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Methods for Detecting Biocontrol and Plant Growth-Promoting Traits in Rhizobacteria. METHODS IN RHIZOSPHERE BIOLOGY RESEARCH 2019. [DOI: 10.1007/978-981-13-5767-1_8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Karthik C, Elangovan N, Kumar TS, Govindharaju S, Barathi S, Oves M, Arulselvi PI. Characterization of multifarious plant growth promoting traits of rhizobacterial strain AR6 under Chromium (VI) stress. Microbiol Res 2017; 204:65-71. [PMID: 28870293 DOI: 10.1016/j.micres.2017.07.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/12/2017] [Accepted: 07/20/2017] [Indexed: 10/19/2022]
Abstract
Plant growth promoting rhizobacteria (PGPR) can increase the host plant tolerance to cope up with heavy metal induced stress, which can be improve plant growth. Thus, the present study was designed to isolate Cr(VI) tolerant PGPR strain and evaluate its plant growth promoting (PGP) properties under Cr(VI) stress. Rhizobacterial strain AR6 was isolated from the rhizosphere of Phaseolus vulgaris L. and showed 99% homology with Cellulosimicrobium funkei (KM032184) in BLASTn analysis. Strain AR6 was specifically selected due to its high Cr(VI) tolerance (1200μg/ml) and substantial production of PGP substances. Strain AR6 produced 36.75μg/ml of indole acetic acid (IAA), 60.40μg/ml of ammonia and 14.23μg/ml of exopolysaccharide (EPS). Moreover, strain AR6 showed positive results for catalase, protease, amylase, lipase production and phosphate solubilization. A trend of Cr(VI) concentration dependent progressive decline for PGP traits of strain AR6 was observed excluding EPS which was regularly increased on increasing concentrations of Cr(VI). Among the four tested Cr(VI) concentrations, 250μg/ml showed the maximum toxicity to PGP activities of strain AR6. Inoculation of rhizobacterial strain AR6 significantly increased the root length of test crops in the presence of Cr(VI) and produced a considerable number of colonizes on the root of versatile dicot and monocot plants. Moreover, strain AR6 exhibited strong antagonistic activity against phytopathogen Aspergillus niger. Thus, the present study suggests that metal tolerant and PGP activities of the rhizobacterial strain AR6 could be exploited for environmental and agricultural issues.
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Affiliation(s)
- Chinnannan Karthik
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India; DRDO - BU - Centre for Life Sciences, Coimbatore, Tamil Nadu, India
| | - Namasivayam Elangovan
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India
| | - Thamilarasan Senthil Kumar
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India
| | - Subramani Govindharaju
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India
| | - Selvaraj Barathi
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India
| | - Mohammad Oves
- Center of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Padikasan Indra Arulselvi
- Plant and Microbial Biotechnology Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem, 636 011, Tamil Nadu, India.
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Colonization of plant roots and enhanced atrazine degradation by a strain of Arthrobacter ureafaciens. Appl Microbiol Biotechnol 2017; 101:6809-6820. [PMID: 28699022 PMCID: PMC5554279 DOI: 10.1007/s00253-017-8405-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/10/2017] [Accepted: 06/20/2017] [Indexed: 11/24/2022]
Abstract
Our previous research found that culturable atrazine degraders associated with maize roots were dominated by genetically similar strains of Arthrobacter ureafaciens, suggesting their rhizosphere competence. The present study aimed to assess the root-colonizing capacity of strain A. ureafaciens DnL1-1 and to evaluate consequent root-associated degradation of atrazine. A soil-sand assay and pot experiments provided evidence that A. ureafaciens DnL1-1 competitively colonized roots of maize, wheat, and alfalfa following seed inoculation. Atrazine was not absolutely required but promoted colonization of plant roots by the bacterium. In association with plants, A. ureafaciens DnL1-1 enhanced the degradation of atrazine and strongly reduced accumulation of its dealkylated metabolites. Our results show that after low-level inoculation of seeds, the bacterium A. ureafaciens DnL1-1 can establish root populations sufficient for the rapid degradation of atrazine in soil that makes it a promising bioremediation agent which can be easily applied to large areas of polluted soil. Application of the root-colonizing, atrazine-degrading Arthrobacter bacteria as seed inoculants may be a reliable remediation strategy for soils contaminated with chlorinated s-triazines and their degradation products.
