the heterotrimeric G protein in rice. PLANT & CELL PHYSIOLOGY 2010; 51:271-81. [PMID: 20040584 DOI: 10.1093/pcp/pcp186] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The d1 mutant, which is deficient for the heterotrimeric G-protein alpha subunit (Galpha) gene of rice, shows dwarfism and sets small round seeds. To determine whether dwarfism in d1 is due to a reduction in cell number or to shortened cell length, the cell number of the leaf sheath, the internode, the root and the lemma was compared between Nipponbare, a wild-type rice and d1-5, a d1 allele derived from Nipponbare. Our results indicate that the cell number was reduced in all organs analyzed in d1-5. In addition, cell enlargement was found in roots and lemma of d1-5, although the organ length in d1-5 was shorter than that of wild-type rice. These results suggest that rice Galpha participates in cell proliferation in rice. Western blot analyses using anti-Galpha antibody and RT-PCR analyses indicate that Galpha is mostly expressed in the developing organs. Galpha promoter activity studies using the GUS reporter gene confirmed that the expression of Galpha was highest in developing organs. We conclude that rice Galpha participates in the regulation of cell number in a developmental stage-dependent manner.
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Affiliation(s)
- Yuki Izawa
- Department of Bioscience, Fukui Prefectural University, 4-1-1 Matsuoka Kenjyojima, Eiheiji-cho, Yoshida-gun, Fukui, 910-1195 Japan
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138
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TaNF-YC11, one of the light-upregulated NF-YC members in Triticum aestivum, is co-regulated with photosynthesis-related genes. Funct Integr Genomics 2010; 10:265-76. [PMID: 20111976 DOI: 10.1007/s10142-010-0158-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/27/2009] [Accepted: 01/01/2010] [Indexed: 10/19/2022]
Abstract
Nuclear factor Y (NF-Y) is a heterotrimeric transcription factor complex. Each of the NF-Y subunits (NF-YA, NF-YB and NF-YC) in plants is encoded by multiple genes. Quantitative RT-PCR analysis revealed that five wheat NF-YC members (TaNF-YC5, 8, 9, 11 and 12) were upregulated by light in both the leaf and seedling shoot. Co-expression analysis of Affymetrix wheat genome array datasets revealed that transcript levels of a large number of genes were consistently correlated with those of the TaNF-YC11 and TaNF-YC8 genes in three to four separate Affymetrix array datasets. TaNF-YC11-correlated transcripts were significantly enriched with the Gene Ontology term photosynthesis. Sequence analysis in the promoters of TaNF-YC11-correlated genes revealed the presence of putative NF-Y complex binding sites (CCAAT motifs). Quantitative RT-PCR analysis of a subset of potential TaNF-YC11 target genes showed that ten out of the 13 genes were also light-upregulated in both the leaf and seedling shoot and had significantly correlated expression profiles with TaNF-YC11. The potential target genes for TaNF-YC11 include subunit members from all four thylakoid membrane-bound complexes required for the conversion of solar energy into chemical energy and rate-limiting enzymes in the Calvin cycle. These data indicate that TaNF-YC11 is potentially involved in regulation of photosynthesis-related genes.
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139
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Abstract
Heterotrimeric G proteins (Galpha, Gbeta/Ggamma subunits) constitute one of the most important components of cell signaling cascade. G Protein Coupled Receptors (GPCRs) perceive many extracellular signals and transduce them to heterotrimeric G proteins, which further transduce these signals intracellular to appropriate downstream effectors and thereby play an important role in various signaling pathways. GPCRs exist as a superfamily of integral membrane protein receptors that contain seven transmembrane alpha-helical regions, which bind to a wide range of ligands. Upon activation by a ligand, the GPCR undergoes a conformational change and then activate the G proteins by promoting the exchange of GDP/GTP associated with the Galpha subunit. This leads to the dissociation of Gbeta/Ggamma dimer from Galpha. Both these moieties then become free to act upon their downstream effectors and thereby initiate unique intracellular signaling responses. After the signal propagation, the GTP of Galpha-GTP is hydrolyzed to GDP and Galpha becomes inactive (Galpha-GDP), which leads to its re-association with the Gbeta/Ggamma dimer to form the inactive heterotrimeric complex. The GPCR can also transduce the signal through G protein independent pathway. GPCRs also regulate cell cycle progression. Till to date thousands of GPCRs are known from animal kingdom with little homology among them, but only single GPCR has been identified in plant system. The Arabidopsis GPCR was reported to be cell cycle regulated and also involved in ABA and in stress signaling. Here I have described a general mechanism of signal transduction through GPCR/G proteins, structure of GPCRs, family of GPCRs and plant GPCR and its role.
