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Kabir AH, Bennetzen JL. Molecular insights into the mutualism that induces iron deficiency tolerance in sorghum inoculated with Trichoderma harzianum. Microbiol Res 2024; 281:127630. [PMID: 38295681 DOI: 10.1016/j.micres.2024.127630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/16/2024]
Abstract
Iron (Fe) deficiency is a common mineral stress in plants, including sorghum. Although the soil fungus Trichoderma harzianum has been shown to mitigate Fe deficiency in some circumstances, neither the range nor mechanism(s) of this process are well understood. In this study, high pH-induced Fe deficiency in sorghum cultivated in pots with natural field soil exhibited a significant decrease in biomass, photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, and Fe-uptake in both the root and shoot. However, the establishment of T. harzianum colonization in roots of Fe-deprived sorghum showed significant improvements in morpho-physiological traits, Fe levels, and redox status. Molecular detection of the fungal ThAOX1 (L-aminoacid oxidase) gene showed the highest colonization of T. harzianum in the root tips of Fe-deficient sorghum, a location thus targeted for further analysis. Expression studies by RNA-seq and qPCR in sorghum root tips revealed a significant upregulation of several genes associated with Fe uptake (SbTOM2), auxin synthesis (SbSAURX15), nicotianamine synthase 3 (SbNAS3), and a phytosiderophore transporter (SbYS1). Also induced was the siderophore synthesis gene (ThSIT1) in T. harzianum, a result supported by biochemical evidence for elevated siderophore and IAA (indole acetic acid) levels in roots. Given the high affinity of fungal siderophore to chelate insoluble Fe3+ ions, it is likely that elevated siderophore released by T. harzianum led to Fe(III)-siderophore complexes in the rhizosphere that were then transported into roots by the induced SbYS1 (yellow-stripe 1) transporter. In addition, the observed induction of several plant peroxidase genes and ABA (abscisic acid) under Fe deficiency after inoculation with T. harzianum may have helped induce tolerance to Fe-deficiency-induced oxidative stress and adaptive responses. This is the first mechanistic explanation for T. harzianum's role in helping alleviate Fe deficiency in sorghum and suggests that biofertilizers using T. harzianum will improve Fe availability to crops in high pH environments.
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Affiliation(s)
- Ahmad H Kabir
- School of Sciences, University of Louisiana at Monroe, LA 71209, USA; Department of Genetics, University of Georgia, Athens, GA 30602, USA.
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Li X, Fu Q, Zhao FX, Wu YQ, Zhang TY, Li ZQ, He JM. GCR1 Positively Regulates UV-B- and Ethylene-Induced Stomatal Closure via Activating GPA1-Dependent ROS and NO Production. Int J Mol Sci 2022; 23:ijms23105512. [PMID: 35628324 PMCID: PMC9141438 DOI: 10.3390/ijms23105512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/07/2022] [Accepted: 05/12/2022] [Indexed: 11/30/2022] Open
Abstract
Heterotrimeric G proteins function as key players in guard cell signaling to many stimuli, including ultraviolet B (UV-B) and ethylene, but whether guard cell G protein signaling is activated by the only one potential G protein-coupled receptor, GCR1, is still unclear. Here, we found that gcr1 null mutants showed defects in UV-B- and ethylene-induced stomatal closure and production of reactive oxygen species (ROS) and nitric oxide (NO) in guard cells, but these defects could be rescued by the application of a Gα activator or overexpression of a constitutively active form of Gα subunit GPA1 (cGPA1). Moreover, the exogenous application of hydrogen peroxide (H2O2) or NO triggered stomatal closure in gcr1 mutants and cGPA1 transgenic plants in the absence or presence of UV-B or ethylene, but exogenous ethylene could not rescue the defect of gcr1 mutants in UV-B-induced stomatal closure, and gcr1 mutants did not affect UV-B-induced ethylene production in Arabidopsis leaves. These results indicate that GCR1 positively controls UV-B- and ethylene-induced stomatal closure by activating GPA1-dependent ROS and NO production in guard cells and that ethylene acts upstream of GCR1 to transduce UV-B guard cell signaling, which establishes the existence of a classic paradigm of G protein signaling in guard cell signaling to UV-B and ethylene.
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Mino M, Tezuka T, Shomura S. The hybrid lethality of interspecific F 1 hybrids of Nicotiana: a clue to understanding hybrid inviability-a major obstacle to wide hybridization and introgression breeding of plants. MOLECULAR BREEDING : NEW STRATEGIES IN PLANT IMPROVEMENT 2022; 42:10. [PMID: 37309322 PMCID: PMC10248639 DOI: 10.1007/s11032-022-01279-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 01/23/2022] [Indexed: 06/14/2023]
Abstract
Reproductive isolation poses a major obstacle to wide hybridization and introgression breeding of plants. Hybrid inviability in the postzygotic isolation barrier inevitably reduces hybrid fitness, consequently causing hindrances in the establishment of novel genotypes from the hybrids among genetically divergent parents. The idea that the plant immune system is involved in the hybrid problem is applicable to the intra- and/or interspecific hybrids of many different taxa. The lethality characteristics and expression profile of genes associated with the hypersensitive response of the hybrids, along with the suppression of causative genes, support the deleterious epistatic interaction of parental NB-LRR protein genes, resulting in aberrant hyper-immunity reactions in the hybrid. Moreover, the cellular, physiological, and biochemical reactions observed in hybrid cells also corroborate this hypothesis. However, the difference in genetic backgrounds of the respective hybrids may contribute to variations in lethality phenotypes among the parental species combinations. The mixed state in parental components of the chaperone complex (HSP90-SGT1-RAR1) in the hybrid may also affect the hybrid inviability. This review article discusses the facts and hypothesis regarding hybrid inviability, alongside the findings of studies on the hybrid lethality of interspecific hybrids of the genus Nicotiana. A possible solution for averting the hybrid problem has also been scrutinized with the aim of improving the wide hybridization and introgression breeding program in plants.
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Affiliation(s)
- Masanobu Mino
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto, 606-8522 Japan
- Present Address: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku Sakai, Osaka, 599-8531 Japan
| | - Takahiro Tezuka
- Present Address: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku Sakai, Osaka, 599-8531 Japan
| | - Sachiko Shomura
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto, 606-8522 Japan
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Brunetti SC, Arseneault MKM, Wright JA, Wang Z, Ehdaeivand MR, Lowden MJ, Rivoal J, Khalil HB, Garg G, Gulick PJ. The stress induced caleosin, RD20/CLO3, acts as a negative regulator of GPA1 in Arabidopsis. PLANT MOLECULAR BIOLOGY 2021; 107:159-175. [PMID: 34599731 DOI: 10.1007/s11103-021-01189-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 09/05/2021] [Indexed: 06/13/2023]
Abstract
KEY MESSAGE A stress induced calcium-binding protein, RD20/CLO3 interacts with the alpha subunit of the heterotrimeric G-protein complex in Arabidopsis and affects etiolation and leaf morphology. Heterotrimeric G proteins and calcium signaling have both been shown to play a role in the response to environmental abiotic stress in plants; however, the interaction between calcium-binding proteins and G-protein signaling molecules remains elusive. We investigated the interaction between the alpha subunit of the heterotrimeric G-protein complex, GPA1, of Arabidopsis thaliana with the calcium-binding protein, the caleosin RD20/CLO3, a gene strongly induced by drought, salt and abscisic acid. The proteins were found to interact in vivo by bimolecular fluorescent complementation (BiFC); the interaction was localized to the endoplasmic reticulum and to oil bodies within the cell. The constitutively GTP-bound GPA1 (GPA1QL) also interacts with RD20/CLO3 as well as its EF-hand mutant variations and these interactions are localized to the plasma membrane. The N-terminal portion of RD20/CLO3 was found to be responsible for the interaction with GPA1 and GPA1QL using both BiFC and yeast two-hybrid assays. RD20/CLO3 contains a single calcium-binding EF-hand in the N-terminal portion of the protein; disruption of the calcium-binding capacity of the protein obliterates interaction with GPA1 in in vivo assays and decreases the interaction between the caleosin and the constitutively active GPA1QL. Analysis of rd20/clo3 mutants shows that RD20/CLO3 plays a key role in the signaling pathway controlling hypocotyl length in dark grown seedlings and in leaf morphology. Our findings indicate a novel role for RD20/CLO3 as a negative regulator of GPA1.
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Affiliation(s)
- Sabrina C Brunetti
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
| | - Michelle K M Arseneault
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
| | - Justin A Wright
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
| | - Zhejun Wang
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
| | | | - Michael J Lowden
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
| | - Jean Rivoal
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada
| | - Hala B Khalil
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
- Department of Genetics, Faculty of Agriculture, Ain-Shams University, Shoubra El-khema, Cairo, Egypt
| | - Gajra Garg
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada
- Department of Biotechnology & Microbiology, Mahatma Jyoti Rao Phoole University, Jaipur, Rajasthan, India
| | - Patrick J Gulick
- Department of Biology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada.
