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Pereira-Netto AB, Roessner U, Fujioka S, Bacic A, Asami T, Yoshida S, Clouse SD. Shooting control by brassinosteroids: metabolomic analysis and effect of brassinazole on Malus prunifolia, the Marubakaido apple rootstock. Tree Physiol 2009; 29:607-20. [PMID: 19203977 DOI: 10.1093/treephys/tpn052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
To help unravel the role of brassinosteroids (BRs) in the control of shooting, we treated the shoots of Marubakaido apple rootstock (Malus prunifolia (Willd.) Borkh cv. Marubakaido) with brassinolide and Brz 220, an inhibitor of BR biosynthesis. Brassinolide differentially affected elongation and formation of main and primary lateral shoots, which resulted in reduced apical dominance. Treatment of shoots with increasing doses of Brz 220 led to a progressive inhibition of main shoot elongation. Eight different BRs were also identified in the shoots of M. prunifolia. Progressive decline in 6-deoxocathasterone, 6-deoxotyphasterol and castasterone was related to increased doses of Brz 220. Analysis of the metabolic profiles between a fluoro-containing derivative of 28-homocastasterone (5F-HCS) using treated and untreated shoots demonstrated that no 5F-HCS-specific metabolite was identified. However, 4 weeks after the treatment, fructose, glucose and the putatively identified gulonic acid were higher in 5F-HCS-treated shoots, compared to untreated shoots. These results indicate that the previously reported 5F-HCS-induced stimulation of shoot elongation and formation of new shoots in the Marubakaido shoots is under the control of changes in the endogenous BR pool. In addition, the results presented in this report also indicate that the 5F-HCS-induced shooting likely involves a variety of different mechanisms and consequently does not result from changes in the endogenous levels of any single metabolite.
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Affiliation(s)
- Adaucto B Pereira-Netto
- Department of Botany-SCB, Paraná Federal University, Centro Politecnico, C.P. 19031, 81531-970 Curitiba-Paraná, Brazil.
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202
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Ahlfors R, Brosché M, Kollist H, Kangasjärvi J. Nitric oxide modulates ozone-induced cell death, hormone biosynthesis and gene expression in Arabidopsis thaliana. Plant J 2009; 58:1-12. [PMID: 19054359 DOI: 10.1111/j.1365-313x.2008.03756.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nitric oxide (NO) is involved together with reactive oxygen species (ROS) in the activation of various stress responses in plants. We have used ozone (O₃) as a tool to elicit ROS-activated stress responses, and to activate cell death in plant leaves. Here, we have investigated the roles and interactions of ROS and NO in the induction and regulation of O₃-induced cell death. Treatment with O₃ induced a rapid accumulation of NO, which started from guard cells, spread to adjacent epidermal cells and eventually moved to mesophyll cells. During the later time points, NO production coincided with the formation of hypersensitive response (HR)-like lesions. The NO donor sodium nitroprusside (SNP) and O₃ individually induced a large set of defence-related genes; however, in a combined treatment SNP attenuated the O₃ induction of salicylic acid (SA) biosynthesis and other defence-related genes. Consistent with this, SNP treatment also decreased O₃-induced SA accumulation. The O₃-sensitive mutant rcd1 was found to be an NO overproducer; in contrast, Atnoa1/rif1 (Arabidopsis nitric oxide associated 1/resistant to inhibition by FSM1), a mutant with decreased production of NO, was also O₃ sensitive. This, together with experiments combining O₃ and the NO donor SNP suggested that NO can modify signalling, hormone biosynthesis and gene expression in plants during O₃ exposure, and that a functional NO production is needed for a proper O₃ response. In summary, NO is an important signalling molecule in the response to O₃.
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Affiliation(s)
- Reetta Ahlfors
- Plant Biology, Department of Biological and Environmental Sciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014 Helsinki, Finland Institute of Technology, University of Tartu, Nooruse 1, Tartu 50411, Estonia
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203
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Inderjit, von Dahl CC, Baldwin IT. Use of silenced plants in allelopathy bioassays: a novel approach. Planta 2009; 229:569-75. [PMID: 19034496 DOI: 10.1007/s00425-008-0856-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 11/09/2008] [Indexed: 05/27/2023]
Abstract
Volatile phytohormones or other chemicals can affect processes in distal plant parts but may also influence neighboring plants, and thereby function allelopathically. While this hypothesis has been widely discussed, rigorous tests are lacking. Transgenic plants, silenced in the production of an emitted chemical, are ideal tools to test the hypothesis that the release of a chemical can negatively influence the growth of neighbors (allelopathy). We used isogenic wild type (WT) and genetically transformed plants that lacked the ability to produce ethylene (ir-aco), as both "emitters" and "receivers" of this volatile phytohormone in experiments where receiver plants were only exposed to the headspace of WT or ir-aco emitters, in order to evaluate if natural ethylene releases can function allelopathically. Root growth (a proxy of plant fitness) of WT receivers correlated negatively with the number of WT emitters and headspace ethylene concentrations. Reducing ethylene concentrations in the headspace with the ethylene scrubber, KMnO(4), and using ir-aco seedlings as emitters restored root growth of WT receiver seedlings. 1-Aminocyclopropane-1-carboxylic acid (ethylene biosynthesis substrate) supplementation to WT but not ir-aco emitters inhibited root growth of ir-aco, but not WT receivers, suggesting increased sensitivity to exogenous ethylene of ir-aco seedlings. We conclude that plants genetically silenced in the production of a putative allelochemical are useful in determining if the emitted chemical functions allelopathically.
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Affiliation(s)
- Inderjit
- University of Delhi, Delhi, 110007, India.
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204
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Abstract
The role of ethylene in growth and developmental responses to low phosphorus stress was evaluated using ethylene-insensitive 'Never-ripe' (Nr) tomato and etr1 petunia plants. Low phosphorus increased adventitious root formation in 'Pearson' (wild-type) tomato plants, but not in Nr, supporting a role for ethylene in adventitious root development and showing that ethylene is important for this aspect of phosphorus response. Low phosphorus reduced ethylene production by adventitious roots of both genotypes, suggesting that ethylene perception--not production--regulates carbon allocation to adventitious roots at the expense of other roots under low phosphorus stress. With the exception of its effect on adventitious rooting, Nr had positive effects on growth and biomass accumulation in tomato whereas etr1 tended to have negative effects on petunia. This was particularly evident during the recovery from transplanting, when the effective quantum yield of photosystem II of etr1 petunia grown with low phosphorus was significantly lower than 'Mitchell Diploid', suggesting that etr1 petunia plants may undergo more severe post-transplant stress at low phosphorus availability. Our results demonstrate that ethylene mediates adventitious root formation in response to phosphorus stress and plays an important role for quick recovery of plants exposed to multiple environmental stresses, i.e. transplanting and low phosphorus.
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Affiliation(s)
- Hye-Ji Kim
- Department of Horticulture, The Pennsylvania State University, University Park, PA 16802, USA
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205
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Jasinski S, Tattersall A, Piazza P, Hay A, Martinez-Garcia JF, Schmitz G, Theres K, McCormick S, Tsiantis M. PROCERA encodes a DELLA protein that mediates control of dissected leaf form in tomato. Plant J 2008; 56:603-12. [PMID: 18643984 DOI: 10.1111/j.1365-313x.2008.03628.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Leaves of seed plants can be described as simple, where the leaf blade is entire, or dissected, where the blade is divided into distinct leaflets. Mechanisms that define leaflet number and position are poorly understood and their elucidation presents an attractive opportunity to understand mechanisms controlling organ shape in plants. In tomato (Solanum lycopersicum), a plant with dissected leaves, KNOTTED1-like homeodomain proteins (KNOX) are positive regulators of leaflet formation. Conversely, the hormone gibberellin (GA) can antagonise the effects of KNOX overexpression and reduce leaflet number, suggesting that GA may be a negative regulator of leaflet formation. However, when and how GA acts on leaf development is unknown. The reduced leaflet number phenotype of the tomato mutant procera (pro) mimics that of plants to which GA has been applied during leaf development, suggesting that PRO may define a GA signalling component required to promote leaflet formation. Here we show that PRO encodes a DELLA-type growth repressor that probably mediates GA-reversible growth restraint. We demonstrate that PRO is required to promote leaflet initiation during early stages of growth of leaf primordia and conversely that reduced GA biosynthesis increases the capability of the tomato leaf to produce leaflets in response to elevated KNOX activity. We propose that, in tomato, DELLA activity regulates leaflet number by defining the correct timing for leaflet initiation.