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Płociniczak T, Fic E, Pacwa-Płociniczak M, Pawlik M, Piotrowska-Seget Z. Improvement of phytoremediation of an aged petroleum hydrocarbon-contaminated soil by Rhodococcus erythropolis CD 106 strain. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2017; 19:614-620. [PMID: 28103078 DOI: 10.1080/15226514.2016.1278420] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The aim of this study was to assess the impact of soil inoculation with the Rhodococcus erythropolis CD 106 strain on the effectiveness of the phytoremediation of an aged hydrocarbon-contaminated [approx. 1% total petroleum hydrocarbon (TPH)] soil using ryegrass (Lolium perenne). The introduction of CD 106 into the soil significantly increased the biomass of ryegrass and the removal of hydrocarbons in planted soil. The fresh weight of the shoots and roots of plants inoculated with CD 106 increased by 49% and 30%, respectively. After 210 days of the experiment, the concentration of TPH was reduced by 31.2%, whereas in the planted, non-inoculated soil, it was reduced by 16.8%. By contrast, the concentration of petroleum hydrocarbon decreased by 18.7% in non-planted soil bioaugmented with the CD 106 strain. The rifampicin-resistant CD 106 strain survived after inoculation into soil and was detected in the soil during the entire experimental period, but the number of CD 106 cells decreased constantly during the enhanced phytoremediation and bioaugmentation experiments. The plant growth-promoting and hydrocarbon-degrading properties of CD 106, which are connected with its long-term survival and limited impact on autochthonous microflora, make this strain a good candidate for improving the phytoremediation efficiency of soil contaminated with hydrocarbons.
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Affiliation(s)
- Tomasz Płociniczak
- a Department of Microbiology , University of Silesia , Katowice , Poland
| | - Ewa Fic
- a Department of Microbiology , University of Silesia , Katowice , Poland
| | | | - Małgorzata Pawlik
- a Department of Microbiology , University of Silesia , Katowice , Poland
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Fluorescent Pseudomonas sp. PF17 as an efficient plant growth regulator and biocontrol agent for sunflower crop under saline conditions. Symbiosis 2016. [DOI: 10.1007/s13199-016-0389-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kolton M, Frenkel O, Elad Y, Cytryn E. Potential role of Flavobacterial gliding-motility and type IX secretion system complex in root colonization and plant defense. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1005-1013. [PMID: 24921925 DOI: 10.1094/mpmi-03-14-0067-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility complex that is tightly associated with a recently characterized Bacteroidetes-specific type IX protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approximately 10-fold), plant root colonization (approximately fivefold), and seed adhesion capacity (approximately sevenfold) than the wild-type strains. Furthermore, the biocontrol capacity of the mutant strain toward foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild-type strain, suggesting a role of the gliding and secretion complex in plant protection. Collectively, these results provide an initial link between the high abundance of flavobacteria in the rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility and secretion complex may play a central role in root colonization and plant defense.
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Piotrowska-Seget Z, Beściak G, Bernaś T, Kozdrój J. GFP-tagged multimetal-tolerant bacteria and their detection in the rhizosphere of white mustard. ANN MICROBIOL 2012; 62:559-567. [PMID: 22661921 PMCID: PMC3351603 DOI: 10.1007/s13213-011-0292-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 06/01/2011] [Indexed: 11/20/2022] Open
Abstract
The introduction of rhizobacteria that tolerate heavy metals is a promising approach to support plants involved in phytoextraction and phytostabilisation. In this study, soil of a metal-mine wasteland was analyzed for the presence of metal-tolerant bacterial isolates, and the tolerance patterns of the isolated strains for a number of heavy metals and antibiotics were compared. Several of the multimetal-tolerant strains were tagged with a broad host range reporter plasmid (i.e. pPROBE-NT) bearing a green fluorescent protein marker gene (gfp). Overall, the metal-tolerant isolates were predominately Gram-negative bacteria. Most of the strains showed a tolerance to five metals (Zn, Cu, Ni, Pb and Cd), but with differing tolerance patterns. From among the successfully tagged isolates, we used the transconjugant Pseudomonas putida G25 (pPROBE-NT) to inoculate white mustard seedlings. Despite a significant decrease in transconjugant abundance in the rhizosphere, the gfp-tagged cells survived on the root surfaces at a level previously reported for root colonisers.
