Biological nitrogen fixation and plant growth promotion of lodgepole pine by an endophytic diazotroph Paenibacillus polymyxa and its GFP-tagged derivative

Botany ◽  
2017 ◽  
Vol 95 (6) ◽  
pp. 611-619 ◽  
Author(s):  
Qian Tang ◽  
Akshit Puri ◽  
Kiran Preet Padda ◽  
Chris P. Chanway
Keyword(s):  
Plant Growth ◽  
Seedling Growth ◽  
Fluorescent Protein ◽  
Growth Promotion ◽  
Lodgepole Pine ◽  
Paenibacillus Polymyxa ◽  
Growth Enhancement ◽  
Plant Growth Promoting ◽  
Green Fluorescent ◽  
Biological Nitrogen

Paenibacillus polymyxa P2b-2R is an endophytic diazotroph originally isolated from lodgepole pine. It is reported to fix significant amounts of nitrogen (N) and promote plant growth. To evaluate the endophytic colonization sites, a green fluorescent protein (GFP) derivative of P2b-2R was generated (P2b–2Rgfp), but the effects of GFP modification on the functioning of P2b-2R have not been fully elucidated yet. In this study, we wanted to confirm and contrast the N-fixing and plant-growth-promoting abilities of P2b-2Rgfp with those of the wild-type P2b-2R in lodgepole pine. Pine seedlings were grown in an N-limited environment and harvested 2, 4, 8, and 12 months after inoculation to evaluate the endophytic and rhizospheric colonization by both strains, the amount of N-fixed, and seedling growth enhancement. Both P2b-2R and P2b-2Rgfp strains formed persistent rhizospheric and endophytic populations; fixed N; and enhanced seedling growth continuously after 4 months. P2b-2Rgfp-treated seedlings outperformed the P2b-2R-treated seedlings in terms of biomass only during the initial stages of plant development, but the differences decreased during the trial and were not significant towards the end. To the best of our knowledge, this is the first study that reports the effects of GFP-tagging of an endophyte when inoculated into a gymnosperm tree species.

N2-Fixation and Seedling Growth Promotion of Lodgepole Pine by Endophytic Paenibacillus polymyxa

2013 ◽  
Vol 66 (2) ◽  
pp. 369-374 ◽  
Author(s):  
Richa Anand ◽  
Susan Grayston ◽  
Christopher Chanway
Keyword(s):  
Seedling Growth ◽  
N2 Fixation ◽  
Growth Promotion ◽  
Lodgepole Pine ◽  
Paenibacillus Polymyxa

Colonization and growth promotion of outplanted spruce seedlings pre-inoculated with plant growth-promoting rhizobacteria in the greenhouse

2000 ◽  
Vol 30 (6) ◽  
pp. 845-854 ◽  
Author(s):  
Masahiro Shishido ◽  
Christopher P Chanway
Keyword(s):  
Plant Growth ◽  
Seedling Growth ◽  
Picea Glauca ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Population Declines ◽  
Growth Responses ◽  
Relative Growth Rates ◽  
Plant Growth Promoting ◽  
Growth Promoting

Seeds of two hybrid spruce (Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm.) ecotypes were inoculated with one of six plant growth-promoting rhizobacteria (PGPR) strains previously shown to be able to stimulate spruce growth in controlled environments. The resulting seedlings were grown in the greenhouse for 17 weeks before outplanting at four reforestation sites. Inoculation with five of the six strains caused significant seedling growth promotion in the greenhouse, which necessitated analysis of relative growth rates (RGR) to evaluate seedling performance in the field. Four months after outplanting, most strains enhanced spruce shoot or root RGRs in the field, but seedling growth responses were strain specific. For example, Pseudomonas strain Ss2-RN significantly increased both shoot and root RGRs by 10-234% at all sites, but increases of 28-70% were most common. In contrast, Bacillus strain S20-R was ineffective at all outplanting sites. In addition, seedlings inoculated with four of the six strains had significantly less shoot injury than control seedlings at all sites. Evaluation of root colonization by PGPR indicated that bacterial population declines were not related to spruce growth response variability in the field. Our results indicate that once plant growth promotion is induced in the greenhouse, seedling RGR can increase by more than 100% during the first growing season in the field. However RGR increases of 21-47% were more common and may be more representative of the magnitude of biomass increases that can result from PGPR inoculation.