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Zhai X, Jia M, Chen L, Zheng CJ, Rahman K, Han T, Qin LP. The regulatory mechanism of fungal elicitor-induced secondary metabolite biosynthesis in medical plants. Crit Rev Microbiol 2016; 43:238-261. [PMID: 27936989 DOI: 10.1080/1040841x.2016.1201041] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A wide range of external stress stimuli trigger plant cells to undergo complex network of reactions that ultimately lead to the synthesis and accumulation of secondary metabolites. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Throughout evolution, endophytic fungi, an important constituent in the environment of medicinal plants, have known to form long-term stable and mutually beneficial symbiosis with medicinal plants. The endophytic fungal elicitor can rapidly and specifically induce the expression of specific genes in medicinal plants which can result in the activation of a series of specific secondary metabolic pathways resulting in the significant accumulation of active ingredients. Here we summarize the progress made on the mechanisms of fungal elicitor including elicitor signal recognition, signal transduction, gene expression and activation of the key enzymes and its application. This review provides guidance on studies which may be conducted to promote the efficient synthesis and accumulation of active ingredients by the endogenous fungal elicitor in medicinal plant cells, and provides new ideas and methods of studying the regulation of secondary metabolism in medicinal plants.
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Affiliation(s)
- Xin Zhai
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
| | - Min Jia
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
| | - Ling Chen
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
| | - Cheng-Jian Zheng
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
| | - Khalid Rahman
- b Department of Physiological Biochemistry, Faculty of Science, School of Pharmacy and Biomolecular Sciences , Liverpool John Moores University , Liverpool , UK
| | - Ting Han
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
| | - Lu-Ping Qin
- a Department of Pharmacognosy, School of Pharmacy , Second Military Medical University , Shanghai , China
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Zhao X, Wang J, Yuan J, Wang XL, Zhao QP, Kong PT, Zhang X. NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) is essential for salicylic acid-induced root waving in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2015; 207:211-224. [PMID: 25690466 DOI: 10.1111/nph.13327] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/10/2015] [Indexed: 05/07/2023]
Abstract
Root waving responses have been attributed to both environmental and genetics factors, but the potential inducers and transducers of root waving remain elusive. Thus, the identification of novel signal elements related to root waving is an intriguing field of research. Genetic, physiological, cytological, live cell imaging, and pharmacological approaches provide strong evidence for the involvement of Arabidopsis thaliana NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) in salicylic acid (SA)-induced root waving. SA specially induced root waving, with an overall decrease in root elongation in A. thaliana, and this SA-induced response was disrupted in the Atnoa1 mutant, as well as in nonexpresser of pathogenesis-related genes 1 (npr1), which is defective in SA-mediated plant defense signal transduction, but not in npr3/4 single and double mutants. The expression assays revealed that the abundance of AtNOA1 was significantly increased by application of SA. Genetic and pharmacological analyses showed that SA-induced root waving involved an AtNOA1-dependent Ca(2+) signal transduction pathway, and PIN-FORMED2 (PIN2) -based polar auxin transport possibly plays a crucial role in this process. Our work suggests that SA signaling through NPR1 and AtNOA1 is involved in the control of root waving, which provides new insights into the mechanisms that control root growth behavior on a hard agar surface.
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Affiliation(s)
- Xiang Zhao
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Jin Wang
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Jing Yuan
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Xi-Li Wang
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Qing-Ping Zhao
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Pei-Tao Kong
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Xiao Zhang
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
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Shi C, Qi C, Ren H, Huang A, Hei S, She X. Ethylene mediates brassinosteroid-induced stomatal closure via Gα protein-activated hydrogen peroxide and nitric oxide production in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:280-301. [PMID: 25754244 DOI: 10.1111/tpj.12815] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 02/14/2015] [Accepted: 02/23/2015] [Indexed: 05/07/2023]
Abstract
Brassinosteroids (BRs) are essential for plant growth and development; however, whether and how they promote stomatal closure is not fully clear. In this study, we report that 24-epibrassinolide (EBR), a bioactive BR, induces stomatal closure in Arabidopsis (Arabidopsis thaliana) by triggering a signal transduction pathway including ethylene synthesis, the activation of Gα protein, and hydrogen peroxide (H(2)O(2)) and nitric oxide (NO) production. EBR initiated a marked rise in ethylene, H(2)O(2) and NO levels, necessary for stomatal closure in the wild type. These effects were abolished in mutant bri1-301, and EBR failed to close the stomata of gpa1 mutants. Next, we found that both ethylene and Gα mediate the inductive effects of EBR on H(2)O(2) and NO production. EBR-triggered H(2)O(2) and NO accumulation were canceled in the etr1 and gpa1 mutants, but were strengthened in the eto1-1 mutant and the cGα line (constitutively overexpressing the G protein α-subunit AtGPA1). Exogenously applied H(2)O(2) or sodium nitroprusside (SNP) rescued the defects of etr1-3 and gpa1 or etr1 and gpa1 mutants in EBR-induced stomatal closure, whereas the stomata of eto1-1/AtrbohF and cGα/AtrbohF or eto1-1/nia1-2 and cGα/nia1-2 constructs had an analogous response to H(2)O(2) or SNP as those of AtrbohF or Nia1-2 mutants. Moreover, we provided evidence that Gα plays an important role in the responses of guard cells to ethylene. Gα activator CTX largely restored the lesion of the etr1-3 mutant, but ethylene precursor ACC failed to rescue the defects of gpa1 mutants in EBR-induced stomatal closure. Lastly, we demonstrated that Gα-activated H(2)O(2) production is required for NO synthesis. EBR failed to induce NO synthesis in mutant AtrbohF, but it led to H(2)O(2) production in mutant Nia1-2. Exogenously applied SNP rescued the defect of AtrbohF in EBR-induced stomatal closure, but H(2)O(2) did not reverse the lesion of EBR-induced stomatal closure in Nia1-2. Together, our results strongly suggest a signaling pathway in which EBR induces ethylene synthesis, thereby activating Gα, and then promotes AtrbohF-dependent H(2)O(2) production and subsequent Nia1-catalyzed NO accumulation, and finally closes stomata.
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Affiliation(s)
- Chenyu Shi
- School of Life Sciences, Shaanxi Normal University, Xi'an, 710062, China; School of Chemistry and Bioengineering, Hechi University, Yizhou, 546300, China
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Hao LH, Wang WX, Chen C, Wang YF, Liu T, Li X, Shang ZL. Extracellular ATP promotes stomatal opening of Arabidopsis thaliana through heterotrimeric G protein α subunit and reactive oxygen species. MOLECULAR PLANT 2012; 5:852-64. [PMID: 22138967 DOI: 10.1093/mp/ssr095] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In recent years, adenosine tri-phosphate (ATP) has been reported to exist in apoplasts of plant cells as a signal molecule. Extracellular ATP (eATP) plays important roles in plant growth, development, and stress tolerance. Here, extracellular ATP was found to promote stomatal opening of Arabidopsis thaliana in light and darkness. ADP, GTP, and weakly hydrolyzable ATP analogs (ATPγS, Bz-ATP, and 2meATP) showed similar effects, whereas AMP and adenosine did not affect stomatal movement. Apyrase inhibited stomatal opening. ATP-promoted stomatal opening was blocked by an NADPH oxidase inhibitor (diphenylene iodonium) or deoxidizer (dithiothreitol), and was impaired in null mutant of NADPH oxidase (atrbohD/F). Added ATP triggered ROS generation in guard cells via NADPH oxidase. ATP also induced Ca(2+) influx and H(+) efflux in guard cells. In atrbohD/F, ATP-induced ion flux was strongly suppressed. In null mutants of the heterotrimeric G protein α subunit, ATP-promoted stomatal opening, cytoplasmic ROS generation, Ca(2+) influx, and H(+) efflux were all suppressed. These results indicated that eATP-promoted stomatal opening possibly involves the heterotrimeric G protein, ROS, cytosolic Ca(2+), and plasma membrane H(+)-ATPase.