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Plant exudates promote PCB degradation by a rhodococcal rhizobacteria. Appl Microbiol Biotechnol 2011; 95:1589-603. [PMID: 22202970 DOI: 10.1007/s00253-011-3824-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/04/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
Rhodococcus erythropolis U23A is a polychlorinated biphenyl (PCB)-degrading bacterium isolated from the rhizosphere of plants grown on a PCB-contaminated soil. Strain U23A bphA exhibited 99% identity with bphA1 of Rhodococcus globerulus P6. We grew Arabidopsis thaliana in a hydroponic axenic system, collected, and concentrated the plant secondary metabolite-containing root exudates. Strain U23A exhibited a chemotactic response toward these root exudates. In a root colonizing assay, the number of cells of strain U23A associated to the plant roots (5.7 × 10⁵ CFU g⁻¹) was greater than the number remaining in the surrounding sand (4.5 × 10⁴ CFU g⁻¹). Furthermore, the exudates could support the growth of strain U23A. In a resting cell suspension assay, cells grown in a minimal medium containing Arabidopsis root exudates as sole growth substrate were able to metabolize 2,3,4'- and 2,3',4-trichlorobiphenyl. However, no significant degradation of any of congeners was observed for control cells grown on Luria-Bertani medium. Although strain U23A was unable to grow on any of the flavonoids identified in root exudates, biphenyl-induced cells metabolized flavanone, one of the major root exudate components. In addition, when used as co-substrate with sodium acetate, flavanone was as efficient as biphenyl to induce the biphenyl catabolic pathway of strain U23A. Together, these data provide supporting evidence that some rhodococci can live in soil in close association with plant roots and that root exudates can support their growth and trigger their PCB-degrading ability. This suggests that, like the flagellated Gram-negative bacteria, non-flagellated rhodococci may also play a key role in the degradation of persistent pollutants.
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Müller H, Westendorf C, Leitner E, Chernin L, Riedel K, Schmidt S, Eberl L, Berg G. Quorum-sensing effects in the antagonistic rhizosphere bacterium Serratia plymuthica HRO-C48. FEMS Microbiol Ecol 2009; 67:468-78. [PMID: 19220861 DOI: 10.1111/j.1574-6941.2008.00635.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The rhizosphere-associated bacterium Serratia plymuthica HRO-C48 is not only able to suppress symptoms caused by soil-borne pathogens but is also able to stimulate growth of plants. Detailed knowledge about the underlying mechanisms and regulation are crucial for the application in biocontrol strategies. To analyse the influence of N-acyl homoserine lactone (AHL)-mediated communication on the biocontrol activity, the AHL-degrading lactonase AiiA was heterologously expressed in the strain, resulting in abolished AHL production. The comparative analysis of the wild type and AHL negative mutants led to the identification of new AHL-regulated phenotypes. In the pathosystem Verticillium dahliae-oilseed rape, the essential role of AHL-mediated signaling for disease suppression was demonstrated. In vitro, the regulatory function of AHLs in the synthesis of the plant growth hormone indole-3-acetic acid is shown for the first time. Additionally, swimming motility was found to be negatively AHL regulated. In contrast, production of extracellular hydrolytic enzymes is shown to be positively AHL-regulated. HRO-C48 emits a broad spectrum of volatile organic compounds that are involved in antifungal activity and, interestingly, whose relative abundances are influenced by quorum sensing (QS). This study shows that QS is crucial for biocontrol activity of S. plymuthica and discusses the impact for the application of the strain as a biocontrol agent.
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Affiliation(s)
- Henry Müller
- Department of Environmental Biotechnology, Graz University of Technology, Graz, Austria
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Kurze S, Bahl H, Dahl R, Berg G. Biological Control of Fungal Strawberry Diseases by Serratia plymuthica HRO-C48. PLANT DISEASE 2001; 85:529-534. [PMID: 30823130 DOI: 10.1094/pdis.2001.85.5.529] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
To develop a biological control product for commercial strawberry production, the chitinolytic rhizobacterium Serratia plymuthica strain HRO-C48 was evaluated for plant growth promotion of strawberries and biological control of the fungal pathogens Verticillium dahliae and Phytophthora cactorum. In phytochamber experiments, treatment with S. plymuthica HRO-C48 resulted in a statistically significant enhancement of plant growth dependent on the concentration of the bacterium that was applied. In greenhouse trials, bacterial treatment reduced the percentage of Verticillium wilt (18.5%) and Phytophthora root rot (33.4%). In three consecutive vegetation periods, field trials were carried out in soil naturally infested by both soilborne pathogens on commercial strawberry farms located in various regions of Germany. Dipping plants in a suspension of S. plymuthica prior to planting reduced Verticillium wilt compared with the nontreated control by 0 to 37.7%, with an average of 24.2%, whereas the increase of yield ranged from 156 to 394%, with an average of 296%. Bacterial treatment reduced Phy-tophthora root rot by 1.3 to 17.9%, with an average of 9.6%, and increased strawberry yield by 60% compared with the nontreated control. Under field conditions, strain HRO-C48 survived at approximately log10 3 to 7 CFU/g of root in the strawberry rhizosphere at 14 months after root application. Although results of the field trials were influenced by pathogen inoculum density, cropping history of the field site, and weather conditions, S. plymuthica HRO-C48 successfully controlled wilt and root rot of strawberry.