scholarly journals Paenibacillus polymyxa Invades Plant Roots and Forms Biofilms

2005 ◽  
Vol 71 (11) ◽  
pp. 7292-7300 ◽  
Author(s):  
Salme Timmusk ◽  
Nina Grantcharova ◽  
E. Gerhart H. Wagner
Keyword(s):  
Plant Growth ◽  
Fluorescent Protein ◽  
Paenibacillus Polymyxa ◽  
Plant Roots ◽  
Root Tip ◽  
Broad Host Range ◽  
Plant Growth Promoting Bacteria ◽  
Soil System ◽  
Plant Growth Promoting ◽  
Growth Promoting

ABSTRACT Paenibacillus polymyxa is a plant growth-promoting rhizobacterium with a broad host range, but so far the use of this organism as a biocontrol agent has not been very efficient. In previous work we showed that this bacterium protects Arabidopsis thaliana against pathogens and abiotic stress (S. Timmusk and E. G. H. Wagner, Mol. Plant-Microbe Interact. 12:951-959, 1999; S. Timmusk, P. van West, N. A. R. Gow, and E. G. H. Wagner, p. 1-28, in Mechanism of action of the plant growth promoting bacterium Paenibacillus polymyxa, 2003). Here, we studied colonization of plant roots by a natural isolate of P. polymyxa which had been tagged with a plasmid-borne gfp gene. Fluorescence microscopy and electron scanning microscopy indicated that the bacteria colonized predominantly the root tip, where they formed biofilms. Accumulation of bacteria was observed in the intercellular spaces outside the vascular cylinder. Systemic spreading did not occur, as indicated by the absence of bacteria in aerial tissues. Studies were performed in both a gnotobiotic system and a soil system. The fact that similar observations were made in both systems suggests that colonization by this bacterium can be studied in a more defined system. Problems associated with green fluorescent protein tagging of natural isolates and deleterious effects of the plant growth-promoting bacteria are discussed.

The growth-promoting effects of a bacterial endophyte on lodgepole pine are partially inhibited by the presence of other rhizobacteria

1998 ◽  
Vol 44 (10) ◽  
pp. 980-988 ◽  
Author(s):  
Elizabeth Bent ◽  
Christopher P Chanway
Keyword(s):  
Plant Growth ◽  
Growth Promotion ◽  
Lodgepole Pine ◽  
Primary Root ◽  
Biomass Accumulation ◽  
Plant Growth Promoting Rhizobacteria ◽  
Shoot Biomass ◽  
Bacillus Polymyxa ◽  
Plant Growth Promoting ◽  
Growth Promoting

To test the hypothesis that rhizobacteria naturally present in soils may interfere with the extent of root colonization and plant growth promotion by plant growth-promoting rhizobacteria (PGPR), we studied two lodgepole pine PGPR (Bacillus polymyxa strains L6 and Pw-2) when inoculated singly and when coinoculated with a non-PGPR competitor (Curtobacterium flaccumfaciens PF322). Bacillus polymyxa Pw-2 and Curtobacterium flaccumfaciens PF322 were consistently found as endophytes, while Bacillus polymyxa L6 was never found within the root interior. Strains Pw-2 and L6 differed in the rate and type of growth promotion. Strain Pw-2 increased root growth (branching and elongation) and shoot biomass accumulation 6 and 9 weeks, respectively, after inoculation, while strain L6 increased primary root elongation and root biomass accumulation after 12 weeks. Seedlings coinoculated with Pw-2 and PF322 had decreased shoot biomass and primary root lengths when compared with seedlings inoculated only with Pw-2. This effect was not linked to a decrease in the population size of Pw-2 in the rhizosphere or in the root interior of coinoculated treatments. In contrast, strain L6-mediated growth promotion was not impaired by coinoculation with PF322. Strain L6 did interfere to some degree with the growth-promoting capability of strain Pw-2. These results indicate that endophytic PGPR may be less adapted to microbial competition than external root-colonizing PGPR, and that the efficacy of endophytic PGPR may be reduced by the presence of other bacteria on external or internal root tissues.Key words: PGPR, endophytes, colonization, coinoculation, competition.

scholarly journals Comparison of Benefit to Sugarcane Plant Growth and 15N2 Incorporation Following Inoculation of Sterile Plants with Acetobacter diazotrophicus Wild-Type and Nif¯ Mutant Strains