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Affiliation(s)
- Narendra Tuteja
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
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140
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Yamamoto A, Kagaya Y, Toyoshima R, Kagaya M, Takeda S, Hattori T. Arabidopsis NF-YB subunits LEC1 and LEC1-LIKE activate transcription by interacting with seed-specific ABRE-binding factors. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 58:843-56. [PMID: 19207209 DOI: 10.1111/j.1365-313x.2009.03817.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
LEAFY COTYLEDON 1 (LEC1) plays vital roles in the regulation of seed maturation in Arabidopsis. LEC1 encodes a homolog of yeast HAP3 or mammalian NF-YB/CBF-A subunit of trimeric CCAAT binding factor (CBF). Among the nine paralogs of NF-YB in Arabidopsis, LEC1-LIKE (L1L) is most closely related to LEC1, and can complement the lec1 mutation when expressed under the control of the LEC1 promoter. Although the nature of the B3-type seed maturation regulators as transcription factors have been investigated, knowledge of the molecular action of LEC1 is limited. When co-expressed with NF-YC2 in the presence of ABA, we found that LEC1 or L1L, but not other NF-YBs, activated the promoter of CRUCIFERIN C (CRC), which encodes a seed storage protein. However, additional expression of an NF-YA subunit interfered with the activation. The LEC1/L1L-[NF-YC2] activation depended on ABA-response elements present in the promoter, which led to the finding that LEC1/L1L-[NF-YC2] can strongly activate the CRC promoter in the absence of ABA when co-expressed with a seed-specific ABA-response element (ABRE)-binding factor, bZIP67. Functional coupling of LEC1/L1L-[AtNF-YC2] and bZIP67 was also observed in the regulation of sucrose synthase 2 (SUS2). Immunoprecipitation experiments revealed that L1L and bZIP67 formed a protein complex in vivo. These results demonstrate a novel plant-specific mechanism for NF-Y subunit function that enables LEC1 and L1L to regulate a defined developmental network.
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Affiliation(s)
- Akiko Yamamoto
- Bioscience and Biotechnology Center, Nagoya University, Chikusa-ku, Nagoya, Japan
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141
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Zhang L, Wei Q, Wu W, Cheng Y, Hu G, Hu F, Sun Y, Zhu Y, Sakamoto W, Huang J. Activation of the heterotrimeric G protein alpha-subunit GPA1 suppresses the ftsh-mediated inhibition of chloroplast development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 58:1041-53. [PMID: 19228339 DOI: 10.1111/j.1365-313x.2009.03843.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Heterotrimeric G protein knock-out mutants have no phenotypic defect in chloroplast development, and the connection between the G protein signaling pathway and chloroplast development has only been inferred from pharmaceutical evidence. Thus, whether G protein signaling plays a role in chloroplast development remains an open question. Here, we present genetic evidence, using the leaf-variegated mutant thylakoid formation 1 (thf1), indicating that inactivation or activation of the endogenous G protein alpha-subunit (GPA1) affects chloroplast development, as does the ectopic expression of the constitutively active Galpha-subunit (cGPA1). Molecular biological and genetic analyses showed that FtsH complexes, which are composed of type-A (FtsH1/FtsH5) and type-B (FtsH2/FtsH8) subunits, are required for cGPA1-promoted chloroplast development in thf1. Furthermore, the ectopic expression of cGPA1 rescues the leaf variegation of ftsh2. Consistent with this finding, microarray analysis shows that ectopic expression of cGPA1 partially corrects mis-regulated gene expression in thf1. This overlooked function of G proteins provides new insight into our understanding of the integrative signaling network, which dynamically regulates chloroplast development and function in response to both intracellular and extracellular signals.