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Affiliation(s)
- Li-Hua Hao
- Key Laboratory of Molecular and Cell Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, PR China
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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: 21] [Impact Index Per Article: 1.8] [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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Hubbard KE, Siegel RS, Valerio G, Brandt B, Schroeder JI. Abscisic acid and CO2 signalling via calcium sensitivity priming in guard cells, new CDPK mutant phenotypes and a method for improved resolution of stomatal stimulus-response analyses. ANNALS OF BOTANY 2012; 109:5-17. [PMID: 21994053 PMCID: PMC3241576 DOI: 10.1093/aob/mcr252] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 08/23/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Stomatal guard cells are the regulators of gas exchange between plants and the atmosphere. Ca(2+)-dependent and Ca(2+)-independent mechanisms function in these responses. Key stomatal regulation mechanisms, including plasma membrane and vacuolar ion channels have been identified and are regulated by the free cytosolic Ca(2+) concentration ([Ca(2+)](cyt)). SCOPE Here we show that CO(2)-induced stomatal closing is strongly impaired under conditions that prevent intracellular Ca(2+) elevations. Moreover, Ca(2+) oscillation-induced stomatal closing is partially impaired in knock-out mutations in several guard cell-expressed Ca(2+)-dependent protein kinases (CDPKs) here, including the cpk4cpk11 double and cpk10 mutants; however, abscisic acid-regulated stomatal movements remain relatively intact in the cpk4cpk11 and cpk10 mutants. We further discuss diverse studies of Ca(2+) signalling in guard cells, discuss apparent peculiarities, and pose novel open questions. The recently proposed Ca(2+) sensitivity priming model could account for many of the findings in the field. Recent research shows that the stomatal closing stimuli abscisic acid and CO(2) enhance the sensitivity of stomatal closing mechanisms to intracellular Ca(2+), which has been termed 'calcium sensitivity priming'. The genome of the reference plant Arabidopsis thaliana encodes for over 250 Ca(2+)-sensing proteins, giving rise to the question, how can specificity in Ca(2+) responses be achieved? Calcium sensitivity priming could provide a key mechanism contributing to specificity in eukaryotic Ca(2+) signal transduction, a topic of central interest in cell signalling research. In this article we further propose an individual stomatal tracking method for improved analyses of stimulus-regulated stomatal movements in Arabidopsis guard cells that reduces noise and increases fidelity in stimulus-regulated stomatal aperture responses ( Box 1). This method is recommended for stomatal response research, in parallel to previously adopted blind analyses, due to the relatively small and diverse sizes of stomatal apertures in the reference plant Arabidopsis thaliana.
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Affiliation(s)
| | | | | | | | - Julian I. Schroeder
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA
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Faurie B, Cluzet S, Mérillon JM. Implication of signaling pathways involving calcium, phosphorylation and active oxygen species in methyl jasmonate-induced defense responses in grapevine cell cultures. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:1863-1877. [PMID: 19631405 DOI: 10.1016/j.jplph.2009.05.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 05/22/2009] [Accepted: 05/22/2009] [Indexed: 05/28/2023]
Abstract
Perception of elicitors triggers plant defense responses via various early signal transduction pathways. Methyl jasmonate (MeJA) stimulates defense responses in grapevine (Vitis vinifera). We investigated the involvement of various partners (calcium, ROS, reversible phosphorylation) in MeJA-induced responses by using a pharmacological approach. We used specific calcium channel effectors and inhibitors of serine/threonine phosphatases, superoxide dismutase and NAD(P)H oxidase and investigated production of stilbenes (resveratrol and its glucoside, piceid, the major form), which are the grapevine phytoalexins. RNA accumulation of two genes encoding enzymes involved in stilbene synthesis (PAL and STS), three genes encoding pathogenesis-related proteins (CHIT4C, PIN and GLU) and one gene encoding an enzyme producing jasmonates (LOX) were also assessed. Calcium and its origin seemed to play a major role in MeJA-induced grapevine defense responses. Phytoalexin production was strongly affected if calcium from the influx plasma membrane was inhibited, whereas calcium from the intracellular compartments did not seem to be involved. ROS production seemed to interfere with MeJA-stimulated defense responses, and protein phosphorylation/dephosphorylation events also played a direct role.
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Affiliation(s)
- Bertrand Faurie
- Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, UFR Sciences Pharmaceutiques, Université de Bordeaux, ISVV Bordeaux-Aquitaine-CS 50008-210, Chemin de Leysotte, 33882 Villenave d'Ornon Cedex, France
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Transduction mechanisms of photoreceptor signals in plant cells. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2009. [DOI: 10.1016/j.jphotochemrev.2009.04.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Stockman G, Boland R. Integration of Plasma Membrane and Nuclear Signaling in Elicitor Regulation of Plant Secondary Metabolism. Nat Prod Commun 2008. [DOI: 10.1177/1934578x0800300803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The plant kingdom represents a valuable source of natural products of commercial interest. These compounds, named secondary metabolites, are not essential for the survival of plants, but confer them some advantages that allow adaptation to changes in their environment. Nevertheless, yields of secondary metabolites are low for commercial purposes, so it has become important to design strategies for increasing their production. Plants manage to adapt to physical changes in their environment, defending themselves against pathogen attack or herbivore wounding. Such aggressive stimuli, also known as elicitors, initiate signaling metabolic cascades that induce accumulation of certain secondary metabolites. Progress has been recently achieved in the understanding of signaling events originating from elicitation and related transcriptional regulation. These advances will allow maneuvering expression of key enzymes implicated in biosynthetic pathways of secondary metabolites, thereby enhancing their accumulation.
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Affiliation(s)
- Gastón Stockman
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Buenos Aires 8000, Argentina
| | - Ricardo Boland
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Buenos Aires 8000, Argentina
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14
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Heinze M, Steighardt J, Gesell A, Schwartze W, Roos W. Regulatory interaction of the Galpha protein with phospholipase A2 in the plasma membrane of Eschscholzia californica. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:1041-1051. [PMID: 17916111 DOI: 10.1111/j.1365-313x.2007.03300.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Plant heterotrimeric G-proteins are involved in a variety of signaling pathways, though only one alpha and a few betagamma isoforms of their subunits exist. In isolated plasma membranes of California poppy (Eschscholzia californica), the plant-specific Galpha subunit was isolated and identified immunologically and by homology of the cloned gene with that of several plants. In the same membrane, phospholipase A(2) (PLA(2)) was activated by yeast elicitor only if GTPgammaS (an activator of Galpha) was present. From the cholate-solubilized membrane proteins, PLA(2) was co-precipitated together with Galpha by a polyclonal antiserum raised against the recombinant Galpha. In this immunoprecipitate and in the plasma membrane (but not in the Galpha-free supernatant) PLA(2) was stimulated by GTPgammaS. Plasma membranes and immunoprecipitates obtained from antisense transformants with a low Galpha content allowed no such stimulation. An antiserum raised against the C-terminus (which in animal Galphas is located near the target coupling site) precipitated Galpha without any PLA(2) activity. Using non-denaturing PAGE, complexes of solubilized plasma membrane proteins were visualized that contained Galpha plus PLA(2) activity and dissociated at pH 9.5. At this pH, PLA(2) was no longer stimulated by GTPgammaS. It is concluded that a distinct fraction of the plasma membrane-bound PLA(2) exists in a detergent-resistant complex with Galpha that can be dissociated at pH 9.5. This complex allows the Galpha-mediated activation of PLA(2).
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Affiliation(s)
- Michael Heinze
- Department of Molecular Cell Biology, Institute of Pharmaceutical Biology and Pharmacology, Martin-Luther-University, Kurt-Mothes-Strasse 3, 06120 Halle, Germany
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15
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Abstract
Heterotrimeric G-protein complexes couple extracellular signals via cell surface receptors to downstream enzymes called effectors. Heterotrimeric G-protein complexes, together with their cognate receptors and effectors, operate at the apex of signal transduction. In plants, the number of G-protein complex components is dramatically less than in other multicellular eukaryotes. An understanding of how multiple signals propagate transduction through the G-protein node can be found in the unique structural and kinetic properties of the plant heterotrimeric G-protein complex. This review addresses these unique features and speculates on why the repertoire of G-protein signaling elements is dramatically simpler than that in all other multicellular eukaryotes.
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Affiliation(s)
- Brenda R S Temple
- R. L. Juliano Structural Bioinformatics Core Facility, Departments of Biology and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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16
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Wu Y, Xu X, Li S, Liu T, Ma L, Shang Z. Heterotrimeric G-protein participation in Arabidopsis pollen germination through modulation of a plasmamembrane hyperpolarization-activated Ca2+-permeable channel. THE NEW PHYTOLOGIST 2007; 176:550-559. [PMID: 17953540 DOI: 10.1111/j.1469-8137.2007.02214.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The role of heterotrimeric G proteins in pollen germination and tube growth was investigated using Arabidopsis thaliana plants in which the gene (GPA) encoding the G-protein a subunit (Galpha) was null or overexpressed. Pollen germination, free cytosolic calcium concentration ([Ca(2+)](cyt)) and Ca(2+) channel activity in the plasma membrane (PM) of pollen cells were investigated. Results showed that, compared with pollen grains of the wild type (ecotype Wassilewskija, ws), in vitro germinated pollen of Galpha null mutants (gpa1-1 and gpa1-2) had lower germination percentages and shorter pollen tubes, while pollen from Galpha overexpression lines (wGalpha and cGalpha) had higher germination percentages and longer pollen tubes. Compared with ws pollen cells, [Ca(2+)](cyt) was lower in gpa1-1 and gpa1-2 and higher in wGalpha and cGalpha. In whole-cell patch clamp recordings, a hyperpolarization-activated Ca(2+)-permeable conductance was identified in the PM of pollen protoplasts. The conductance was suppressed by trivalent cations but insensitive to organic blockers; its permeability to divalent cations was Ba(2+) > Ca(2+) > Mg(2+) > Sr(2+) > Mn(2+). The activity of the Ca(2+)-permeable channel conductance was down-regulated in pollen protoplasts of gpa1-1 and gpa1-2, and up-regulated in wGalpha and cGalpha. The results suggest that Galpha may participate in pollen germination through modulation of the hyperpolarization-activated Ca(2+) channel in the PM of pollen cells.