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Affiliation(s)
- Sophie Jasinski
- Plant Sciences Department, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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206
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Imin N, Goffard N, Nizamidin M, Rolfe BG. Genome-wide transcriptional analysis of super-embryogenic Medicago truncatula explant cultures. BMC Plant Biol 2008; 8:110. [PMID: 18950541 PMCID: PMC2605756 DOI: 10.1186/1471-2229-8-110] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 10/27/2008] [Indexed: 05/08/2023]
Abstract
BACKGROUND The Medicago truncatula (M. truncatula) line 2HA has a 500-fold greater capacity to regenerate plants in culture by somatic embryogenesis than its wild type progenitor Jemalong. To understand the molecular basis for the regeneration capacity of this super-embryogenic line 2HA, using Affymetrix GeneChip(R), we have compared transcriptomes of explant leaf cultures of these two lines that were grown on media containing the auxin NAA (1-naphthaleneacetic acid) and the cytokinin BAP (6-benzylaminopurine) for two weeks, an early time point for tissue culture proliferation. RESULTS Using Affymetrix GeneChip, GCRMA normalisation and statistical analysis, we have shown that more than 196 and 49 probe sets were significantly (p < 0.05) up- or down-regulated respectively more than 2 fold in expression. We have utilised GeneBins, a database for classifying gene expression data to distinguish differentially displayed pathways among these two cultures which showed changes in number of biochemical pathways including carbon and flavonoid biosynthesis, phytohormone biosynthesis and signalling. The up-regulated genes in the embryogenic 2HA culture included nodulins, transporters, regulatory genes, embryogenesis related arabinogalactans and genes involved in redox homeostasis, the transition from vegetative growth to reproductive growth and cytokinin signalling. Down-regulated genes included protease inhibitors, wound-induced proteins, and genes involved in biosynthesis and signalling of phytohormones auxin, gibberellin and ethylene. These changes indicate essential differences between the super-embryogenic line 2HA and Jemalong not only in many aspects of biochemical pathways but also in their response to auxin and cytokinin. To validate the GeneChip results, we used quantitative real-time RT-PCR to examine the expression of the genes up-regulated in 2HA such as transposase, RNA-directed DNA polymerase, glycoside hydrolase, RESPONSE REGULATOR 10, AGAMOUS-LIKE 20, flower promoting factor 1, nodulin 3, fasciclin and lipoxygenase, and a down-regulated gene ETHYLENE INSENSITIVE 3, all of which positively correlated with the microarray data. CONCLUSION We have described the differences in transcriptomes between the M. truncatula super-embryogenic line 2HA and its non-embryogenic progenitor Jemalong at an early time point. This data will facilitate the mapping of regulatory and metabolic networks involved in the gaining totipotency and regeneration capacity in M. truncatula and provides candidate genes for functional analysis.
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Affiliation(s)
- Nijat Imin
- Australian Research Council Centre of Excellence for Integrative Legume Research, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra City, ACT 2601, Australia
| | - Nicolas Goffard
- Institut Louis Malardé, GP Box 30, 98713 Papeete Tahiti, French Polynesia
| | - Mahira Nizamidin
- Australian Research Council Centre of Excellence for Integrative Legume Research, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra City, ACT 2601, Australia
| | - Barry G Rolfe
- Australian Research Council Centre of Excellence for Integrative Legume Research, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra City, ACT 2601, Australia
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207
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Hirano K, Aya K, Hobo T, Sakakibara H, Kojima M, Shim RA, Hasegawa Y, Ueguchi-Tanaka M, Matsuoka M. Comprehensive transcriptome analysis of phytohormone biosynthesis and signaling genes in microspore/pollen and tapetum of rice. Plant Cell Physiol 2008; 49:1429-50. [PMID: 18718932 PMCID: PMC2566925 DOI: 10.1093/pcp/pcn123] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 08/18/2008] [Indexed: 05/18/2023]
Abstract
To investigate the involvement of phytohormones during rice microspore/pollen (MS/POL) development, endogenous levels of IAA, gibberellins (GAs), cytokinins (CKs) and abscisic acid (ABA) in the mature anther were analyzed. We also analyzed the global expression profiles of genes related to seven phytohormones, namely auxin, GAs, CKs, brassinosteroids, ethylene, ABA and jasmonic acids, in MS/POL and tapetum (TAP) using a 44K microarray combined with a laser microdissection technique (LM-array analysis). IAA and GA(4) accumulated in a much higher amount in the mature anther compared with the other tissues, while CKs and ABA did not. LM-array analysis revealed that sets of genes required for IAA and GA synthesis were coordinately expressed during the later stages of MS/POL development, suggesting that these genes are responsible for the massive accumulation of IAA and GA(4) in the mature anther. In contrast, genes for GA signaling were preferentially expressed during the early developmental stages of MS/POL and throughout TAP development, while their expression was down-regulated at the later stages of MS/POL development. In the case of auxin signaling genes, such mirror-imaged expression observed in GA synthesis and signaling genes was not observed. IAA receptor genes were mostly expressed during the late stages of MS/POL development, and various sets of AUX/IAA and ARF genes were expressed during the different stages of MS/POL or TAP development. Such cell type-specific expression profiles of phytohormone biosynthesis and signaling genes demonstrate the validity and importance of analyzing the expression of phytohormone-related genes in individual cell types independently of other cells/tissues.
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Affiliation(s)
- Ko Hirano
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan
| | - Koichiro Aya
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan
| | - Tokunori Hobo
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan
| | | | - Mikiko Kojima
- RIKEN Plant Science Center, Tsurumi, Yokohama, 230-0045 Japan
| | | | - Yasuko Hasegawa
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan
| | | | - Makoto Matsuoka
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan
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208
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Ehlting J, Sauveplane V, Olry A, Ginglinger JF, Provart NJ, Werck-Reichhart D. An extensive (co-)expression analysis tool for the cytochrome P450 superfamily in Arabidopsis thaliana. BMC Plant Biol 2008; 8:47. [PMID: 18433503 PMCID: PMC2383897 DOI: 10.1186/1471-2229-8-47] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2008] [Accepted: 04/23/2008] [Indexed: 05/18/2023]
Abstract
BACKGROUND Sequencing of the first plant genomes has revealed that cytochromes P450 have evolved to become the largest family of enzymes in secondary metabolism. The proportion of P450 enzymes with characterized biochemical function(s) is however very small. If P450 diversification mirrors evolution of chemical diversity, this points to an unexpectedly poor understanding of plant metabolism. We assumed that extensive analysis of gene expression might guide towards the function of P450 enzymes, and highlight overlooked aspects of plant metabolism. RESULTS We have created a comprehensive database, 'CYPedia', describing P450 gene expression in four data sets: organs and tissues, stress response, hormone response, and mutants of Arabidopsis thaliana, based on public Affymetrix ATH1 microarray expression data. P450 expression was then combined with the expression of 4,130 re-annotated genes, predicted to act in plant metabolism, for co-expression analyses. Based on the annotation of co-expressed genes from diverse pathway annotation databases, co-expressed pathways were identified. Predictions were validated for most P450s with known functions. As examples, co-expression results for P450s related to plastidial functions/photosynthesis, and to phenylpropanoid, triterpenoid and jasmonate metabolism are highlighted here. CONCLUSION The large scale hypothesis generation tools presented here provide leads to new pathways, unexpected functions, and regulatory networks for many P450s in plant metabolism. These can now be exploited by the community to validate the proposed functions experimentally using reverse genetics, biochemistry, and metabolic profiling.
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Affiliation(s)
- Jürgen Ehlting
- Institute of Plant Molecular Biology, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 28 rue Goethe, 67000 Strasbourg, France
| | - Vincent Sauveplane
- Institute of Plant Molecular Biology, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 28 rue Goethe, 67000 Strasbourg, France
| | - Alexandre Olry
- Institute of Plant Molecular Biology, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 28 rue Goethe, 67000 Strasbourg, France
| | - Jean-François Ginglinger
- Institute of Plant Molecular Biology, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 28 rue Goethe, 67000 Strasbourg, France
| | - Nicholas J Provart
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada
| | - Danièle Werck-Reichhart
- Institute of Plant Molecular Biology, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 28 rue Goethe, 67000 Strasbourg, France
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209
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Cai S, Lashbrook CC. Stamen abscission zone transcriptome profiling reveals new candidates for abscission control: enhanced retention of floral organs in transgenic plants overexpressing Arabidopsis ZINC FINGER PROTEIN2. Plant Physiol 2008; 146:1305-21. [PMID: 18192438 PMCID: PMC2259061 DOI: 10.1104/pp.107.110908] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 01/08/2008] [Indexed: 05/18/2023]
Abstract
Organ detachment requires cell separation within abscission zones (AZs). Physiological studies have established that ethylene and auxin contribute to cell separation control. Genetic analyses of abscission mutants have defined ethylene-independent detachment regulators. Functional genomic strategies leading to global understandings of abscission have awaited methods for isolating AZ cells of low abundance and very small size. Here, we couple laser capture microdissection of Arabidopsis thaliana stamen AZs and GeneChip profiling to reveal the AZ transcriptome responding to a developmental shedding cue. Analyses focus on 551 AZ genes (AZ(551)) regulated at the highest statistical significance (P < or = 0.0001) over five floral stages linking prepollination to stamen shed. AZ(551) includes mediators of ethylene and auxin signaling as well as receptor-like kinases and extracellular ligands thought to act independent of ethylene. We hypothesized that novel abscission regulators might reside in disproportionately represented Gene Ontology Consortium functional categories for cell wall modifying proteins, extracellular regulators, and nuclear-residing transcription factors. Promoter-beta-glucuronidase expression of one transcription factor candidate, ZINC FINGER PROTEIN2 (AtZFP2), was elevated in stamen, petal, and sepal AZs. Flower parts of transgenic lines overexpressing AtZFP2 exhibited asynchronous and delayed abscission. Abscission defects were accompanied by altered floral morphology limiting pollination and fertility. Hand-pollination restored transgenic fruit development but not the rapid abscission seen in wild-type plants, demonstrating that pollination does not assure normal rates of detachment. In wild-type stamen AZs, AtZFP2 is significantly up-regulated postanthesis. Phenotype data from transgene overexpression studies suggest that AtZFP2 participates in processes that directly or indirectly influence organ shed.