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Affiliation(s)
- Lingang Zhang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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142
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Li H, Zhang Z, Huang F, Chang L, Ma Y. MicroRNA expression profiles in conventional and micropropagated strawberry (Fragaria x ananassa Duch.) plants. PLANT CELL REPORTS 2009; 28:891-902. [PMID: 19277667 DOI: 10.1007/s00299-009-0693-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 05/18/2023]
Abstract
MicroRNAs (miRNAs) are a class of small non-coding RNAs which play a critical role in plant growth and development. To detect strawberry miRNAs and discover the expression difference between conventional and micropropagated strawberry plants, we carried out the detection and quantification of strawberry miRNAs by microarray. The main findings were that 74 miRNAs were checked in strawberry plants and four miRNA genes displayed clear expression difference between conventional and micropropagated strawberry plants, including two up-regulated genes (miR535 and miR390) and two down-regulated genes (miR169a and miR169d). The ratios of conventionally propagated strawberry plant/micropropagated strawberry plant for miR535, miR390, miR169a and miR169d were 2.6884, 2.2673, 0.2496 and 0.3814, respectively. Quantitative reverse transcription polymerase chain reaction applied to the two up-regulated genes (miR535 and miR390) validated the microarray result. This is the first report on differential expression of miRNAs in conventional and micropropagated plants.
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Affiliation(s)
- He Li
- College of Horticulture, Shenyang Agricultural University, Dongling Road 120, 110161, Shenyang, Liaoning, People's Republic of China
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143
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Chen YH, Lin YT, Lee GH. Novel and unexpected functions of zebrafish CCAAT box binding transcription factor (NF-Y) B subunit during cartilages development. Bone 2009; 44:777-84. [PMID: 19442608 DOI: 10.1016/j.bone.2009.01.374] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 09/30/2008] [Accepted: 01/18/2009] [Indexed: 11/22/2022]
Abstract
We used zebrafish as a model to study the biological functions of NF-YB during early development. Both RT-PCR and whole-mount in situ hybridization experiments revealed that nf-yb was a maternally inherited gene. Later, its expression was restricted in the future head cartilages as well as in the developing notochord. Embryos after injection with nf-yb-morpholino displayed reduced-head phenotypes, including smaller head (WT, length of head, L: 0.515+/-0.019 mm, width of head, W: 0.323+/-0.077 mm; nf-yb-morphant, L: 0.347+/-0.037 mm; W: 0.266+/-0.018 mm), sharpen Meckel's cartilage, loss of ceratobranchial, and enlarged angles of ceratohyal (WT: 72.6+/-9.4 degrees ; nf-yb-morphant: 110.0+/-32.5 degrees ). Subsequently, those abnormalities can be rescued after injection with capped nf-yb mRNA. TUNEL assay suggested that large amounts of cell apoptosis appeared in the head region of nf-yb-morphants. Staining with digoxigenin-labeled dlx2a, sox9a, runx2b and col2a1 riboprobes showed that nf-yb-morphants displayed reduced amounts of cranial neural crest cells which are required for mandibular and branchial arches formation. These observations clearly indicate that knockdown of nf-yb translation induced parts of cranial neural crest cells apoptosis, affected cartilages formation and consequently caused reduced-head phenotypes. These findings uncover a novel and unexpected role for NF-YB as a critical modulator of neural crest cell's gene expression governing embryonic cartilage growth.
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Affiliation(s)
- Yau-Hung Chen
- Graduate Institute of Life Sciences, Tamkang University, Tamsui, Taipei County, Taiwan.