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Affiliation(s)
- Stefan Kurze
- University of Rostock, Institute of Molecular Physiology and Biotechnology, Microbiology, D-18051 Rostock, Germany
| | - Hubert Bahl
- University of Rostock, Institute of Molecular Physiology and Biotechnology, Microbiology, D-18051 Rostock, Germany
| | - Robert Dahl
- Strawberry Farm Rövershagen, Dorfstraße 2, D-18182 Purkshof, Germany
| | - Gabriele Berg
- University of Rostock, Institute of Molecular Physiology and Biotechnology, Microbiology
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Lottmann J, Heuer H, De Vries J, Mahn A, Düring K, Wackernagel W, Smalla K, Berg G. Establishment of introduced antagonistic bacteria in the rhizosphere of transgenic potatoes and their effect on the bacterial community. FEMS Microbiol Ecol 2000; 33:41-49. [PMID: 10922502 DOI: 10.1111/j.1574-6941.2000.tb00725.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In a field release experiment, rifampicin resistant mutants of two antagonistic plant-associated bacteria were used for seed tuber inoculation of transgenic T4 lysozyme expressing potatoes, transgenic control potatoes and non-transgenic parental potatoes. The T4 lysozyme tolerant Pseudomonas putida QC14-3-8 was originally isolated from the tuber surface (geocaulosphere) of T4 lysozyme producing plants and showed in vitro antibacterial activity to the bacterial pathogen Erwinia carotovora ssp. atroseptica. The T4 lysozyme sensitive Serratia grimesii L16-3-3 was originally isolated from the rhizosphere of parental potatoes and showed in vitro antagonism toward the plant pathogenic fungus Verticillium dahliae. The establishment of the inoculated bacteria in the rhizosphere and geocaulosphere of the different plant lines was monitored over one growing season to assess the effect of T4 lysozyme produced by transgenic potato plants on the survival of both inoculants. Both introduced isolates were able to colonize the rhizo- and geocaulosphere of transgenic plants and non-transgenic parental plants, and established in the rhizosphere at levels of ca. log(10) 5 colony forming units g(-1) fresh weight of root. During flowering of plants, significantly more colony counts of the T4 lysozyme tolerant P. putida were recovered from transgenic T4 lysozyme plants than from the transgenic control and the parental line. At this time, the highest level of T4 lysozyme (% of total soluble protein) was detected. Effects of the inoculants on the indigenous microbial community were monitored by analysis of PCR-amplified fragments of the 16S rRNA genes of the whole bacterial community after separation by denaturing gradient gel electrophoresis (DGGE). At any sampling time, the DGGE pattern of rhizosphere and geocaulosphere communities did not show differences between the inoculated and non-inoculated potatoes. Neither of the introduced strains became a dominant member of the bacterial community. This work was the first approach to assess the establishment of plant growth promoting rhizobacteria and potential biocontrol agents on transgenic plants.