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Affiliation(s)
- Suqin Cai
- Department of Horticulture, Iowa State University, Ames, IA 50011-1100, USA
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210
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Vandamme P, Opelt K, Knöchel N, Berg C, Schönmann S, De Brandt E, Eberl L, Falsen E, Berg G. Burkholderia bryophila sp. nov. and Burkholderia megapolitana sp. nov., moss-associated species with antifungal and plant-growth-promoting properties. Int J Syst Evol Microbiol 2008; 57:2228-2235. [PMID: 17911288 DOI: 10.1099/ijs.0.65142-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A polyphasic taxonomic study including DNA-DNA reassociation experiments and an extensive biochemical characterization was performed on 14 Burkholderia isolates from moss gametophytes of nutrient-poor plant communities on the southern Baltic Sea coast in northern Germany. The strains were classified within two novel species, for which the names Burkholderia bryophila sp. nov. and Burkholderia megapolitana sp. nov. are proposed. The former species also includes isolates from grassland and agricultural soil collected in previous studies. Strains Burkholderia bryophila 1S18(T) (=LMG 23644(T) =CCUG 52993(T)) and Burkholderia megapolitana A3(T) (=LMG 23650(T) =CCUG 53006(T)) are the proposed type strains. They were isolated from Sphagnum rubellum and Aulacomnium palustre, respectively, growing in the 'Ribnitzer Grosses Moor' nature reserve (Mecklenburg-Pommern, Germany). All moss isolates of both novel species showed antifungal activity against phytopathogens as well as plant-growth-promoting properties.
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MESH Headings
- Antibiosis/physiology
- Antifungal Agents/metabolism
- Bryophyta/microbiology
- Burkholderia/classification
- Burkholderia/genetics
- Burkholderia/isolation & purification
- Burkholderia/metabolism
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Genes, rRNA
- Germany
- Molecular Sequence Data
- Nucleic Acid Hybridization
- Phylogeny
- Plant Growth Regulators/biosynthesis
- RNA, Bacterial/genetics
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Peter Vandamme
- Laboratorium voor Microbiologie, Universiteit Gent, K.-L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Katja Opelt
- Environmental Biotechnology, TU Graz, Petersgasse 12, A-8010 Graz, Austria
- Department of Microbiology, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| | - Nadine Knöchel
- Department of Microbiology, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| | - Christian Berg
- Institute of Plant Sciences, Karl-Franzens-Universität Graz, Holteigasse 6, A-8010 Graz, Austria
| | - Susan Schönmann
- Department of Microbiology, University of Zurich, Zollikerstraße 107, CH-8008 Zurich, Switzerland
| | - Evie De Brandt
- Laboratorium voor Microbiologie, Universiteit Gent, K.-L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Leo Eberl
- Department of Microbiology, University of Zurich, Zollikerstraße 107, CH-8008 Zurich, Switzerland
| | - Enevold Falsen
- Culture Collection, Department of Clinical Bacteriology, University of Göteborg, S-413 46 Göteborg, Sweden
| | - Gabriele Berg
- Environmental Biotechnology, TU Graz, Petersgasse 12, A-8010 Graz, Austria
- Department of Microbiology, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
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211
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Abstract
AIM To study the effect of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase from Pseudomonas fluorescens against saline stress under in vitro and field conditions in groundnut (Arachis hypogea) plants. METHODS AND RESULTS Four plant growth-promoting rhizobacteria (PGPR) strains were used in this study to evaluate their efficacy in groundnut plants against saline stress under in vitro. Among the four PGPR strains used, Ps. fluorescens strain TDK1 showed greater performance in improving the plant growth parameters of groundnut seedlings in vitro. PCR amplification using Pseudomonas-specific 16S-23S rRNA internal transcribed spacers (ITS) primers revealed that all the four strains belonged to the group of fluorescent pseudomonads. ITS region of Ps. fluorescens strain TDK1 was cloned and sequenced. ACC deaminase activity using biochemical and molecular (PCR) analysis revealed that among all the four strains, Ps. fluorescens strain TDK1 showed greater amount of ACC deaminase activity and positive reaction to PCR amplification. ACC deaminase gene from Ps. fluorescens strain TDK1 was isolated, cloned and sequenced. Pseudomonas bioformulations were developed and they were tested in groundnut plants under saline-affected soils. The results indicated the superior performance by Ps. fluorescens strain TDK1 possessing ACC deaminase activity in improving yield parameters in groundnut plants despite salinity. CONCLUSIONS Pseudomonas fluorescens strain TDK1 possessing ACC deaminase activity enhanced the saline resistance in groundnut plants, which in turn resulted in increased yield when compared with the groundnuts treated with Pseudomonas strains not having ACC deaminase activity. SIGNIFICANCE AND IMPACT OF THE STUDY The promising role of ACC deaminase from Ps. fluorescens strain TDK1 in alleviating saline stress has been concluded in groundnut plants. This study will be useful for exploiting the activity of ACC deaminase from microbial strains against various biotic and abiotic stresses wherever ACC accumulated as precursor for ethylene biosynthesis.
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Affiliation(s)
- D Saravanakumar
- Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641003, Tamil Nadu, India.
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212
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Dugardeyn J, Vandenbussche F, Van Der Straeten D. To grow or not to grow: what can we learn on ethylene-gibberellin cross-talk by in silico gene expression analysis? J Exp Bot 2008; 59:1-16. [PMID: 18212030 DOI: 10.1093/jxb/erm349] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Ethylene and gibberellins (GAs) are known to influence plant growth by mutual cross-talk and by interaction with other hormones. Transcript meta-analysis shows that GA and ethylene metabolism genes are expressed in the majority of plant organs. Both GAs and the ethylene precursor 1-amino-cyclopropane-1-carboxylic acid (ACC) may thus be synthesized ubiquitously. Transport of both hormones has been described and might hence lead to a controlled distribution. Transcript meta-analysis also suggests that applying exogenous ethylene to plants represses the expression of GA metabolism genes. Conversely, upon treatment with GAs, the expression of some ethylene synthesis genes is up-regulated. The analysis further shows that the genes coding for signalling components of these hormones are expressed throughout the entire plant. However, a tissue-specific transcript meta-analysis of ethylene synthesis and signalling genes in Arabidopsis roots suggests a more localized function of ethylene in the fast elongation and specialization zone, while GA seems to act in the (pro)meristematic zone and in the transition zone. Recent research has shown that brassinosteroids and auxins exert their function at the epidermis, consequently driving organ growth. From transcript meta-analysis data of Arabidopsis roots, it appears that GAs might also act in a cell type-specific manner.
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Affiliation(s)
- Jasper Dugardeyn
- Unit of Plant Hormone Signaling and Bio-imaging, Department of Molecular Genetics, Ghent University, Ledeganckstraat 35, B-9000 Gent, Belgium
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213
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Abstract
Plants can show remarkable responses to small changes in temperature, yet one of the great unknowns in plant science is how that temperature signal is perceived. The identity of the early components of the temperature signal transduction pathway also remains a mystery. To understand the consequences of anthropogenic environmental change we will have to learn much more about the basic biology of how plants sense temperature. Recent advances show that many known plant-temperature responses share common signalling components, and suggest ways in which these might be linked to form a plant temperature signalling network.
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Affiliation(s)
- Steven Penfield
- Centre for Novel Agricultural Products, Department of Biology, University of York, PO BOX 373, York YO190 5YW, UK
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214
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Stone SL, Callis J. Ubiquitin ligases mediate growth and development by promoting protein death. Curr Opin Plant Biol 2007; 10:624-32. [PMID: 17851112 DOI: 10.1016/j.pbi.2007.07.010] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 07/17/2007] [Accepted: 07/26/2007] [Indexed: 05/17/2023]
Abstract
The ubiquitin proteasome system (UPS) allows plants to effectively and efficiently alter their proteome so as to ensure developmental plasticity and environmental adaptation. Recent work has demonstrated that the UPS is an integral part of multiple hormone-signaling pathways, which modulate cell growth and differentiation. In response to variation in hormone levels, the UPS regulates the abundance of signaling factors, mainly hormone-responsive transcription factors, which mediate cellular responses. Recent exciting studies have shown that hormones directly or indirectly modulate substrate ubiquitination by regulating E3-substrate interaction. Other avenues of regulation include regulating E3 mRNA abundance.
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Affiliation(s)
- Sophia L Stone
- Department of Biology, Dalhousie University, 1355 Oxford St., Halifax, NS B3H 4J1, Canada
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215
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Oliver SN, Dennis ES, Dolferus R. ABA regulates apoplastic sugar transport and is a potential signal for cold-induced pollen sterility in rice. Plant Cell Physiol 2007. [PMID: 17693452 DOI: 10.1093/pep/pcm100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cold temperatures cause pollen sterility and large reductions in grain yield in temperate rice growing regions of the world. Induction of pollen sterility by cold involves a disruption of sugar transport in anthers, caused by the cold-induced repression of the apoplastic sugar transport pathway in the tapetum. Here we demonstrate that the phytohormone ABA is a potential signal for cold-induced pollen sterility (CIPS). Cold treatment of the cold-sensitive cultivar Doongara resulted in increased anther ABA levels. Exogenous ABA treatment at the young microspore stage induced pollen sterility and affected cell wall invertase and monosaccharide transporter gene expression in a way similar to cold treatment. In the cold-tolerant cultivar R31, ABA levels were significantly lower under normal circumstances and remained low after cold treatment. The differences in endogenous ABA levels in Doongara and R31 correlated with differences in expression of the ABA biosynthetic genes encoding zeaxanthin epoxidase (OSZEP1) and 9-cis-epoxycarotenoid dioxygenase (OSNCED2, OSNCED3) in anthers. The expression of three ABA-8-hydroxylase genes (ABA8OX1, 2 and 3) in R31 anthers was higher under control conditions and was regulated differently by cold compared with Doongara. Our results indicate that the cold tolerance phenotype of R31 is correlated with lower endogenous ABA levels and a different regulation of ABA metabolism.