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144
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Siefers N, Dang KK, Kumimoto RW, Bynum WE, Tayrose G, Holt BF. Tissue-specific expression patterns of Arabidopsis NF-Y transcription factors suggest potential for extensive combinatorial complexity. PLANT PHYSIOLOGY 2009; 149:625-41. [PMID: 19019982 PMCID: PMC2633833 DOI: 10.1104/pp.108.130591] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 11/12/2008] [Indexed: 05/18/2023]
Abstract
All aspects of plant and animal development are controlled by complex networks of transcription factors. Transcription factors are essential for converting signaling inputs, such as changes in daylength, into complex gene regulatory outputs. While some transcription factors control gene expression by binding to cis-regulatory elements as individual subunits, others function in a combinatorial fashion. How individual subunits of combinatorial transcription factors are spatially and temporally deployed (e.g. expression-level, posttranslational modifications and subcellular localization) has profound effects on their control of gene expression. In the model plant Arabidopsis (Arabidopsis thaliana), we have identified 36 Nuclear Factor Y (NF-Y) transcription factor subunits (10 NF-YA, 13 NF-YB, and 13 NF-YC subunits) that can theoretically combine to form 1,690 unique complexes. Individual plant subunits have functions in flowering time, embryo maturation, and meristem development, but how they combine to control these processes is unknown. To assist in the process of defining unique NF-Y complexes, we have created promoter:beta-glucuronidase fusion lines for all 36 Arabidopsis genes. Here, we show NF-Y expression patterns inferred from these promoter:beta-glucuronidase lines for roots, light- versus dark-grown seedlings, rosettes, and flowers. Additionally, we review the phylogenetic relationships and examine protein alignments for each NF-Y subunit family. The results are discussed with a special emphasis on potential roles for NF-Y subunits in photoperiod-controlled flowering time.
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Affiliation(s)
- Nicholas Siefers
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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145
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Oki K, Inaba N, Kitagawa K, Fujioka S, Kitano H, Fujisawa Y, Kato H, Iwasaki Y. Function of the alpha subunit of rice heterotrimeric G protein in brassinosteroid signaling. PLANT & CELL PHYSIOLOGY 2009; 50:161-72. [PMID: 19036785 DOI: 10.1093/pcp/pcn182] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The alpha subunit of plant heterotrimeric G proteins (Galpha) plays pivotal roles in multiple aspects of development and responses to plant hormones. Recently, several lines of evidence have shown that Galpha participates in brassinosteroid (BR) responses in Arabidopsis and rice plants. In this study, we conducted a comprehensive analysis of the roles of the rice Galpha in the responses to BR using a defective mutant of the Galpha gene, T65d1. Decreased sensitivity to 24-epi-brassinolide (24-epiBL) in the T65d1 mutant was observed in many processes examined, e.g. in the inhibition of root growth and the promotion of coleoptile elongation. The T65d1 mutant also showed similar phenotypes to those of BR-deficient mutants, such as the specifically shortened second internode and the constitutive photomorphogenic growth phenotype under dark conditions. However, a negative feedback effect by 24-epiBL on the expression of BR biosynthetic genes was observed in the T65d1 mutant, and the levels of BR intermediates did not fluctuate in this mutant. To determine the epistatic relationship between the T65d1 mutant and d61-7, a weak allele of a rice BR receptor mutant, the two mutants were crossed. The T65d1/d61-7 double mutant showed no epistasis in the elongation inhibition of the internodes, the internode elongation pattern, the leaf angle and the morphological abnormality of leaf, except for the vertical length of seed and the seed weight. Our results suggest that the rice Galpha affects the BR signaling cascade but the Galpha may not be a signaling molecule in BRI1-meditated perception/transduction.