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Affiliation(s)
- Yansheng Wu
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
| | - Xiaodong Xu
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
| | - Sujuan Li
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
| | - Ting Liu
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
| | - Ligeng Ma
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
| | - Zhonglin Shang
- College of Life Science, Hebei Normal University, Shijiazhuang 050016, China
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17
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Wang HX, Weerasinghe RR, Perdue TD, Cakmakci NG, Taylor JP, Marzluff WF, Jones AM. A Golgi-localized hexose transporter is involved in heterotrimeric G protein-mediated early development in Arabidopsis. Mol Biol Cell 2006; 17:4257-69. [PMID: 16855027 PMCID: PMC1635373 DOI: 10.1091/mbc.e06-01-0046] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 07/03/2006] [Accepted: 07/12/2006] [Indexed: 01/08/2023] Open
Abstract
Signal transduction involving heterotrimeric G proteins is universal among fungi, animals, and plants. In plants and fungi, the best understood function for the G protein complex is its modulation of cell proliferation and one of several important signals that are known to modulate the rate at which these cells proliferate is D-glucose. Arabidopsis thaliana seedlings lacking the beta subunit (AGB1) of the G protein complex have altered cell division in the hypocotyl and are D-glucose hypersensitive. With the aim to discover new elements in G protein signaling, we screened for gain-of-function suppressors of altered cell proliferation during early development in the agb1-2 mutant background. One agb1-2-dependent suppressor, designated sgb1-1(D) for suppressor of G protein beta1 (agb1-2), restored to wild type the altered cell division in the hypocotyl and sugar hypersensitivity of the agb1-2 mutant. Consistent with AGB1 localization, SGB1 is found at the highest steady-state level in tissues with active cell division, and this level increases in hypocotyls when grown on D-glucose and sucrose. SGB1 is shown here to be a Golgi-localized hexose transporter and acts genetically with AGB1 in early seedling development.
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Affiliation(s)
| | | | | | | | | | - William F. Marzluff
- Departments of *Biology
- Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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18
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Abstract
Plants, like animals, use signal transduction pathways based on heterotrimeric guanine nucleotide-binding proteins (G proteins) to regulate many aspects of development and cell signaling. Some components of G protein signaling are highly conserved between plants and animals and some are not. This Viewpoint compares key aspects of G protein signal transduction in plants and animals and describes the current knowledge of this system in plants, the questions that still await exploration, and the value of research on plant G proteins to scientists who do not study plants. Pathways in Science's Signal Transduction Knowledge Environment Connections Maps database provide details about the emerging roles of G proteins in several cellular processes of plants.
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Affiliation(s)
- Sarah M Assmann
- Biology Department, Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802, USA.
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19
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Choi MS, Kim MC, Yoo JH, Moon BC, Koo SC, Park BO, Lee JH, Koo YD, Han HJ, Lee SY, Chung WS, Lim CO, Cho MJ. Isolation of a calmodulin-binding transcription factor from rice (Oryza sativa L.). J Biol Chem 2005; 280:40820-31. [PMID: 16192280 DOI: 10.1074/jbc.m504616200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) regulates diverse cellular functions by modulating the activities of a variety of enzymes and proteins. However, direct modulation of transcription factors by CaM has been poorly understood. In this study, we isolated a putative transcription factor by screening a rice cDNA expression library by using CaM:horse-radish peroxidase as a probe. This factor, which we have designated OsCBT (Oryza sativa CaM-binding transcription factor), has structural features similar to Arabidopsis AtSRs/AtCAMTAs and encodes a 103-kDa protein because it contains a CG-1 homology DNA-binding domain, three ankyrin repeats, a putative transcriptional activation domain, and five putative CaM-binding motifs. By using a gel overlay assay, gel mobility shift assays, and site-directed mutagenesis, we showed that OsCBT has two different types of functional CaM-binding domains, an IQ motif, and a Ca(2+)-dependent motif. To determine the DNA binding specificity of OsCBT, we employed a random binding site selection method. This analysis showed that OsCBT preferentially binds to the sequence 5'-TWCG(C/T)GTKKKKTKCG-3' (W and K represent A or C and T or G, respectively). OsCBT was able to bind this sequence and activate beta-glucuronidase reporter gene expression driven by a minimal promoter containing tandem repeats of these sequences in Arabidopsis leaf protoplasts. Green fluorescent protein fusions of two putative nuclear localization signals of OsCBT, a bipartite and a SV40 type, were predominantly localized in the nucleus. Most interestingly, the transcriptional activation mediated by OsCBT was inhibited by co-transfection with a CaM gene. Taken together, our results suggest that OsCBT is a transcription activator modulated by CaM.
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Affiliation(s)
- Man Soo Choi
- Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
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20
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Zhao J, Davis LC, Verpoorte R. Elicitor signal transduction leading to production of plant secondary metabolites. Biotechnol Adv 2005; 23:283-333. [PMID: 15848039 DOI: 10.1016/j.biotechadv.2005.01.003] [Citation(s) in RCA: 868] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2004] [Revised: 01/27/2005] [Accepted: 01/31/2005] [Indexed: 11/30/2022]
Abstract
Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and other industrial materials. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Understanding signal transduction paths underlying elicitor-induced production of secondary metabolites is important for optimizing their commercial production. This paper summarizes progress made on several aspects of elicitor signal transduction leading to production of plant secondary metabolites, including: elicitor signal perception by various receptors of plants; avirulence determinants and corresponding plant R proteins; heterotrimeric and small GTP binding proteins; ion fluxes, especially Ca2+ influx, and Ca2+ signaling; medium alkalinization and cytoplasmic acidification; oxidative burst and reactive oxygen species; inositol trisphosphates and cyclic nucleotides (cAMP and cGMP); salicylic acid and nitric oxide; jasmonate, ethylene, and abscisic acid signaling; oxylipin signals such as allene oxide synthase-dependent jasmonate and hydroperoxide lyase-dependent C12 and C6 volatiles; as well as other lipid messengers such as lysophosphatidylcholine, phosphatidic acid, and diacylglycerol. All these signal components are employed directly or indirectly by elicitors for induction of plant secondary metabolite accumulation. Cross-talk between different signaling pathways is very common in plant defense response, thus the cross-talk amongst these signaling pathways, such as elicitor and jasmonate, jasmonate and ethylene, and each of these with reactive oxygen species, is discussed separately. This review also highlights the integration of multiple signaling pathways into or by transcription factors, as well as the linkage of the above signal components in elicitor signaling network through protein phosphorylation and dephosphorylation. Some perspectives on elicitor signal transduction and plant secondary metabolism at the transcriptome and metabolome levels are also presented.
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Affiliation(s)
- Jian Zhao
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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21
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Oki K, Fujisawa Y, Kato H, Iwasaki Y. Study of the Constitutively Active Form of the α Subunit of Rice Heterotrimeric G Proteins. ACTA ACUST UNITED AC 2005; 46:381-6. [PMID: 15695461 DOI: 10.1093/pcp/pci036] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We used site-directed mutagenesis to engineer two constitutively active forms of the alpha subunit of a rice heterotrimeric G protein. The recombinant proteins produced from these novel cDNAs had GTP-binding activity but no GTPase activity. A chimeric gene for a constitutively active form of the alpha subunit was introduced into the rice mutant d1, which is defective for the alpha-subunit gene. All the transformants essentially showed a wild-type phenotype compared with normal cultivars, although seed sizes were substantially increased and internode lengths also showed some increase.
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Affiliation(s)
- Katsuyuki Oki
- Fukui Prefectural University, Faculty of Bioscience, Kenjyojima, Matsuoka-cho, Yoshida-gun, Fukui, 910-1195 Japan
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22
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Jones AM, Assmann SM. Plants: the latest model system for G-protein research. EMBO Rep 2005; 5:572-8. [PMID: 15170476 PMCID: PMC1299082 DOI: 10.1038/sj.embor.7400174] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Accepted: 04/28/2004] [Indexed: 01/03/2023] Open
Abstract
In humans, heterotrimeric G proteins couple stimulus perception by G-protein-coupled receptors (GPCRs) with numerous downstream effectors. By contrast, despite great complexity in their signal-transduction attributes, plants have a simpler repertoire of G-signalling components. Nonetheless, recent studies on Arabidopsis thaliana have shown the importance of plant G-protein signalling in such fundamental processes as cell proliferation, hormone perception and ion-channel regulation.