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216
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Sakakibara H, Kyozuka J. [Cytokinin biosynthesis and novel activating pathway]. Tanpakushitsu Kakusan Koso 2007; 52:1322-9. [PMID: 17867286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
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217
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Bishop GJ. Refining the plant steroid hormone biosynthesis pathway. Trends Plant Sci 2007; 12:377-80. [PMID: 17693126 DOI: 10.1016/j.tplants.2007.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 06/20/2007] [Accepted: 07/31/2007] [Indexed: 05/12/2023]
Abstract
Many of the biochemical conversions in plant steroid hormone biosynthesis are catalysed by cytochrome P450 enzymes (CYPs or P450s). A recent paper by Toshiyuki Ohnishi et al. (2006) indicates the role of CYP90C1 and CYP90D1 in the synthesis of the most bioactive plant steroid hormone, brassinolide. These results highlight the need for refining the brassinolide biosynthesis pathway.
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Affiliation(s)
- Gerard J Bishop
- Division of Biology, Imperial College London, Wye Campus, Wye, Kent TN255AH, UK.
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218
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Oliver SN, Dennis ES, Dolferus R. ABA regulates apoplastic sugar transport and is a potential signal for cold-induced pollen sterility in rice. Plant Cell Physiol 2007; 48:1319-30. [PMID: 17693452 DOI: 10.1093/pcp/pcm100] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Cold temperatures cause pollen sterility and large reductions in grain yield in temperate rice growing regions of the world. Induction of pollen sterility by cold involves a disruption of sugar transport in anthers, caused by the cold-induced repression of the apoplastic sugar transport pathway in the tapetum. Here we demonstrate that the phytohormone ABA is a potential signal for cold-induced pollen sterility (CIPS). Cold treatment of the cold-sensitive cultivar Doongara resulted in increased anther ABA levels. Exogenous ABA treatment at the young microspore stage induced pollen sterility and affected cell wall invertase and monosaccharide transporter gene expression in a way similar to cold treatment. In the cold-tolerant cultivar R31, ABA levels were significantly lower under normal circumstances and remained low after cold treatment. The differences in endogenous ABA levels in Doongara and R31 correlated with differences in expression of the ABA biosynthetic genes encoding zeaxanthin epoxidase (OSZEP1) and 9-cis-epoxycarotenoid dioxygenase (OSNCED2, OSNCED3) in anthers. The expression of three ABA-8-hydroxylase genes (ABA8OX1, 2 and 3) in R31 anthers was higher under control conditions and was regulated differently by cold compared with Doongara. Our results indicate that the cold tolerance phenotype of R31 is correlated with lower endogenous ABA levels and a different regulation of ABA metabolism.
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219
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Castro-Sowinski S, Herschkovitz Y, Okon Y, Jurkevitch E. Effects of inoculation with plant growth-promoting rhizobacteria on resident rhizosphere microorganisms. FEMS Microbiol Lett 2007; 276:1-11. [PMID: 17711454 DOI: 10.1111/j.1574-6968.2007.00878.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) are exogenous bacteria introduced into agricultural ecosystems that act positively upon plant development. However, amendment reproducibility as well as the potential effects of inoculation upon plant root-associated microbial communities can be sources of concern. To address these questions, an understanding of mutual interactions between inoculants and resident rhizosphere microorganisms is required. Mechanisms used by PGPR can be direct or indirect; the former entails the secretion of growth regulators and the latter occurs through the production of antimicrobial compounds that reduce the deleterious effects of phytopathogens. The different modes of action may lead to different relationships between an inoculant and root microbial communities. Rhizobacterial communities are also affected by the plant, engineered genes, environmental stresses and agricultural practices. These factors appear to determine community structure more than an exogenous, active PGPR introduced at high levels.
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Affiliation(s)
- Susana Castro-Sowinski
- Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel.
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220
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Affiliation(s)
- David Weiss
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, Rehovot, Israel.
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221
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Gianinetti A, Laarhoven LJJ, Persijn ST, Harren FJM, Petruzzelli L. Ethylene production is associated with germination but not seed dormancy in red rice. Ann Bot 2007; 99:735-45. [PMID: 17347162 PMCID: PMC2802941 DOI: 10.1093/aob/mcm008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
BACKGROUND AND AIMS The relationship between ethylene production and both seed dormancy and germination was investigated using red rice (weedy rice) as a model species. METHODS Both fully dormant and after-ripened (non-dormant) naked caryopses were incubated with or without inhibitors of ethylene synthesis [aminoethoxyvinylglycine (AVG)] and perception [silver thiosulfate (STS)], or in the presence of the natural ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). The kinetics of ethylene emissions were measured with a sensitive laser-photoacoustic system. KEY RESULTS Dormant red rice caryopses did not produce ethylene. In non-dormant caryopses, ethylene evolution never preceded the first visible stage of germination (pericarp splitting), and ethylene inhibitors completely blocked ethylene production, but not pericarp splitting. Accordingly, endogenous ACC appeared to be lacking before pericarp splitting. However, early seedling growth (radicle or coleoptile attaining the length of 1 mm) followed ethylene evolution and was delayed by the inhibitors. Wounding the dormant caryopses induced them to germinate and produce ethylene, but their germination was slow and pericarp splitting could be speeded up by ethylene. CONCLUSIONS The findings suggest that, in red rice, endogenous ethylene stimulates the growth of the nascent seedling, but does not affect seed dormancy or germination inception. Correspondingly, this phytohormone does not play a role in the dormancy breakage induced by wounding, but accelerates germination after such breakage has occurred.
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Affiliation(s)
- Alberto Gianinetti
- CRA-Experimental Institute for Cereal Research, Section of Fiorenzuola, s.s. via S. Protaso 302, 29017 Fiorenzuola d'Arda (PC), Italy.
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222
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Perrig D, Boiero ML, Masciarelli OA, Penna C, Ruiz OA, Cassán FD, Luna MV. Plant-growth-promoting compounds produced by two agronomically important strains of Azospirillum brasilense, and implications for inoculant formulation. Appl Microbiol Biotechnol 2007; 75:1143-50. [PMID: 17345081 DOI: 10.1007/s00253-007-0909-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 02/23/2007] [Accepted: 02/24/2007] [Indexed: 11/29/2022]
Abstract
We evaluated phytohormone and polyamine biosynthesis, siderophore production, and phosphate solubilization in two strains (Cd and Az39) of Azospirillum brasilense used for inoculant formulation in Argentina during the last 20 years. Siderophore production and phosphate solubilization were evaluated in a chemically defined medium, with negative results. Indole 3-acetic acid (IAA), gibberellic acid (GA(3)), and abscisic acid (ABA) production were analyzed by gas chromatography-mass spectrometry. Ethylene, polyamine, and zeatin (Z) biosynthesis were determined by gas chromatography-flame ionization detector and high performance liquid chromatography (HPLC-fluorescence and -UV), respectively. Phytohormones IAA, Z, GA(3), ABA, ethylene, and growth regulators putrescine, spermine, spermidine, and cadaverine (CAD) were found in culture supernatant of both strains. IAA, Z, and GA(3) were found in all two strains; however, their levels were significantly higher (p < 0.01) in Cd (10.8, 2.32, 0.66 microg ml(-1)). ABA biosynthesis was significantly higher (p < 0.01) in Az39 (0.077 microg ml(-1)). Ethylene and polyamine CAD were found in all two strains, with highest production in Cd cultured in NFb plus L-methionine (3.94 ng ml(-1) h(-1)) and Az39 cultured in NFb plus L-lysine (36.55 ng ml(-1) h(-1)). This is the first report on the evaluation of important bioactive molecules in strains of A. brasilense as potentially capable of direct plant growth promotion or agronomic yield increase. Az39 and Cd showed differential capability to produce the five major phytohormones and CAD in chemically defined medium. This fact has important technological implications for inoculant formulation as different concentrations of growth regulators are produced by different strains or culture conditions.
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Affiliation(s)
- D Perrig
- Laboratorio de Fisiología Vegetal, Departamento de Ciencias Naturales, Universidad Nacional de Río Cuarto, Campus Universitario, CP 5800, Río Cuarto, Córdoba, Argentina
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223
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224
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Boiero L, Perrig D, Masciarelli O, Penna C, Cassán F, Luna V. Phytohormone production by three strains of Bradyrhizobium japonicum and possible physiological and technological implications. Appl Microbiol Biotechnol 2007; 74:874-80. [PMID: 17136369 DOI: 10.1007/s00253-006-0731-9] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 10/11/2006] [Accepted: 10/17/2006] [Indexed: 10/23/2022]
Abstract
The aim of this work was to evaluate phytohormone biosynthesis, siderophores production, and phosphate solubilization in three strains (E109, USDA110, and SEMIA5080) of Bradyrhizobium japonicum, most commonly used for inoculation of soybean and nonlegumes in USA, Canada, and South America. Siderophore production and phosphate solubilization were evaluated in selective culture conditions, which had negative results. Indole-3-acetic acid (IAA), gibberellic acid (GA(3)), and abscisic acid (ABA) production were analyzed by gas chromatography-mass spectrometry (GC-MS). Ethylene and zeatin biosynthesis were determined by GS-flame ionization detection and high-performance liquid chromatography (HPLC-UV), respectively. IAA, zeatin, and GA(3) were found in all three strains; however, their levels were significantly higher (p < 0.01) in SEMIA5080 (3.8 microg ml(-1)), USDA110 (2.5 microg ml(-1)), and E109 (0.87 microg ml(-1)), respectively. ABA biosynthesis was detected only in USDA110 (0.019 microg ml(-1)). Ethylene was found in all three strains, with highest production rate (18.1 ng ml(-1) h(-1)) in E109 cultured in yeast extract mannitol medium plus L-methionine. This is the first report of IAA, GA(3), zeatin, ethylene, and ABA production by B. japonicum in pure cultures, using quantitative physicochemical methodology. The three strains have differential capability to produce the five major phytohormones and this fact may have an important technological implication for inoculant formulation.