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Affiliation(s)
- Katsuyuki Oki
- Department of Bioscience, Fukui Prefectural University, Yoshida-gun, Fukui, Japan
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146
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Oki K, Inaba N, Kitano H, Takahashi S, Fujisawa Y, Kato H, Iwasaki Y. Study of novel d1 alleles, defective mutants of the .ALPHA. subunit of heterotrimeric G-protein in rice. Genes Genet Syst 2009; 84:35-42. [DOI: 10.1266/ggs.84.35] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Katsuyuki Oki
- Department of Bioscience, Fukui Prefectural University
| | - Noriko Inaba
- Department of Bioscience, Fukui Prefectural University
| | - Hidemi Kitano
- Bioscience and Biotechnology Center, Nagoya University
| | | | | | - Hisaharu Kato
- Department of Bioscience, Fukui Prefectural University
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147
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Warpeha KM, Gibbons J, Carol A, Slusser J, Tree R, Durham W, Kaufman LS. Adequate phenylalanine synthesis mediated by G protein is critical for protection from UV radiation damage in young etiolated Arabidopsis thaliana seedlings. PLANT, CELL & ENVIRONMENT 2008; 31:1756-1770. [PMID: 18761702 DOI: 10.1111/j.1365-3040.2008.01878.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Etiolated Arabidopsis thaliana seedlings, lacking a functional prephenate dehydratase1 gene (PD1), also lack the ability to synthesize phenylalanine (Phe) and, as a consequence, phenylpropanoid pigments. We find that low doses of ultraviolet (UV)-C (254 nm) are lethal and low doses of UV-B cause severe damage to etiolated pd1 mutants, but not to wild-type (wt) seedlings. Furthermore, exposure to UV-C is lethal to etiolated gcr1 (encoding a putative G protein-coupled receptor in Arabidopsis) mutants and gpa1 (encoding the sole G protein alpha subunit in Arabidopsis) mutants. Addition of Phe to growth media restores wt levels of UV resistance to pd1 mutants. The data indicate that the Arabidopsis G protein-signalling pathway is critical to providing protection from UV, and does so via the activation of PD1, resulting in the synthesis of Phe. Cotyledons of etiolated pd1 mutants have proplastids (compared with etioplasts in wt), less cuticular wax and fewer long-chain fatty acids. Phe-derived pigments do not collect in the epidermal cells of pd1 mutants when seedlings are treated with UV, particularly at the cotyledon tip. Addition of Phe to the growth media restores a wt phenotype to pd1 mutants.
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Affiliation(s)
- Katherine M Warpeha
- Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
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148
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Combier JP, de Billy F, Gamas P, Niebel A, Rivas S. Trans-regulation of the expression of the transcription factor MtHAP2-1 by a uORF controls root nodule development. Genes Dev 2008; 22:1549-59. [PMID: 18519645 DOI: 10.1101/gad.461808] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
MtHAP2-1 is a CCAAT-binding transcription factor from the model legume Medicago truncatula. We previously showed that MtHAP2-1 expression is regulated both spatially and temporally by microRNA169. Here we present a novel regulatory mechanism controlling MtHAP2-1 expression. Alternative splicing of an intron in the MtHAP2-1 5'leader sequence (LS) becomes predominant during the development of root nodules, leading to the production of a small peptide, uORF1p. Our results indicate that binding of uORF1p to MtHAP2-1 5'LS mRNA leads to reduced accumulation of the MtHAP2-1 transcript and may contribute to spatial restriction of MtHAP2-1 expression within the nodule. We propose that miR169 and uORF1p play essential, sequential, and nonredundant roles in regulating MtHAP2-1 expression. Importantly, in contrast to previously described cis-acting uORFs, uORF1p is able to act in trans to down-regulate gene expression. Our work thus contributes to a better understanding of the action of upstream ORFs (uORFs) in the regulation of gene expression.
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Affiliation(s)
- Jean Philippe Combier
- Laboratoire des Interactions Plantes Micro-organismes (LIPM), Centre National de la Recherche Scientifique-Institut National de la Recherche Agronomique UMR 2594/441, F-31320 Castanet Tolosan, France.