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Affiliation(s)
- Alan M. Jones
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Tel: +1 919 962 6932; Fax: +1 919 962 1625;
| | - Sarah M. Assmann
- Biology Department, Penn State University, University Park, Pennsylvania 16802-5301, USA
- Tel: +1 814 863 9579; Fax: +1 814 865 9131;
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23
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Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) composed of Galpha, Gbeta, and Ggamma subunits are important transducers of hormonal signals in organisms as evolutionarily distant as plants and humans. The genomes of diploid angiosperms, such as that of the model species Arabidopsis thaliana, encode only single canonical Galpha and Gbeta subunits, only two identified Ggamma subunits, and just one regulator of G protein signaling (RGS) protein. However, a wide range of processes-including seed germination, shoot and root growth, and stomatal regulation-are altered in Arabidopsis and rice plants with mutations in G protein components. Such mutants exhibit altered responsiveness to a number of plant hormones, including gibberellins, brassinosteroids, abscisic acid, and auxin. This review describes possible mechanisms by which such pleiotropic effects are generated and considers possible explanations for why G protein component mutations in plants fail to be lethal. A possible role of G protein signaling in the control of phenotypic plasticity, a hallmark of plant growth, is also discussed.
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24
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Chen YL, Huang R, Xiao YM, Lü P, Chen J, Wang XC. Extracellular calmodulin-induced stomatal closure is mediated by heterotrimeric G protein and H2O2. PLANT PHYSIOLOGY 2004; 136:4096-103. [PMID: 15557100 PMCID: PMC535840 DOI: 10.1104/pp.104.047837] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 09/20/2004] [Accepted: 09/27/2004] [Indexed: 05/12/2023]
Abstract
Extracellular calmodulin (ExtCaM) exerts multiple functions in animals and plants, but the mode of ExtCaM action is not well understood. In this paper, we provide evidence that ExtCaM stimulates a cascade of intracellular signaling events to regulate stomatal movement. Analysis of the changes of cytosolic free Ca2+ ([Ca2+]cyt) and H2O2 in Vicia faba guard cells combined with epidermal strip bioassay suggests that ExtCaM induces an increase in both H2O2 levels and [Ca2+]cyt, leading to a reduction in stomatal aperture. Pharmacological studies implicate heterotrimeric G protein in transmitting the ExtCaM signal, acting upstream of [Ca2+]cyt elevation, and generating H2O2 in guard cell responses. To further test the role of heterotrimeric G protein in ExtCaM signaling in stomatal closure, we checked guard cell responses in the Arabidopsis (Arabidopsis thaliana) Galpha-subunit-null gpa1 mutants and cGalpha overexpression lines. We found that gpa1 mutants were insensitive to ExtCaM stimulation of stomatal closure, whereas cGalpha overexpression enhanced the guard cell response to ExtCaM. Furthermore, gpa1 mutants are impaired in ExtCaM induction of H2O2 generation in guard cells. Taken together, our results strongly suggest that ExtCaM activates an intracellular signaling pathway involving activation of a heterotrimeric G protein, H2O2 generation, and changes in [Ca2+]cyt in the regulation of stomatal movements.
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Affiliation(s)
- Yu-Ling Chen
- National Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, China
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25
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Lee HY, Bahn SC, Shin JS, Hwang I, Back K, Doelling JH, Ryu SB. Multiple forms of secretory phospholipase A2 in plants. Prog Lipid Res 2004; 44:52-67. [PMID: 15748654 DOI: 10.1016/j.plipres.2004.10.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/01/2004] [Accepted: 10/07/2004] [Indexed: 11/26/2022]
Abstract
Multiple secretory phospholipase A2 (sPLA2) genes have been identified in plants and encode isoforms with distinct regulatory and catalytic properties. Elucidation of this genetic and biochemical heterogeneity has provided important clues to the regulation and function of the individual enzymes. An increasing body of evidence shows that their lipid products, lysophospholipids and free fatty acids, mediate a variety of cellular responses, including plant growth, development, and responses to stress and defense. This review discusses the newly-acquired information on plant sPLA2s including the molecular and biochemical characteristics, and signaling functions of each isoform.
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Affiliation(s)
- Hyoung Yool Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
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26
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Booker FL, Burkey KO, Overmyer K, Jones AM. Differential responses of G-protein Arabidopsis thaliana mutants to ozone. THE NEW PHYTOLOGIST 2004; 162:633-641. [PMID: 33873772 DOI: 10.1111/j.1469-8137.2004.01081.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Ground-level ozone (O3 ) curtails agricultural production in many regions worldwide. However, the etiology of O3 toxicity remains unclear. Activated oxygen species appear to inflict biochemical lesions and propagate defense responses that compound plant injury. Because some plant defense responses involve membrane-delimited GTPases (G proteins), we evaluated the O3 sensitivity of Arabidopsis mutants altered in the heterotrimeric G-protein pathway. • Eight genotypes were treated with a range of O3 concentrations (0, 100, 175 and 250 nmol mol-1 ) for 13 d in controlled environment chambers. • After treatment with O3 , the epinasty typically observed for wild type leaves did not occur in mutant plants lacking the alpha subunit of the G-protein complex (gpa1). O3 -induced suppression of leaf chlorophyll levels and leaf mass per unit leaf area were less for gpa1 mutants and were not due to differences in O3 flux. • There was a positive correlation between the lack of a G-protein alpha subunit and decreased O3 sensitivity. Our results suggest that a heterotrimeric G-protein is critically involved in the expression of O3 effects in plants.
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Affiliation(s)
- Fitzgerald L Booker
- U.S. Department of Agriculture, Agricultural Research Service, Air Quality - Plant Growth and Development Unit, and Department of Crop Science, North Carolina State University, 3908 Inwood Road, Raleigh, NC 26703 USA
| | - Kent O Burkey
- U.S. Department of Agriculture, Agricultural Research Service, Air Quality - Plant Growth and Development Unit, and Department of Crop Science, North Carolina State University, 3908 Inwood Road, Raleigh, NC 26703 USA
| | - Kirk Overmyer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alan M Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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27
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Nanjo Y, Asatsuma S, Itoh K, Hori H, Mitsui T, Fujisawa Y. Posttranscriptional regulation of alpha-amylase II-4 expression by gibberellin in germinating rice seeds. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2004; 42:477-484. [PMID: 15246060 DOI: 10.1016/j.plaphy.2004.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Accepted: 04/15/2004] [Indexed: 05/24/2023]
Abstract
Hormonal regulation of expression of alpha-amylase II-4 that lacks the gibberellin-response cis-element (GARE) in the promoter region of the gene was studied in germinating rice (Oryza sativa L.) seeds. Temporal and spatial expression of alpha-amylase II-4 in the aleurone layer were essentially identical to those of alpha-amylase I-1 whose gene contains GARE, although these were distinguishable in the embryo tissues at the early stage of germination. The gibberellin-responsible expression of alpha-amylase II-4 was also similar to that of alpha-amylase I-1. However, the level of alpha-amylase II-4 mRNA was not increased by gibberellin, indicating that the transcriptional enhancement of alpha-amylase II-4 expression did not occur in the aleurone. Gibberellin stimulated the accumulation of 45Ca2+ into the intracellular secretory membrane system. In addition, several inhibitors for Ca2+ signaling, such as EGTA, neomycin, ruthenium red (RuR), and W-7 prevented the gibberellin-induced expression of alpha-amylase II-4 effectively. While the gibberellin-induced expression of alpha-amylase II-4 occurred normally in the aleurone layer of a rice dwarf mutant d1 which is defective in the alpha subunit of the heterotrimeric G protein. Based on these results, it was concluded that the posttranscriptional regulation of alpha-amylase II-4 expression by gibberellin operates in the aleurone layer of germinating rice seed, which is mediated by Ca2+ but not the G protein.