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Affiliation(s)
- L Boiero
- Laboratorio de Fisiología Vegetal, Departamento de Ciencias Naturales, Universidad Nacional de Río Cuarto, Campus Universitario, CP 5800, Río Cuarto, Córdoba, Argentina
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225
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Abstract
The size of an organism is genetically determined, yet how a plant or animal achieves its final size is largely unknown. The shoot of higher plants has a simple conserved body plan based on three major tissue systems: the epidermal (L1), sub-epidermal (L2) and inner ground and vascular (L3) tissues. Which tissue system drives or restricts growth has been a subject of debate for over a century. Here, we use dwarf, brassinosteroid biosynthesis and brassinosteroid response mutants in conjunction with tissue-specific expression of these components as tools to examine the role of the epidermis in shoot growth. We show that expression of the brassinosteroid receptor or a brassinosteroid biosynthetic enzyme in the epidermis, but not in the vasculature, of null mutants is sufficient to rescue their dwarf phenotypes. Brassinosteroid signalling from the epidermis is not sufficient to establish normal vascular organization. Moreover, shoot growth is restricted when brassinosteroids are depleted from the epidermis and brassinosteroids act locally within a leaf. We conclude that the epidermis both promotes and restricts shoot growth by providing a non-autonomous signal to the ground tissues.
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Affiliation(s)
- Sigal Savaldi-Goldstein
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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226
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Bonaventure G, Gfeller A, Proebsting WM, Hörtensteiner S, Chételat A, Martinoia E, Farmer EE. A gain-of-function allele of TPC1 activates oxylipin biogenesis after leaf wounding in Arabidopsis. Plant J 2007; 49:889-98. [PMID: 17253984 DOI: 10.1111/j.1365-313x.2006.03002.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Jasmonates, potent lipid mediators of defense gene expression in plants, are rapidly synthesized in response to wounding. These lipid mediators also stimulate their own production via a positive feedback circuit, which depends on both JA synthesis and JA signaling. To date, molecular components regulating the activation of jasmonate biogenesis and its feedback loop have been poorly characterized. We employed a genetic screen capable of detecting the misregulated activity of 13-lipoxygenase, which operates at the entry point of the jasmonate biosynthesis pathway. Leaf extracts from the Arabidopsis fou2 (fatty acid oxygenation upregulated 2) mutant displayed an increased capacity to catalyze the synthesis of lipoxygenase (LOX) metabolites. Quantitative oxylipin analysis identified less than twofold increased jasmonate levels in healthy fou2 leaves compared to wild-type; however, wounded fou2 leaves strongly increased jasmonate biogenesis compared to wounded wild-type. Furthermore, the plants displayed enhanced resistance to the fungus Botrytis cinerea. Higher than wild-type LOX activity and enhanced resistance in the fou2 mutant depend fully on a functional jasmonate response pathway. The fou2 mutant carries a missense mutation in the putative voltage sensor of the Two Pore Channel 1 gene (TPC1), which encodes a Ca(2+)-permeant non-selective cation channel. Patch-clamp analysis of fou2 vacuolar membranes showed faster time-dependent conductivity and activation of the mutated channel at lower membrane potentials than wild-type. The results indicate that cation fluxes exert strong control over the positive feedback loop whereby JA stimulates its own synthesis.
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Affiliation(s)
- Gustavo Bonaventure
- Gene Expression Laboratory, Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland
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227
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Strawn MA, Marr SK, Inoue K, Inada N, Zubieta C, Wildermuth MC. Arabidopsis Isochorismate Synthase Functional in Pathogen-induced Salicylate Biosynthesis Exhibits Properties Consistent with a Role in Diverse Stress Responses. J Biol Chem 2007; 282:5919-33. [PMID: 17190832 DOI: 10.1074/jbc.m605193200] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Salicylic acid (SA) is a phytohormone best known for its role in plant defense. It is synthesized in response to diverse pathogens and responsible for the large scale transcriptional induction of defense-related genes and the establishment of systemic acquired resistance. Surprisingly, given its importance in plant defense, an understanding of the underlying enzymology is lacking. In Arabidopsis thaliana, the pathogen-induced accumulation of SA requires isochorismate synthase (AtICS1). Here, we show that AtICS1 is a plastid-localized, stromal protein using chloroplast import assays and immunolocalization. AtICS1 acts as a monofunctional isochorismate synthase (ICS), catalyzing the conversion of chorismate to isochorismate (IC) in a reaction that operates near equilibrium (K(eq) = 0.89). It does not convert chorismate directly to SA (via an IC intermediate) as does Yersinia enterocolitica Irp9. Using an irreversible coupled spectrophotometric assay, we found that AtICS1 exhibits an apparent K(m) of 41.5 mum and k(cat) = 38.7 min(-1) for chorismate. This affinity for chorismate would allow it to successfully compete with other pathogen-induced, chorismate-utilizing enzymes. Furthermore, the biochemical properties of AtICS1 indicate its activity is not regulated by light-dependent changes in stromal pH, Mg(2+), or redox and that it is remarkably active at 4 degrees C consistent with a role for SA in cold-tolerant growth. Finally, our analyses support plastidic synthesis of stress-induced SA with the requirement for one or more additional enzymes responsible for the conversion of IC to SA, because non-enzymatic conversion of IC to SA under physiological conditions was negligible.
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Affiliation(s)
- Marcus A Strawn
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, California 94720-3102, USA
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228
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Frankowski K, Kesy J, Kopcewicz J. [Regulation of ethylene biosynthesis in plants]. Postepy Biochem 2007; 53:66-73. [PMID: 17718390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Ethylene is one of the plant hormones that controls growth and development. There are many responses regulated via ethylene in response to exogenous stimuli. Research on ethylene biosynthesis and the signalling pathway enabled us to understand the mechanism of the regulation of these responses. Different temporal and spatial expression of genes encoding enzymes involved in ethylene biosynthesis is of great importance for the regulation of ethylene responses. Also, post-translational regulation of the enzymes seems to be a key regulatory mechanism for the control of their activity. Because of versatile regulation of its production, ethylene can control plant development at many levels.
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Affiliation(s)
- Kamil Frankowski
- Zakład Fizjologii i Biologii Molekularnej Roślin, Instytut Biologii Ogólnej i Molekularnej, Uniwersytet Mikołaja Kopernika, Toruń.
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229
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Abstract
Lateral root (LR) formation is an important organogenetic process that contributes to the establishment of root architecture in higher plants. In the angiosperms, LRs are initiated from the pericycle, an inner cell layer of the parent roots. Auxin is a key plant hormone that promotes LR formation, but the molecular mechanisms of auxin-mediated LR formation remain unknown. Molecular genetic studies using Arabidopsis mutants have revealed that the auxin transport system with a balance of influx and efflux is important for LR initiation and subsequent LR primordium development. In addition, normal auxin signaling mediated by two families of transcriptional regulators, Aux/IAAs and ARFs, is necessary for LR formation. This article is an update on the mechanisms of auxin-mediated LR formation in higher plants, particularly in Arabidopsis.
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Affiliation(s)
- Hidehiro Fukaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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230
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Kloosterman B, Visser RGF, Bachem CWB. Isolation and characterization of a novel potato Auxin/Indole-3-Acetic Acid family member (StIAA2) that is involved in petiole hyponasty and shoot morphogenesis. Plant Physiol Biochem 2006; 44:766-75. [PMID: 17098436 DOI: 10.1016/j.plaphy.2006.10.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 10/10/2006] [Indexed: 05/12/2023]
Abstract
Auxin/indole-3-acetid acid (Aux/IAA) proteins are short-lived transcriptional regulators that mediate their response through interaction with auxin response factors (ARF). Although 29 Aux/IAA proteins have been identified in Arabidopsis thaliana, their individual functions are still poorly understood and are largely defined by observed growth defects in gain-of-function mutant alleles. Here we present the isolation and characterization of a novel Aux/IAA protein in potato (Solanum tuberosum) that is named StIAA2. Down regulation of StIAA2 results in distinctive phenotypes that include, increased plant height, petiole hyponasty and extreme curvature of growing leaf primordia in the shoot apex. Gene expression analysis of transgenic plants with reduced StIAA2 transcript levels resulted in the identification of a number of genes with altered expression profiles including another member of the Aux/IAA gene family (StIAA). The phenotypes that were observed in the StIAA2 suppression clones can be associated with both common as well as unique functional roles among Aux/IAA family members indicating the importance of analyzing Aux/IAA expression in different plant species.