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149
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Gookin TE, Kim J, Assmann SM. Whole proteome identification of plant candidate G-protein coupled receptors in Arabidopsis, rice, and poplar: computational prediction and in-vivo protein coupling. Genome Biol 2008; 9:R120. [PMID: 18671868 PMCID: PMC2530877 DOI: 10.1186/gb-2008-9-7-r120] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Revised: 04/19/2008] [Accepted: 07/31/2008] [Indexed: 11/10/2022] Open
Abstract
Computational prediction and in vivo protein coupling experiments identify candidate plant G-protein coupled receptors in Arabidopsis, rice and poplar. Background The classic paradigm of heterotrimeric G-protein signaling describes a heptahelical, membrane-spanning G-protein coupled receptor that physically interacts with an intracellular Gα subunit of the G-protein heterotrimer to transduce signals. G-protein coupled receptors comprise the largest protein superfamily in metazoa and are physiologically important as they sense highly diverse stimuli and play key roles in human disease. The heterotrimeric G-protein signaling mechanism is conserved across metazoa, and also readily identifiable in plants, but the low sequence conservation of G-protein coupled receptors hampers the identification of novel ones. Using diverse computational methods, we performed whole-proteome analyses of the three dominant model plant species, the herbaceous dicot Arabidopsis thaliana (mouse-eared cress), the monocot Oryza sativa (rice), and the woody dicot Populus trichocarpa (poplar), to identify plant protein sequences most likely to be GPCRs. Results Our stringent bioinformatic pipeline allowed the high confidence identification of candidate G-protein coupled receptors within the Arabidopsis, Oryza, and Populus proteomes. We extended these computational results through actual wet-bench experiments where we tested over half of our highest ranking Arabidopsis candidate G-protein coupled receptors for the ability to physically couple with GPA1, the sole Gα in Arabidopsis. We found that seven out of eight tested candidate G-protein coupled receptors do in fact interact with GPA1. We show through G-protein coupled receptor classification and molecular evolutionary analyses that both individual G-protein coupled receptor candidates and candidate G-protein coupled receptor families are conserved across plant species and that, in some cases, this conservation extends to metazoans. Conclusion Our computational and wet-bench results provide the first step toward understanding the diversity, conservation, and functional roles of plant candidate G-protein coupled receptors.
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Affiliation(s)
- Timothy E Gookin
- Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA.
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150
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Trusov Y, Zhang W, Assmann SM, Botella JR. Ggamma1 + Ggamma2 not equal to Gbeta: heterotrimeric G protein Ggamma-deficient mutants do not recapitulate all phenotypes of Gbeta-deficient mutants. PLANT PHYSIOLOGY 2008; 147:636-49. [PMID: 18441222 PMCID: PMC2409028 DOI: 10.1104/pp.108.117655] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 04/22/2008] [Indexed: 05/20/2023]
Abstract
Heterotrimeric G proteins are signaling molecules ubiquitous among all eukaryotes. The Arabidopsis (Arabidopsis thaliana) genome contains one Galpha (GPA1), one Gbeta (AGB1), and two Ggamma subunit (AGG1 and AGG2) genes. The Gbeta requirement of a functional Ggamma subunit for active signaling predicts that a mutant lacking both AGG1 and AGG2 proteins should phenotypically resemble mutants lacking AGB1 in all respects. We previously reported that Gbeta- and Ggamma-deficient mutants coincide during plant pathogen interaction, lateral root development, gravitropic response, and some aspects of seed germination. Here, we report a number of phenotypic discrepancies between Gbeta- and Ggamma-deficient mutants, including the double mutant lacking both Ggamma subunits. While Gbeta-deficient mutants are hypersensitive to abscisic acid inhibition of seed germination and are hyposensitive to abscisic acid inhibition of stomatal opening and guard cell inward K+ currents, none of the available Ggamma-deficient mutants shows any deviation from the wild type in these responses, nor do they show the hypocotyl elongation and hook development defects that are characteristic of Gbeta-deficient mutants. In addition, striking discrepancies were observed in the aerial organs of Gbeta- versus Ggamma-deficient mutants. In fact, none of the distinctive traits observed in Gbeta-deficient mutants (such as reduced size of cotyledons, leaves, flowers, and siliques) is present in any of the Ggamma single and double mutants. Despite the considerable amount of phenotypic overlap between Gbeta- and Ggamma-deficient mutants, confirming the tight relationship between Gbeta and Ggamma subunits in plants, considering the significant differences reported here, we hypothesize the existence of new and as yet unknown elements in the heterotrimeric G protein signaling complex.
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Affiliation(s)
- Yuri Trusov
- Plant Genetic Engineering Laboratory, Department of Botany, School of Integrative Biology, University of Queensland, Brisbane, Queensland 4072, Australia
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