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Affiliation(s)
- Jana Lottmann
- Microbiology, Department of Biological Science, University of Rostock, Gertrudenstrasse 11a, D-18051 Rostock, Germany
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Krimsky S, Wrubel RP, Naess IG, Levy SB, Wetzler RE, Marshall B. Standardized Microcosms in Microbial Risk Assessment. Bioscience 1995. [DOI: 10.2307/1312763] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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13
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Бабич Л, Гарагуля А, Киприанова Е, Смирнов В, Шамрай С, Бабич Л, Гарагуля А, Киприанова Е, Смирнов В, Шамрай С, Babitch L, Garagulya A, Kiprianova E, Smirnov V, Shamray S. БАКТЕРИИ РОДА PSEUDOMONAS—АНТАГОНИСТЫ ВОЗБУДИТЕЛЯ КОРНЕВОЙ ГНИЛИ ЯРОВОГО ЯЧМЕНЯ. BIOTECHNOL BIOTEC EQ 1993. [DOI: 10.1080/13102818.1993.10819408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Suppression of Soil-Borne Plant Pathogens by Fluorescent Pseudomonads: Mechanisms and Prospects. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/b978-0-444-88728-3.50042-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Sivan A, Harman GE. Improved rhizosphere competence in a protoplast fusion progeny of Trichoderma harzianum. Microbiology (Reading) 1991. [DOI: 10.1099/00221287-137-1-23] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The level and pattern of rhizosphere competence of a strain of Trichoderma harzianum (1295-22) derived from fusing protoplasts of auxotrophic mutants of the prototrophic strains T12 and T95 were studied and compared with those of the original strains. Colonization of the rhizosphere by the three strains was tested after treating seeds of cotton and maize with conidia and planting them in soil at a constant moisture content. Propagules of the fungi were removed by a washing technique, Trichoderma spp. were isolated by plating serial dilutions on a selective medium, and individual strains were identified by their characteristic growth on differential media. Both strains T12 and T95 colonized the entire length of maize roots, but strain 1295-22 was more effective in colonizing the middle sections of the roots than either parental strain. All strains colonized cotton roots more poorly than maize roots; strains T12 and T95 were not detected on some root segments of this crop. Strain T95 was, however, found on the root tip, while T12 was absent from this root portion. Conversely, strain 1295-22 colonized all root sections of this crop, and its population levels were higher in the middle root portions than those of either parental strain.
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Affiliation(s)
| | - G. E. Harman
- Department of Horticultural Sciences, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA
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Survival and Distribution of Bacterial Population in The Rhizosphere of Inoculated Plants. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/s0166-2481(08)70218-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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17
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BÃ¥th E, Olsson S, Tunlid A. Growth of bacteria in the rhizoplane and the rhizosphere of rape seedlings. FEMS Microbiol Lett 1988. [DOI: 10.1111/j.1574-6968.1988.tb02702.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Jones JD, Gutterson N. An efficient mobilizable cosmid vector, pRK7813, and its use in a rapid method for marker exchange in Pseudomonas fluorescens strain HV37a. Gene 1987; 61:299-306. [PMID: 2833429 DOI: 10.1016/0378-1119(87)90193-4] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We describe the construction and utilization of a new mobilizable cosmid vector. Using this vector, mobilizable libraries of bacterial DNA can be efficiently made without a need for size fractionation of target DNA. The low stability of this vector in Pseudomonas fluorescens makes it useful in a rapid strategy, which is not dependent on plasmid incompatibility, for recombining transposon-induced mutations into the bacterial chromosome.
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Affiliation(s)
- J D Jones
- Advanced Genetic Sciences Inc., Oakland, CA 94608
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Loper JE, Haack C, Schroth MN. Population Dynamics of Soil Pseudomonads in the Rhizosphere of Potato (
Solanum tuberosum
L.). Appl Environ Microbiol 1985; 49:416-22. [PMID: 16346729 PMCID: PMC238418 DOI: 10.1128/aem.49.2.416-422.1985] [Citation(s) in RCA: 114] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhizosphere population dynamics of seven
Pseudomonas fluorescens
and
Pseudomonas putida
strains isolated from rhizospheres of various agricultural plants were studied on potato (
Solanum tuberosum
L.) in field soil under controlled environmental conditions. Rhizosphere populations of two strains (B10 and B4) were quantitatively related to initial seed piece inoculum levels when plants were grown at −0.3 bar matric potential. At a given inoculum level, rhizosphere populations of strain B4 were consistently greater than those of strain B10. In vivo growth curves on 4-cm root tip-proximal segments indicated that both strains grew at similar rates in the potato rhizosphere, but large populations of strain B10 were not maintained at 24°C after 7 h, whereas those of strain B4 were maintained for at least 40 h. Although both strains grew more rapidly in the rhizosphere at 24°C than at 12°C, their rhizosphere populations after seed piece inoculation were generally greater at 12 or 18°C, indicating that in vivo growth did not solely determine rhizosphere populations in these studies. In vitro osmotolerance of seven
Pseudomonas
strains (including strains B4 and B10) was correlated with their abilities to establish stable populations in the rhizosphere of potato. Stability of rhizosphere populations of the
Pseudomonas
strains studied here was maximized at low (i.e., 12°C) soil temperatures. These results indicate that
Pseudomonas
strains differ in their capacity to maintain stable rhizosphere populations in association with potato. This capacity, distinct from the ability to grow in the rhizosphere, may limit the establishment of rhizosphere populations under some environmental conditions.
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Affiliation(s)
- J E Loper
- Department of Plant Pathology, University of California, Berkeley, California 94720
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