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Affiliation(s)
- B Kloosterman
- Laboratory of Plant Breeding, Department of Plant Sciences, Graduate School of Experimental Plant Sciences, Wageningen University and Research Center, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
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231
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Abstract
AIMS The aims of the study were to identify the effects of rice endophyte Pantoea agglomerans YS19 on host plant growth and allocations of photosynthates. METHODS AND RESULTS Endophytic diazotrophic YS19 showed nitrogen-fixing activity in N-free medium, and produced four categories of phytohormones which were indole-3-acetic acid, abscisic acid, gibberellic acid and cytokinin in Luria-Bertani medium. Inoculation of YS19 improved the biomass of the 12-day-cultivated host rice seedlings by 63.4% on N-free medium or by 18.7% on N-supplemented medium. Spraying of YS19 cell culture onto the rice plants at the premilk stage enhanced the transportation of the photosynthetic assimilation product from the source (flag leaves) to the sink (stachys) significantly. The formation of the plant sink was obviously inhibited when YS19 cell culture was applied at the late milk stage. CONCLUSIONS This research suggests that endophyte YS19 promotes host rice plant growth and affects allocations of host photosynthates. SIGNIFICANCE AND IMPACT OF THE STUDY These findings suggested that YS19 possesses the potential for increasing rice production in field application. Meanwhile, a suitable plant growth stage must be selected for the foliar spraying of YS19 cell culture.
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Affiliation(s)
- Y Feng
- College of Life Sciences, Capital Normal University, Beijing, China
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232
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Nemhauser JL, Hong F, Chory J. Different plant hormones regulate similar processes through largely nonoverlapping transcriptional responses. Cell 2006; 126:467-75. [PMID: 16901781 DOI: 10.1016/j.cell.2006.05.050] [Citation(s) in RCA: 596] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 04/30/2006] [Accepted: 05/25/2006] [Indexed: 10/24/2022]
Abstract
Small-molecule hormones govern every aspect of the biology of plants. Many processes, such as growth, are regulated in similar ways by multiple hormones, and recent studies have revealed extensive crosstalk among different hormonal signaling pathways. These results have led to the proposal that a common set of signaling components may integrate inputs from multiple hormones to regulate growth. In this study, we tested this proposal by asking whether different hormones converge on a common set of transcriptional targets in Arabidopsis seedlings. Using publicly available microarray data, we analyzed the transcriptional effects of seven hormones, including abscisic acid, gibberellin, auxin, ethylene, cytokinin, brassinosteroid, and jasmonate. A high-sensitivity analysis revealed a surprisingly low number of common target genes. Instead, different hormones appear to regulate distinct members of protein families. We conclude that there is not a core transcriptional growth-regulatory module in young Arabidopsis seedlings.
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Affiliation(s)
- Jennifer L Nemhauser
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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233
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Tokunaga N, Uchimura N, Sato Y. Involvement of gibberellin in tracheary element differentiation and lignification in Zinnia elegans xylogenic culture. Protoplasma 2006; 228:179-87. [PMID: 16983485 DOI: 10.1007/s00709-006-0180-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 10/24/2005] [Indexed: 05/08/2023]
Abstract
Gibberellin (GA) is considered an important growth regulator involved in many aspects of plant development. However, little is known about the relationship between GA and lignification. In this study, we analyzed the role of GA in tracheary element (TE) differentiation and lignification using a Zinnia elegans xylogenic culture. When gibberellic acid-3 (GA3) was exogenously supplied, a slight increase in the frequency of TE differentiation and a remarkable increase in lignin content were observed. Computer image analysis of individual TEs showed that the lignification level of each TE was significantly increased in the culture treated with GA3 compared with those of the control. In contrast, suppression of TE differentiation and lignification was observed when GA biosynthesis was inhibited by ancymidol, paclobutrazol, or uniconazole. This suppression was restored by the addition of GA3. These results suggest that GA plays an important role in TE differentiation, and even more so in lignification. When conditioned medium obtained after 120 h of control culture was analyzed by high-performance liquid chromatography, many lignin precursors were detected. However, these lignin precursors were greatly reduced in the GA-treated culture. This result suggests that GA promotes lignification by activating the polymerization of lignin precursors.
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Affiliation(s)
- Naohito Tokunaga
- Department of Biology, Faculty of Science, Ehime University, Matsuyama, Japan.
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234
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Kitahata N, Han SY, Noji N, Saito T, Kobayashi M, Nakano T, Kuchitsu K, Shinozaki K, Yoshida S, Matsumoto S, Tsujimoto M, Asami T. A 9-cis-epoxycarotenoid dioxygenase inhibitor for use in the elucidation of abscisic acid action mechanisms. Bioorg Med Chem 2006; 14:5555-61. [PMID: 16682205 DOI: 10.1016/j.bmc.2006.04.025] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 04/15/2006] [Accepted: 04/17/2006] [Indexed: 11/26/2022]
Abstract
The plant hormone abscisic acid (ABA) accumulates in response to drought stress and confers stress tolerance to plants. 9-cis-Epoxycarotenoid dioxygenase (NCED), the key regulatory enzyme in the ABA biosynthesis pathway, plays an important role in ABA accumulation. Treatment of plants with abamine, the first NCED inhibitor identified, inhibits ABA accumulation. On the basis of structure-activity relationship studies of abamine, we identified an inhibitor of ABA accumulation more potent than abamine and named it abamineSG. An important structural feature of abamineSG is a three-carbon linker between the methyl ester and the nitrogen atom. Treatment of osmotically stressed plants with 100 microM abamineSG inhibited ABA accumulation by 77% as compared to the control, whereas abamine inhibited the accumulation by 35%. The expression of AB A-responsive genes and ABA catabolic genes was strongly inhibited in abamineSG-treated plants under osmotic stress. AbamineSG is a competitive inhibitor of the enzyme NCED, with a K(i) of 18.5 microM. Although the growth of Arabidopsis seedlings was inhibited by abamine at high concentrations (>50 microM), an effect that was unrelated to the inhibition of ABA biosynthesis, seedling growth was not affected by 100 microM abamineSG. These results suggest that abamineSG is a more potent and specific inhibitor of ABA biosynthesis than abamine.
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235
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Benschop JJ, Bou J, Peeters AJM, Wagemaker N, Gühl K, Ward D, Hedden P, Moritz T, Voesenek LACJ. Long-term submergence-induced elongation in Rumex palustris requires abscisic acid-dependent biosynthesis of gibberellin1. Plant Physiol 2006; 141:1644-52. [PMID: 16766669 PMCID: PMC1533959 DOI: 10.1104/pp.106.082636] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Rumex palustris (polygonceae) responds to complete submergence with enhanced elongation of its youngest petioles. This process requires the presence of gibberellin (GA) and is associated with an increase in the concentration of GA1 in elongating petioles. We have examined how GA biosynthesis was regulated in submerged plants. Therefore, cDNAs encoding GA-biosynthetic enzymes GA 20-oxidase and GA 3-oxidase, and the GA-deactivating enzyme GA 2-oxidase were cloned from R. palustris and the kinetics of transcription of the corresponding genes was determined during a 24 h submergence period. The submergence-induced elongation response could be separated into several phases: (1) during the first phase of 4 h, petiole elongation was insensitive to GA; (2) from 4 to 6 h onward growth was limited by GA; and (3) from 15 h onward underwater elongation was dependent, but not limited by GA. Submergence induced an increase of GA1 concentration, as well as enhanced transcript levels of RpGA3ox1. Exogenous abscisic acid repressed the transcript levels of RpGA20ox1 and RpGA3ox1 and thus inhibited the submergence-induced increase in GA1. Abscisic acid had no effect on the tissue responsiveness to GA.
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Affiliation(s)
- Joris J Benschop
- Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Utrecht, Sorbonnelaan 16, 3584 CA, The Netherlands
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236
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Ağar G, Türker M, Battal P, Emre EM. Phytohormone levels in germinating seeds of Zea mays L. exposed to selenium and aflatoxines. Ecotoxicology 2006; 15:443-50. [PMID: 16636889 DOI: 10.1007/s10646-006-0079-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/03/2006] [Indexed: 05/08/2023]
Abstract
Seeds of Zea mays L. were exposed to aflatoxine B1 (AFB1), aflatoxine G1 (AFG1) and selenium (Se) alone and in combination and allowed to germinate. Phytohormone levels of GA-like substances (GAs), trans-Zeatin (t-Z) and Indole-3-acetic acid (IAA) were determined by High Performance Liquid Chromatography (HPLC) when the roots of the germinating seeds reach 1.5-3.0 cm in length. The levels of endogenous hormones decreased in seeds treated with AFB1 and AFG1 compared to control; however an increase was noted in seeds exposed to AFG1 and Se together. AFB1 and Se treatment caused reduced hormone levels in most of the treatments. When plants were exposed to Se alone, the highest levels of GAs, t-Z and IAA were observed in the application of 800 ppm Se. The highest levels of GAs, t-Z and IAA were observed when seeds were treated with 0.2 ppm AFG1 + 8 ppm Se, 0.2 ppm AFG1 + 8 ppm Se and 0.2 ppm AFG1 + 0.08 ppm Se, respectively, whereas the lowest levels of the hormones were observed in 0.2 ppm AFB1 + 8 ppm Se, 0.2 ppm AFB1 + 0.08 ppm Se and 0.1 ppm AFB1, respectively. In conclusion, the levels of phytohormones were reduced by the treatment of AFB1 and AFG1 alone. However Se removed the negative effect of AFB1 on phytohormones, but not AFB1.