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Affiliation(s)
- Yohei Nanjo
- Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
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28
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Miles GP, Samuel MA, Jones AM, Ellis BE. Mastoparan rapidly activates plant MAP kinase signaling independent of heterotrimeric G proteins. PLANT PHYSIOLOGY 2004; 134:1332-6. [PMID: 15084727 PMCID: PMC419810 DOI: 10.1104/pp.103.037275] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Revised: 12/30/2003] [Accepted: 12/30/2003] [Indexed: 05/19/2023]
Affiliation(s)
- Godfrey P Miles
- Biotechnology Laboratory, Agricultural Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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29
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Zhao J, Guo Y, Fujita K, Sakai K. Involvement of cAMP signaling in elicitor-induced phytoalexin accumulation in Cupressus lusitanica cell cultures. THE NEW PHYTOLOGIST 2004; 161:723-733. [PMID: 33873708 DOI: 10.1111/j.1469-8137.2004.00976.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• An increasing body of evidence on plant electrophysiology, biochemistry, and molecular biology shows that cAMP exists in higher plants and plays a role in several physiological processes by affecting potassium (K+ ) or calcium (Ca2+ ) fluxes. Our study here reports that cAMP is involved in elicitor-induced accumulation of a phytoalexin, β-thujaplicin, in Cupressus lusitanica cell cultures. • Treatment of C. lusitanica cultured cells with cAMP or its analogues stimulated β-thujaplicin accumulation. Cholera toxin and forskolin, activators of adenylyl cyclase, also stimulated β-thujaplicin accumulation. Enzyme immunoassay showed that after elicitor treatment, cAMP level in the elicited cells quickly increased to about three- to five-fold over the control. Cholera toxin and forskolin also stimulated cAMP accumulation in the absence of elicitor. • However, K+ and Ca2+ channel blockers inhibited the β-thujaplicin accumulation induced by cAMP analogues, suggesting that the cAMP-stimulated β-thujaplicin accumulation may involve Ca2+ and K+ fluxes. Several ionophores mimicked cAMP induction of β-thujaplicin accumulation. • Cross-talk between cAMP treatment and the ethylene signaling pathway was also observed to work in the cell cultures via Ca2+ signaling. The study also indicates an involvement of protein kinase cascades in cAMP signaling processes, leading to both phytoalexin and ethylene production.
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Affiliation(s)
- Jian Zhao
- Laboratory of Forest Chemistry and Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581 Japan
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050 China
| | - Yingqing Guo
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050 China
| | - Koki Fujita
- Laboratory of Forest Chemistry and Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581 Japan
| | - Kokki Sakai
- Laboratory of Forest Chemistry and Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581 Japan
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30
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Mahalingam R, Fedoroff N. Stress response, cell death and signalling: the many faces of reactive oxygen species. PHYSIOLOGIA PLANTARUM 2003; 119:56-68. [PMID: 0 DOI: 10.1034/j.1399-3054.2003.00156.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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31
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Ullah H, Chen JG, Temple B, Boyes DC, Alonso JM, Davis KR, Ecker JR, Jones AM. The beta-subunit of the Arabidopsis G protein negatively regulates auxin-induced cell division and affects multiple developmental processes. THE PLANT CELL 2003; 15:393-409. [PMID: 12566580 PMCID: PMC141209 DOI: 10.1105/tpc.006148] [Citation(s) in RCA: 269] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2002] [Accepted: 10/30/2002] [Indexed: 05/18/2023]
Abstract
Plant cells respond to low concentrations of auxin by cell expansion, and at a slightly higher concentration, these cells divide. Previous work revealed that null mutants of the alpha-subunit of a putative heterotrimeric G protein (GPA1) have reduced cell division. Here, we show that this prototypical G protein complex acts mechanistically by controlling auxin sensitivity toward cell division. Loss-of-function G protein mutants have altered auxin-mediated cell division throughout development, especially during the auxin-induced formation of lateral and adventitious root primordia. Ectopic expression of the wild-type Galpha-subunit phenocopies the Gbeta mutants (auxin hypersensitivity), probably by sequestering the Gbetagamma-subunits, whereas overexpression of Gbeta reduces auxin sensitivity and a constitutively active (Q222L) mutant Galpha behaves like the wild type. These data are consistent with a model in which Gbetagamma acts as a negative regulator of auxin-induced cell division. Accordingly, basal repression of approximately one-third of the identified auxin-regulated genes (47 of 150 upregulated genes among 8300 quantitated) is lost in the Gbeta transcript-null mutant. Included among these are genes that encode proteins proposed to control cell division in root primordia formation as well as several novel genes. These results suggest that although auxin-regulated cell division is not coupled directly by a G protein, the Gbeta-subunit attenuates this auxin pathway upstream of the control of mRNA steady state levels.
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Affiliation(s)
- Hemayet Ullah
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA
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32
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Suharsono U, Fujisawa Y, Kawasaki T, Iwasaki Y, Satoh H, Shimamoto K. The heterotrimeric G protein alpha subunit acts upstream of the small GTPase Rac in disease resistance of rice. Proc Natl Acad Sci U S A 2002; 99:13307-12. [PMID: 12237405 PMCID: PMC130629 DOI: 10.1073/pnas.192244099] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2002] [Indexed: 11/18/2022] Open
Abstract
We used rice dwarf1 (d1) mutants lacking a single-copy Galpha gene and addressed Galpha's role in disease resistance. d1 mutants exhibited a highly reduced hypersensitive response to infection by an avirulent race of rice blast. Activation of PR gene expression in the leaves of the mutants infected with rice blast was delayed for 24 h relative to the wild type. H(2)O(2) production and PR gene expression induced by sphingolipid elicitors (SE) were strongly suppressed in d1 cell cultures. Expression of the constitutively active OsRac1, a small GTPase Rac of rice, in d1 mutants restored SE-dependent defense signaling and resistance to rice blast. Galpha mRNA was induced by an avirulent race of rice blast and SE application on the leaf. These results indicated the role of Galpha in R gene-mediated disease resistance of rice. We have proposed a model for the defense signaling of rice in which the heterotrimeric G protein functions upstream of the small GTPase OsRac1 in the early steps of signaling.
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Affiliation(s)
- Utut Suharsono
- Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan
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Lam BCH, Sage TL, Bianchi F, Blumwald E. Regulation of ADL6 activity by its associated molecular network. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:565-576. [PMID: 12207647 DOI: 10.1046/j.1365-313x.2002.01377.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plant dynamin-like proteins consist of a group of high molecular weight GTPase with diverse structural arrangements and cellular localizations. In addition, unlike animal dynamins, there was no evidence for the involvement of any plant dynamin-like protein in clathrin-mediated vesicle trafficking. In this study we demonstrate that ADL6 (Arabidopsis dynamin-like protein 6), due to its domain arrangement, behaves similarly to the animal dynamins. The association of ADL6 with clathrin-coated vesicles was demonstrated by co-fractionation and immunocytochemical studies. ADL6 also interacted via its C-terminus with gamma-adaptin, an adaptor protein of clathrin-coated vesicles. Our results suggest that ADL6 participates in clathrin-mediated vesicle trafficking originating from the Golgi. In addition, our studies demonstrate that ADL6 intrinsic GTPase activity is regulated by its association with acidic phospholipids and an SH3 (Src homology 3)-containing protein.
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Affiliation(s)
- Bernard C-H Lam
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
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Kim MC, Panstruga R, Elliott C, Müller J, Devoto A, Yoon HW, Park HC, Cho MJ, Schulze-Lefert P. Calmodulin interacts with MLO protein to regulate defence against mildew in barley. Nature 2002; 416:447-51. [PMID: 11919636 DOI: 10.1038/416447a] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In plants, defence against specific isolates of a pathogen can be triggered by the presence of a corresponding race-specific resistance gene, whereas resistance of a more broad-spectrum nature can result from recessive, presumably loss-of-regulatory-function, mutations. An example of the latter are mlo mutations in barley, which have been successful in agriculture for the control of powdery mildew fungus (Blumeria graminis f. sp. hordei; Bgh). MLO protein resides in the plasma membrane, has seven transmembrane domains, and is the prototype of a sequence-diversified family unique to plants, reminiscent of the seven-transmembrane receptors in fungi and animals. In animals, these are known as G-protein-coupled receptors and exist in three main families, lacking sequence similarity, that are thought to be an example of molecular convergence. MLO seems to function independently of heterotrimeric G proteins. We have identified a domain in MLO that mediates a Ca2+-dependent interaction with calmodulin in vitro. Loss of calmodulin binding halves the ability of MLO to negatively regulate defence against powdery mildew in vivo. We propose a sensor role for MLO in the modulation of defence reactions.
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Affiliation(s)
- Min C Kim
- Division of Applied Life Science (BK21 program), Plant Molecular Biology & Biotechnology Research Centre, Gyeongsang National University, Chinju 660-701, Korea
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35
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Fujisawa Y, Kato H, Iwasaki Y. Structure and function of heterotrimeric G proteins in plants. PLANT & CELL PHYSIOLOGY 2001; 42:789-94. [PMID: 11522903 DOI: 10.1093/pcp/pce111] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Heterotrimeric G proteins are mediators that transmit the external signals via receptor molecules to effector molecules. The G proteins consist of three different subunits: alpha, beta, and gamma subunits. The cDNAs or genes for all the alpha, beta, and gamma subunits have been isolated from many plant species, which has contributed to great progress in the study of the structure and function of the G proteins in plants. In addition, rice plants lacking the alpha subunit were generated by the antisense method and a rice mutant, Daikoku d1, was found to have mutation in the alpha-subunit gene. Both plants show abnormal morphology such as dwarfism, dark green leaf, and small round seed. The findings revealed that the G proteins are functional molecules regulating some body plans in plants. There is evidence that the plant G proteins participate at least in signaling of gibberellin at low concentrations. In this review, we summarize the currently known information on the structure of plant heterotrimeric G proteins and discuss the possible functions of the G proteins in plants.