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Affiliation(s)
- Güleray Ağar
- Faculty of Science-Art, Department of Biology, Ataturk University, Erzurum, Turkey
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237
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Abstract
Cyanamide (NH(2)CN) has recently been isolated as a plant growth inhibitor from Vicia villosa, which is the first discovery of cyanamide from natural sources. To reveal the presence of the biosynthesized cyanamide in plants, 3.4 mM potassium ((15)N)nitrate was administered to 15- to 35-day-old plants of V. villosa, from which the cyanamide was purified and subjected to GC/MS analysis. The isotopic ratio (15)N/((14)N + (15)N) of the cyanamide was calculated to be 0.143, while that of the cyanamide extracted from V. villosa grown in the presence of a natural N source was 0.0065. The (15)N-enrichment proved de novo biosynthesis of cyanamide.
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Affiliation(s)
- Tsunashi Kamo
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Kami-ina, Nagano 399-4598, Japan.
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238
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Abstract
Gibberellins (GAs) form a large family of plant growth substances with distinct functions during the whole life cycle of higher plants. The rate of GA biosynthesis and catabolism determines how the GA hormone pool occurs in plants in a tissue and developmentally regulated manner. With the availability of genes coding for GA biosynthetic enzymes, our understanding has improved dramatically of how GA plant hormones regulate and integrate a wide range of growth and developmental processes. This review focuses on two plant systems, pumpkin and Arabidopsis, which have added significantly to our understanding of GA biosynthesis and its regulation. In addition, we present models for regulation of GA biosynthesis in transgenic plants, and discuss their suitability for altering plant growth and development.
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Affiliation(s)
- M J Pimenta Lange
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, Mendelssohnstrasse 4, 38106 Braunschweig, Germany
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239
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Tsavkelova EA, Klimova SI, Cherdyntseva TA, Netrusov AI. [Hormones and hormone-like substances of microorganisms: a review]. Prikl Biokhim Mikrobiol 2006; 42:261-8. [PMID: 16878539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Data from the literature on the ability of microorganisms to form plant hormones have been reviewed. The substances covered include abscisic acid, ethylene and other compounds with phytohormone-like properties (brassinosteroids, oligosaccharines) and analogues of animal neurotransmitters (biogenic amines). Pathways whereby the substances are metabolized and their effects on the development and activity (physiological and biochemical) of the microorganisms are considered. The role of phytohormones and hormone-like substances in the formation of association (microorganism-host) interactions are analyzed. The potential utilities of microorganisms producing hormones and hormone-like substances are discussed.
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240
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Abstract
The phytohormone abscisic acid (ABA) plays a major role as an endogenous messenger in the regulation of plant's water status. ABA is generated as a signal during a plant's life cycle to control seed germination and further developmental processes and in response to abiotic stress imposed by salt, cold, drought, and wounding. The action of ABA can target specifically guard cells for induction of stomatal closure but may also signal systemically for adjustment towards severe water shortage. At the molecular level, the responses are primarily mediated by regulation of ion channels and by changes in gene expression. In the last years, the molecular complexity of ABA signal transduction surfaced more and more. Many proteins and a plethora of "secondary" messengers that regulate or modulate ABA-responses have been identified by analysis of mutants including gene knock-out plants and by applying RNA interference technology together with protein interaction analysis. The complexity possibly reflects intensive cross-talk with other signal pathways and the role of ABA to be part of and to integrate several responses. Despite the missing unifying concept, it is becoming clear that ABA action enforces a sophisticated regulation at all levels.
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Affiliation(s)
- A Christmann
- Lehrstuhl für Botanik, Technische Universität München, Am Hochanger 4, 85354 Freising, Germany
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241
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Ayyadurai N, Ravindra Naik P, Sreehari Rao M, Sunish Kumar R, Samrat SK, Manohar M, Sakthivel N. Isolation and characterization of a novel banana rhizosphere bacterium as fungal antagonist and microbial adjuvant in micropropagation of banana. J Appl Microbiol 2006; 100:926-37. [PMID: 16629993 DOI: 10.1111/j.1365-2672.2006.02863.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM Isolation and characterization of a bacterial isolate (strain FP10) from banana rhizosphere with innate potential as fungal antagonist and microbial adjuvant in micropropagation of banana. METHODS AND RESULTS Bacterium FP10 was isolated from the banana rhizosphere and identified as Pseudomonas aeruginosa based on phenotypic, biochemical traits and sequence homology of partial 622-bp fragment of 16S ribosomal DNA (rDNA) amplicon, with the ribosomal database sequences. Strain FP10 displayed antibiosis towards fungi causing wilt and root necrosis diseases of banana. Production of plant growth hormone, indole-3-acetic acid (IAA), siderophores and phosphate-solubilizing enzyme in FP10 was determined. Strain FP10 tested negative for hydrogen cyanide, cellulase and pectinase, the deleterious traits for plant growth. Screening of antibiotic genes was carried out by polymerase chain reaction using gene-specific primers. Amplification of a 745-bp DNA fragment confirmed the presence of phlD, which is a key gene involved in the biosynthesis of 2,4-diacetylphloroglucinol (DAPG) in FP10. The antibiotic produced by FP10 was confirmed as DAPG using thin layer chromatography, high performance liquid chromatography and Fourier transform infrared and tested for fungal antibiosis towards banana pathogens. Procedures for encapsulation of banana shoot tips with FP10 are described. CONCLUSIONS Strain FP10 exhibited broad-spectrum antibiosis towards banana fungi causing wilt and root necrosis. DAPG by FP10 induced bulb formation and lysis of fungal mycelia. Encapsulation of banana shoot tips with FP10 induced higher frequency of germination (plantlet development) than nontreated controls on Murashige and Skoog basal medium. Treatment of banana plants with FP10 enhanced plant height and reduced the vascular discolouration as a result of Fusarium oxysporum f. sp. cubense FOC. SIGNIFICANCE AND IMPACT OF THE STUDY Because of the innate potential of fungal antibiosis by DAPG antibiotic and production of siderophore, plant-growth-promoting IAA and phosphatase, the strain FP10 can be used as biofertilizer as well as a biocontrol agent.
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Affiliation(s)
- N Ayyadurai
- Department of Biotechnology, Pondicherry University, Kalapet, Pondicherry, India
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242
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Martin-Trillo M, Lázaro A, Poethig RS, Gómez-Mena C, Piñeiro MA, Martinez-Zapater JM, Jarillo JA. EARLY IN SHORT DAYS 1(ESD1) encodes ACTIN-RELATED PROTEIN 6 (AtARP6), a putative component of chromatin remodelling complexes that positively regulatesFLCaccumulation inArabidopsis. Development 2006; 133:1241-52. [PMID: 16495307 DOI: 10.1242/dev.02301] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have characterized Arabidopsis esd1 mutations, which cause early flowering independently of photoperiod, moderate increase of hypocotyl length, shortened inflorescence internodes, and altered leaf and flower development. Phenotypic analyses of double mutants with mutations at different loci of the flowering inductive pathways suggest that esd1 abolishes the FLC-mediated late flowering phenotype of plants carrying active alleles of FRI and of mutants of the autonomous pathway. We found that ESD1 is required for the expression of the FLCrepressor to levels that inhibit flowering. However, the effect of esd1 in a flc-3 null genetic background and the downregulation of other members of the FLC-like/MAF gene family in esd1 mutants suggest that flowering inhibition mediated by ESD1 occurs through both FLC-and FLC-like gene-dependent pathways. The ESD1 locus was identified through a map-based cloning approach. ESD1 encodes ARP6, a homolog of the actin-related protein family that shares moderate sequence homology with conventional actins. Using chromatin immunoprecipitation (ChIP) experiments,we have determined that ARP6 is required for both histone acetylation and methylation of the FLC chromatin in Arabidopsis.
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Affiliation(s)
- Mar Martin-Trillo
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, C/ Darwin 3, Madrid 28049, Spain
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243
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Tsavkelova EA, Klimova SI, Cherdyntseva TA, Netrusov AI. [Microbial producers of plant growth stimulators and their practical use: A review]. Prikl Biokhim Mikrobiol 2006; 42:133-43. [PMID: 16761564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The ability of pro- and eukaryotic microorganisms to synthesize growth-stimulating phytohormones is reviewed, with emphasis on pathways of biosynthesis of these compounds and their effects on physiological and biochemical properties of the producers. Phytohormones are viewed as specific mediators in interactions between various organisms inhabiting the same ecological niche, the biological role of which is not limited to processes taking place in plants. In addition to setting forth theoretical aspects of this problem, the review underscores the need to utilize such producer microorganisms in plant cultivation and biotechnology.