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Affiliation(s)
- Y Fujisawa
- Department of Bioscience, Fukui Prefectural University, 4-1-1 Kenjyojima, Matsuoka-cho, Yoshida-gun, Fukui, 910-1195 Japan
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Bindschedler LV, Minibayeva F, Gardner SL, Gerrish C, Davies DR, Bolwell GP. Early signalling events in the apoplastic oxidative burst in suspension cultured French bean cells involve cAMP and Ca 2. THE NEW PHYTOLOGIST 2001; 151:185-194. [PMID: 33873377 DOI: 10.1046/j.1469-8137.2001.00170.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
• Modulators of cAMP, calcium and G proteins were used to treat bean (Phaseolus vulgaris) cells before addition of an elicitor from Colletotrichum lindemuthianum in order to elucidate the early steps of signal transduction leading to the production of the apoplastic oxidative burst. • Hydrogen peroxide production by elicited bean cells was monitored with luminol-or xylenol-orange-based assays. • Pretreatment with forskolin, dibutyryl cAMP or the Ca2+ ionophore A23187 enhanced the production of reactive oxygen species (ROS). The Ca2+ channel blocker, verapamil, and the calmodulin antagonist W7 led to a decreased oxidative burst and cancelled the dibutyryl cAMP effect. The production of ROS was increased by cholera toxin (CTX), an activator of G proteins. • Thus, an increase of cytosolic calcium ([Ca2+ ]cyt ) mediated through an increased level of cAMP is required for ROS production. The data support a role for G proteins and cAMP in extracellular alkalinization and Ca2+ influx, possibly in the provision of a reductant, which with the extracellular peroxidase, are required for the apoplastic oxidative burst.
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Affiliation(s)
- Laurence V Bindschedler
- Division of Biochemistry, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; Present address
| | - Farida Minibayeva
- Institute of Biochemistry and Biophysics, PO Box 30, Kazan 420503, Russia
| | - Sarah L Gardner
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Chris Gerrish
- Division of Biochemistry, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; Present address
| | - Dewi R Davies
- Division of Biochemistry, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; Present address
| | - G Paul Bolwell
- Division of Biochemistry, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; Present address
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Abstract
Heterotrimeric G-proteins, which couple cell surface receptors with internal effectors, are evident in all eukaryotes. Their operation involves receptor activation, GTP/GDP exchange and modulation of effector activity; deactivation occurs by an intrinsic GTPase activity. Structurally, G-proteins comprise three dissimilar subunits; Gα, Gβ and Gγ. The Gα subunit consists of an α-helical and a GTPase domain, the latter is responsible for interaction with Gβγ, receptor and effector. Gβ and Gγ form a tightly associated heterodimer which can also modulate effector activity when released by the activated Gα. Genome sequence and other data suggest that, in plants, there are several (~8-10?) Gα, one or two Gβ and one Gγ. These proteins are expressed throughout the plant, mainly in the plasma membrane and endoplasmic reticulum. In vivo, there is strong evidence for G-protein control of ion channels, particularly K+ , in the response pathways to fungal and bacterial pathogens as well as in some aspects of gibberellin, abscisic acid and auxin signaling pathways. Finally, future prospects for understanding plant G-protein linked signaling will rely on new and emerging technologies; these include antisense suppression, gene knockouts, yeast two-hybrid and phage display molecular approaches, intracellular immunization using recombinant single chain antibodies and expression of peptide encoding minigenes.
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Affiliation(s)
- P A Millner
- School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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38
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Wang XQ, Ullah H, Jones AM, Assmann SM. G protein regulation of ion channels and abscisic acid signaling in Arabidopsis guard cells. Science 2001; 292:2070-2. [PMID: 11408655 DOI: 10.1126/science.1059046] [Citation(s) in RCA: 412] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The phytohormone abscisic acid (ABA) promotes plant water conservation by decreasing the apertures of stomatal pores in the epidermis through which water loss occurs. We found that Arabidopsis thaliana plants harboring transferred DNA insertional mutations in the sole prototypical heterotrimeric GTP-binding (G) protein alpha subunit gene, GPA1, lack both ABA inhibition of guard cell inward K(+) channels and pH-independent ABA activation of anion channels. Stomatal opening in gpa1 plants is insensitive to inhibition by ABA, and the rate of water loss from gpa1 mutants is greater than that from wild-type plants. Manipulation of G protein status in guard cells may provide a mechanism for controlling plant water balance.
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Affiliation(s)
- X Q Wang
- Biology Department, Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802-5301, USA
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39
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Lein W, Saalbach G. Cloning and direct G-protein regulation of phospholipase D from tobacco. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1530:172-83. [PMID: 11239820 DOI: 10.1016/s1388-1981(00)00182-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phospholipase D (PLD) and heterotrimeric G-proteins are involved in plant signal transduction pathways at the plasma membrane. There is evidence suggesting that PLD acts downstream from G-proteins, but a direct interaction of specific members has not been shown. In the present paper, a PLD cDNA clone was isolated from tobacco, expressed as a GST fusion in bacteria, and the recombinant protein was purified by glutathione affinity. Its enzymatic properties identified it as an alpha-type PLD. The alpha-subunit of a G-protein from tobacco was isolated in a similar way. Both proteins were functional in biochemical assays. When the G-protein was included in the PLD assay, a strong dosage-dependent inhibition of the PLD activity was observed. Different control proteins did not exhibit this inhibitory effect. When GST-NtGPalpha1 was activated by incubation with GTPgammaS the inhibitory activity was greatly reduced. These results provide a first indication for a direct regulation of PLDalpha by a heterotrimeric G-protein alpha-subunit in plants.
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Affiliation(s)
- W Lein
- Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, D-06466, Gatersleben, Germany
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40
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Ando S, Takumi S, Ueda Y, Ueda T, Mori N, Nakamura C. Nicotiana tabacum cDNAs encoding alpha and beta subunits of a heterotrimeric GTP-binding protein isolated from hairy root tissues. Genes Genet Syst 2000; 75:211-21. [PMID: 11126570 DOI: 10.1266/ggs.75.211] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Heterotrimeric GTP-binding proteins (G-proteins) play important roles in signal transduction pathways in eukaryotic cells. Through differential screening of a hairy root cDNA library of tobacco (Nicotiana tabacum L.) against transcripts from non-root tissues of normal cuttings, we obtained a partial cDNA clone that showed abundant expression and high homology to the alpha subunit gene of plant G-protein. After RACE-PCR, a full-length cDNA clone was obtained, which was 1,677-bp in length and contained an open reading frame encoding a protein of 384 amino acids. A cDNA clone encoding a beta subunit of G-protein was also isolated from the same cDNA library based on PCR amplification and library screening. The clone was 1,600-bp in length and contained an open reading frame encoding 377 amino acids. The deduced amino acid sequences of these clones showed high homology (75.5 to 99.8% amino acid identity) with alpha and beta subunits of other plant G-proteins. Genomic Southern blot analysis showed that the amphidiploid tobacco genome possessed two major copies of both alpha and beta subunit genes and some minor homologous copies. Northern blot analysis showed that the transcript of alpha subunit gene was abundant in the root tissues, particularly in the hairy root tissues. In contrast, the level of expression of the beta subunit gene was equivalent in all the tissues studied. Possible function of tobacco G-protein was discussed.
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Affiliation(s)
- S Ando
- Laboratory of Plant Genetics, Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
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41
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Obrdlik P, Neuhaus G, Merkle T. Plant heterotrimeric G protein beta subunit is associated with membranes via protein interactions involving coiled-coil formation. FEBS Lett 2000; 476:208-12. [PMID: 10913615 DOI: 10.1016/s0014-5793(00)01706-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gbeta subunits from animals are anchored to membranes via Ggamma subunits. No Ggamma has been identified in plants to date. Using differential centrifugation of Arabidopsis and broccoli extracts, Gbeta was highly enriched in the microsomal pellet. Treatment of microsomes with detergents and salts indicates that plant Gbeta is located at the membrane surface and attached to membranes by hydrophobic interactions. Analysis of transgenic plants expressing Gbeta-GFP fusion proteins showed that mutations in the heptad repeat domain of Gbeta severely diminished their membrane association. We propose that plant Gbeta is anchored to membranes by an unknown protein similar to animal Gbeta by Ggamma, via coiled-coil formation.