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Kim HB, Kwon M, Ryu H, Fujioka S, Takatsuto S, Yoshida S, An CS, Lee I, Hwang I, Choe S. The regulation of DWARF4 expression is likely a critical mechanism in maintaining the homeostasis of bioactive brassinosteroids in Arabidopsis. Plant Physiol 2006; 140:548-57. [PMID: 16407451 PMCID: PMC1361323 DOI: 10.1104/pp.105.067918] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Mutants that are defective in brassinosteroid (BR) biosynthesis or signaling display severely retarded growth patterns due to absence of growth-promoting effects by BRs. Arabidopsis (Arabidopsis thaliana) DWARF4 (DWF4) catalyzes a flux-determining step in the BR biosynthetic pathways. Thus, it is hypothesized that the tissues of DWF4 expression may represent the sites of BR biosynthesis in Arabidopsis. Here we show that DWF4 transcripts accumulate in the actively growing tissues, such as root, shoot apices with floral clusters, joint tissues of root and shoot, and dark-grown seedlings. Conforming to the RNA gel-blot analysis, DWF4:beta-glucuronidase (GUS) histochemical analyses more precisely define the tissues that express the DWF4 gene. Examination of the endogenous levels of BRs in six and seven different tissues of wild type and brassinosteroid insensitive1-5 mutant, respectively, revealed that BRs are significantly enriched in roots, shoot tips, and joint tissues of roots and shoots. In addition, DWF4:GUS expression was negatively regulated by BRs. DWF4:GUS activity was increased by treatment with brassinazole, a BR biosynthetic inhibitor, and decreased by exogenous application of bioactive BRs. When DWF4:GUS was expressed in a different genetic background, its level was down-regulated in brassinazole resistant1-D, confirming that BRASSINAZOLE RESISTANT1 acts as a negative regulator of DWF4. Interestingly, in the brassinosteroid insensitive2/dwf12-1D background, DWF4:GUS expression was intensified and delocalized to elongating zones of root, suggesting that BRASSINOSTEROID INSENSITIVE2 is an important factor that limits DWF4 expression. Thus, it is likely that the DWF4 promoter serves as a focal point in maintaining homeostasis of endogenous bioactive BR pools in specific tissues of Arabidopsis.
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Affiliation(s)
- Ho Bang Kim
- Department of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea
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245
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Abstract
Mutants that branch profusely in the presence of a growing shoot tip have highlighted the role of graft-transmissible signals that are produced in roots and stem. Orthologous genes in Arabidopsis, pea and petunia are involved in the transmission of a novel long-distance message. These genes show varying degrees of regulation by auxin and an auxin-independent feedback system, and encode enzymes that might act on carotenoid-like substrates. Axillary bud outgrowth is under homeostatic control, involving developmental stages or checkpoints. Perturbation of the long-range messaging and auxin depletion does not guarantee that bud outgrowth will ensue at a particular node.
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Affiliation(s)
- Christine A Beveridge
- ARC Centre of Excellence in Integrative Legume Research, The University of Queensland, Brisbane 4072, Australia.
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246
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Abstract
AIMS To examine the production of gibberellic acid by selected morphological mutants of Gibberella fujikuroi in liquid cultures. METHODS AND RESULTS Mutants of G. fujikuroi having different morphological characteristics were selected after UV irradiation. The production of gibberellic acid by mutants that had different hyphal lengths was examined in shake flasks in media with different concentrations of nutrients as well as different volumes of the medium. Fed-batch fermenter study was performed to evaluate the mutant Mor-25 for growth and production of gibberellic acid. The broth was analysed by high performance liquid chromatography for fusaric acid, the common mycotoxin produced by strains of Fusarium. A variety of morphological mutants having different mycelial and soluble pigmentation as well as colony morphologies were generated from G. fujikuroi upon exposure to UV radiation. A nonpigmented mutant (Car-1) was selected as intermediate parent and later, mutants Mor-1 and Mor-25 were selected based on their distinct morphology. The colonies on regeneration agar plates were small, compact and dry. In liquid medium, mutant Mor-25 grew in a micro-pelleted form and the mycelium had short, highly branched hyphae, curly at tips with thick, swollen cells. Mutant Mor-25 grew rapidly in a low-cost medium containing defatted groundnut flour, sucrose and salts. In media with higher nutrient concentrations as well as larger volumes, it produced twofold more gibberellic acid than the parent. Fusaric acid, the common mycotoxin, was absent in the fermentation broth of mutant Mor-25. The mutants have been deposited in National Collection of Industrial Microorganisms (NCIM), National Chemical Laboratory, Pune, India under following culture collection numbers (Car-1, NCIM 1323; Mor-1, NCIM 1322; and Mor-25, NCIM 1321). CONCLUSIONS Growth of unpigmented, morphological mutants of G. fujikuroi that led to lower viscosity in fermentation broth resulted in increased production of gibberellic acid. SIGNIFICANCE AND IMPACT OF THE STUDY The use of morphological mutants that have lower viscosity in liquid cultures for gibberellic acid production is not reported earlier. Similar mutants can be useful for other types of fungal fermentations also.
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Affiliation(s)
- G Lale
- Chemical Engineering Division, National Chemical Laboratory, Pune, India
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247
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Joo GJ, Kim YM, Kim JT, Rhee IK, Kim JH, Lee IJ. Gibberellins-producing rhizobacteria increase endogenous gibberellins content and promote growth of red peppers. J Microbiol 2005; 43:510-5. [PMID: 16410767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The growth of red pepper plants was enhanced by treatment with the rhizobacterium, Bacillus cereus MJ-1. Red pepper shoots showed a 1.38-fold increase in fresh weight (fw) and roots showed a 1.28-fold fw gain. This plant growth-promoting rhizobacterium (PGPR) has been reported to produce gibberellins (GAs). Other GAs-producing rhizobacteria, Bacillus macroides CJ-29 and Bacillus pumilus CJ-69, also enhanced the fw of the plants. They were less effective than B. cereus MJ-1, though. The endogenous GAs content of pepper shoots inoculated with MJ-1 was also higher than in shoots inoculated with CJ-29 or CJ-69. When inoculated with MJ-1, bacterial colonization rate of the roots was higher than that of roots inoculated with CJ-29 or CJ-69. These results support the idea that the plant growth-promoting effect of the bacteria also positively related with the efficiency of root colonization by the bacteria. In addition, we identified the major endogenous GAs of the red pepper as originating from both the early C-13 hydroxylation and the early non C-13 hydroxylation pathways, with the latter being the predominant pathway of GA biosynthesis in red pepper shoots.
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Affiliation(s)
- Gil-Jae Joo
- Institute of Agricultural Science and Technology, Kyungpook National University, Daegu, Republic of Korea
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248
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Abstract
The early steps in the gibberellin (GA) biosynthetic pathway are controlled by single copy genes or small gene families. In pea (Pisum sativum L.) there are two ent-kaurenoic acid oxidases, one expressed only in the seeds, while ent-copalyl synthesis and ent-kaurene oxidation appear to be controlled by single copy genes. None of these genes appear to show feedback regulation and the only major developmental regulation appears to be during seed development. During shoot maturation, transcript levels do not change markedly with the result that all the three genes examined are expressed in mature tissue, supporting recent findings that these tissues can synthesise GAs. It therefore appears that the regulation of bioactive GA levels are determined by the enzymes encoded by the 2-oxoglutarate-dependent dioxygenase gene families controlling the later steps in GA biosynthesis. However the early steps are nonetheless important as a clear log/linear relationship exists between elongation and the level of GA1 in a range of single and double mutants in genes controlling these steps.
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Affiliation(s)
- Sandra E Davidson
- School of Plant Science, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
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249
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Abstract
Brassinosteroids are plant-specific steroid hormones that have an important role in coupling environmental factors, especially light, with plant growth and development. How the endogenous brassinosteroids change in response to environmental stimuli is largely unknown. Ca2+/calmodulin has an essential role in sensing and transducing environmental stimuli. Arabidopsis DWARF1 (DWF1) is responsible for an early step in brassinosteroid biosynthesis that converts 24-methylenecholesterol to campesterol. Here we show that DWF1 is a Ca2+/calmodulin-binding protein and this binding is critical for its function. Molecular genetic analysis using site-directed and deletion mutants revealed that loss of calmodulin binding completely abolished the function of DWF1 in planta, whereas partial loss of calmodulin binding resulted in a partial dwarf phenotype in complementation studies. These results provide direct proof that Ca2+/calmodulin-mediated signalling has a critical role in controlling the function of DWF1. Furthermore, we observed that DWF1 orthologues from other plants have a similar Ca2+/calmodulin-binding domain, implying that Ca2+/calmodulin regulation of DWF1 and its homologues is common in plants. These results raise the possibility of producing size-engineered crops by altering the Ca2+/calmodulin-binding property of their DWF1 orthologues.
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Affiliation(s)
- Liqun Du
- Center for Integrated Biotechnology and Department of Horticulture, Washington State University, Pullman, Washington 99164-6414, USA
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250
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Pandey P, Kang SC, Gupta CP, Maheshwari DK. Rhizosphere competent Pseudomonas aeruginosa GRC1 produces characteristic siderophore and enhances growth of Indian mustard (Brassica campestris). Curr Microbiol 2005; 51:303-9. [PMID: 16211433 DOI: 10.1007/s00284-005-0014-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Pseudomonas aeruginosa GRC1, an isolate of potato rhizosphere, was known to have several plant growth-promoting activities, including production of phytohormone and antibiotic substance. The isolate was found to have prolific production ability of hydroxamate siderophore in iron-deficient conditions. The siderophore of GRC1 was purified and characterized. The purified siderophore appeared to be of pyoverdin type with typical amino acid composition. In field trials, P. aeruginosa GRC1 enhanced the growth of Brassica campestris var Pusa Gold (Indian mustard). Significant increase in root and shoot weight, length, grain yield per plant, and total grain yield was recorded. Root colonization was studied with Tn5-induced streptomycin-resistant transconjugants of spontaneous rifampicin-resistant GRC1 (designated GRC1(rif+strep+)) after different durations. The strain was significantly rhizopheric competent and stabilized in the rhizosphere, without disturbing the normal indigenous bacterial population.
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Affiliation(s)
- Piyush Pandey
- S.B.S.P.G.I. Balawala, Dehradun, (U. A. India), 248161
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