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Affiliation(s)
- P Obrdlik
- Institut für Biologie II, Zellbiologie, Universität Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
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42
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Perroud PF, Diogon T, Crèvecoeur M, Greppin H. Molecular cloning, spatial and temporal characterization of spinach SOGA1 cDNA, encoding an alpha subunit of G protein. Gene 2000; 248:191-201. [PMID: 10806364 DOI: 10.1016/s0378-1119(00)00120-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterotrimeric G proteins are an important component of signal transduction pathway in animals. Although these proteins have been described in plants, their exact function and action mode are not clearly defined. In order to analyze the relationship between these proteins and the transduction of light signals in spinach, we have isolated by 5' and 3' RACE-PCR a 1660bp cDNA clone called SOGA1. This codes for a 383aa protein, which reveals a very strong homology with other plant Galpha subunit sequences. Genomic analysis suggested that SOGA1 belonged to a small multiple gene family. Northern blots and in-situ hybridization analyses showed that SOGA1 transcripts accumulate in all organs tested with a specific high level associated with the apex, roots and hypocotyls. Finally, a time-course analysis performed on the green tissues showed that accumulation of SOGA1 transcripts follows a circadian rhythm. However, in-situ hybridization analysis of the apex suggested the opposite behavior, while no variation was observed in the hypocotyl.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- Blotting, Southern
- Circadian Rhythm
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Plant/genetics
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Heterotrimeric GTP-Binding Proteins/genetics
- In Situ Hybridization
- Light
- Molecular Sequence Data
- Photoperiod
- Phylogeny
- Plants/genetics
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Plant/radiation effects
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Spinacia oleracea/genetics
- Spinacia oleracea/growth & development
- Tissue Distribution
- Transcription, Genetic/radiation effects
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Affiliation(s)
- P F Perroud
- Laboratoire de Biochimie et Physiologie Végétales, Université de Genève, place de l'Université 3, CH-1211, Geneva, Switzerland
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43
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Abstract
Calcium channels are involved principally in signal transduction. Their opening results in increased cytoplasmic Ca(2+) concentration, and the spatial and temporal variations in this are thought to elicit specific physiological responses to diverse biotic and abiotic stimuli. Calcium-permeable channels have been recorded in the plasma membrane, tonoplast, endoplasmic reticulum, chloroplast and nuclear membranes of plant cells. This article reviews their electrophysiological properties and discusses their physiological roles. Emphasis is placed on the voltage-dependent and elicitor-activated Ca(2+) channels of the plasma membrane and the depolarisation-activated (SV), hyperpolarisation-activated, IP(3)- and cADPR-dependent Ca(2+) channels of the tonoplast. The closing of stomatal guard cells in the presence of abscisic acid (ABA) is used to illustrate the co-ordination of Ca(2+) channel activities during a physiological response.
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Affiliation(s)
- P J White
- Department of Cell Physiology, Horticulture Research International, Wellesbourne, Warwick, UK.
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44
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Kaydamov C, Tewes A, Adler K, Manteuffel R. Molecular characterization of cDNAs encoding G protein alpha and beta subunits and study of their temporal and spatial expression patterns in Nicotiana plumbaginifolia Viv. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1491:143-60. [PMID: 10760577 DOI: 10.1016/s0167-4781(00)00039-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have isolated cDNA sequences encoding alpha and beta subunits of potential G proteins from a cDNA library prepared from somatic embryos of Nicotiana plumbaginifolia Viv. at early developmental stages. The predicted NPGPA1 and NPGPB1 gene products are 75-98% identical to the known respective plant alpha and beta subunits. Southern hybridizations indicate that NPGPA1 is probably a single-copy gene, whereas at least two copies of NPGPB1 exist in the N. plumbaginifolia genome. Northern analyses reveal that both NPGPA1 and NPGPB1 mRNA are expressed in all embryogenic stages and plant tissues examined and their expression is obviously regulated by the plant hormone auxin. Immunohistological localization of NPGPalpha1 and NPGPbeta1 preferentially on plasma and endoplasmic reticulum membranes and their immunochemical detection exclusively in microsomal cell fractions implicate membrane association of both proteins. The temporal and spatial expression patterns of NPGPA1 and NPGPB1 show conformity as well as differences. This could account for not only cooperative, but also individual activities of both subunits during embryogenesis and plant development.
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Affiliation(s)
- C Kaydamov
- Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, D-06466, Gatersleben, Germany
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45
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Marsh JF, Kaufman LS. Cloning and characterisation of PGA1 and PGA2: two G protein alpha-subunits from pea that promote growth in the yeast Saccharomyces cerevisiae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 19:237-47. [PMID: 10476071 DOI: 10.1046/j.1365-313x.1999.00516.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We report here on the cloning and characterization of two G protein alpha-subunits from pea: PGA1 and PGA2. Based on DNA gel blot analysis, PGA1 and PGA2 are the only Galpha homologous sequences in pea. RT-PCR analysis reveals that PGA1 and PGA2 transcripts are present in a variety of adult pea tissues. However, PGA2 mRNA is consistently detected at a lower level than PGA1 and demonstrates some degree of tissue specificity relative to PGA1. In the apical bud of pea seedlings, PGA1 and PGA2 transcripts decrease in response to 24 h of white light following growth for 6 days in darkness. The G protein mediated, yeast mating pathway was used to analyse the function of PGA1 and PGA2 in vivo. PGA1 downregulates the mating pathway, but through a mechanism that is independent of Gbetagamma sequestration. Unexpectedly, both PGA1 and PGA2 promote growth through a mating pathway independent mechanism.
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Affiliation(s)
- J F Marsh
- Department of Biological Sciences, University of Illinois at Chicago, 60607, USA
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46
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Fujisawa Y, Kato T, Ohki S, Ishikawa A, Kitano H, Sasaki T, Asahi T, Iwasaki Y. Suppression of the heterotrimeric G protein causes abnormal morphology, including dwarfism, in rice. Proc Natl Acad Sci U S A 1999; 96:7575-80. [PMID: 10377457 PMCID: PMC22128 DOI: 10.1073/pnas.96.13.7575] [Citation(s) in RCA: 186] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transgenic rice containing an antisense cDNA for the alpha subunit of rice heterotrimeric G protein produced little or no mRNA for the subunit and exhibited abnormal morphology, including dwarf traits and the setting of small seeds. In normal rice, the mRNA for the alpha subunit was abundant in the internodes and florets, the tissues closely related to abnormality in the dwarf transformants. The position of the alpha-subunit gene was mapped on rice chromosome 5 by mapping with the restriction fragment length polymorphism. The position was closely linked to the locus of a rice dwarf mutant, Daikoku dwarf (d-1), which is known to exhibit abnormal phenotypes similar to those of the transformants that suppressed the endogenous mRNA for the alpha subunit by antisense technology. Analysis of the cDNAs for the alpha subunits of five alleles of Daikoku dwarf (d-1), ID-1, DK22, DKT-1, DKT-2, and CM1361-1, showed that these dwarf mutants had mutated in the coding region of the alpha-subunit gene. These results show that the G protein functions in the formation of normal internodes and seeds in rice.
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Affiliation(s)
- Y Fujisawa
- Department of Bioscience, Fukui Prefectural University, Fukui 910-1195, Japan
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47
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Domínguez L, Yunes RM, Fornés MW, Burgos M, Mayorga LS. Calcium and phospholipase A2 are both required for the acrosome reaction mediated by G-proteins stimulation in human spermatozoa. Mol Reprod Dev 1999; 52:297-302. [PMID: 10206661 DOI: 10.1002/(sici)1098-2795(199903)52:3<297::aid-mrd7>3.0.co;2-t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
G-proteins, calcium, and phospholipase A2 (PLA2) have all been implicated in the cascade of signaling events leading to the acrosome reaction in human spermatozoa. In order to study the role of Ca+2 and PLA2 during the acrosome reaction triggered by G-proteins, we treated human spermatozoa incubated for 3 hr under capacitating conditions with several reagents (GTPgammaS, A23187, ONO-RS-082, arachidonic acid, BAPTA-AM, and TPEN), alone or in different combinations. Our results suggest that GTP-binding proteins require Ca+2 and PLA2 to accomplish their stimulatory effect, and that Ca+2 is also required when the acrosome reaction--bypassing the action of PLA2--is stimulated by AA. Accordingly, when treated with GTPgammaS or AA, the cells loaded with Fura 2-AM showed a steady increase of [Ca+2]i. On the other hand, a massive influx of Ca+2 was completely unable to induce the acrosome reaction if PLA2 was inhibited, suggesting that both an increase of [Ca+2]i and PLA2 activation are required for the acrosome reaction to occur.
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Affiliation(s)
- L Domínguez
- Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
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48
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Thuleau P, Schroeder JI, Ranjeva R. Recent advances in the regulation of plant calcium channels: evidence for regulation by G-proteins, the cytoskeleton and second messengers. CURRENT OPINION IN PLANT BIOLOGY 1998; 1:424-427. [PMID: 10066621 DOI: 10.1016/s1369-5266(98)80267-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Important aspects of the regulatory properties of plant calcium channels have been discovered during the past few years. These include the control of plasma membrane-bound channels by regulatory proteins and the characterization of a plethora of intracellular calcium release channels. Deciphering the mechanisms of regulation of different Ca2+ channels and the probable co-operation of their activities in response to various stimuli is leading to a better understanding of Ca2+-signalling processes in higher plants.
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Affiliation(s)
- P Thuleau
- Signaux et Messages Cellulaires chez les végétaux, UMR-CNRS/UPS 5546, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France.
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