2001 ◽  
Vol 14 (3) ◽  
pp. 358-366 ◽  
Author(s):  
Myrna Sevilla ◽  
Robert H. Burris ◽  
Nirmala Gunapala ◽  
Christina Kennedy
Keyword(s):  
Plant Growth ◽  
Growth Promotion ◽  
Growth Enhancement ◽  
Wild Type ◽  
Acetobacter Diazotrophicus ◽  
Sugarcane Plant ◽  
Total N ◽  
Mutant Strains ◽  
Plant Growth Promoting ◽  
Significant Mechanism

The ability of the nitrogen-fixing bacterial endophyte Acetobacter diazotrophicus strain PAl5 to enhance the growth of sugarcane SP70-1143 was evaluated in the growth chamber, greenhouse, and field by comparing plants inoculated with wild-type and Nif¯ mutant MAd3A in two independent experiments. The wild-type and Nif¯ mutant strains colonized sugarcane plants equally and persisted in mature plants. In N-deficient conditions, sugarcane plants inoculated with A. diazotrophicus PAl5 generally grew better and had a higher total N content 60 days after planting than did plants inoculated with mutant MAd3A or uninoculated plants. These results indicate that the transfer of fixed N from A. diazotrophicus to sugarcane might be a significant mechanism for plant growth promotion in this association. When N was not limiting, growth enhancement was observed in plants inoculated with either wild-type or Nif¯ mutants, suggesting the additional effect of a plant growth promoting factor provided by A. diazotrophicus. A 15N2 incorporation experiment demonstrated that A. diazotrophicus wild-type strains actively fixed N2 inside sugarcane plants, whereas the Nif¯ mutants did not.

Spruce growth response specificity after treatment with plant growth-promoting Pseudomonads

1999 ◽  
Vol 77 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Masahiro Shishido ◽  
Christopher P Chanway
Keyword(s):  
British Columbia ◽  
Plant Growth ◽  
Seedling Growth ◽  
Picea Glauca ◽  
Forest Floor ◽  
Growth Promotion ◽  
Geographical Area ◽  
Seed Collection ◽  
Plant Growth Promoting ◽  
Growth Promoting

Naturally regenerating hybrid spruce seedlings (Picea glauca (Moench) Voss beta Picea engelmannii Parry) were collected from sites near Mackenzie, Salmon Arm, and Williams Lake, British Columbia, Canada. Bacteria were isolated from roots and screened in greenhouse trials for their ability to enhance spruce growth. Three strains belonging to the genus Pseudomonas were selected for study based on their disparate geographic origins and their capacity to consistently stimulate spruce seedling growth in screening trials. Factorial experiments were performed in the greenhouse to evaluate the effectiveness of these Pseudomonas strains with different spruce ecotypes. Factors tested were spruce seed sources, Pseudomonas isolates, and forest floor soils originating from different sites. Three levels of each factor were studied: one spruce seedlot, one Pseudomonas isolate, and one forest floor type each originated from a site at Mackenzie, Salmon Arm, and Williams Lake, British Columbia. Fourteen weeks after treatments were established, spruce biomass accumulation was greatest when spruce ecotypes were inoculated with bacteria originating from the same geographical area as spruce seed. However, Pseudomonas strains originating from sites other than the seed collection area also stimulated seedling growth significantly, rendering the difference in growth promotion between bacterial treatments small and insignificant. In addition, spruce growth promotion was not enhanced when seed was treated with combinations of Pseudomonas strains and forest floor soils originating from the same forest ecosystem. We conclude that specificity between spruce ecotypes and plant growth-promoting rhizobacteria strains can be detected under carefully controlled conditions, thereby supporting the hypothesis that growth-promoting bacteria may adapt to their plant hosts. However, the growth advantage accruing to seedlings treated with bacteria originating from the same ecosystem is small and suggests that it is not necessary to match Pseudomonas strains with spruce ecotypes and soil types for effective seedling growth promotion.Key words: Pseudomonas, spruce, specificity, growth promotion.

scholarly journals Quantifying Plant-Borne Carbon Assimilation by Root-Associating Bacteria

2020 ◽  
Vol 8 (5) ◽  
pp. 700 ◽  
Author(s):  
Spenser Waller ◽  
Stacy L. Wilder ◽  
Michael J. Schueller ◽  
Alexandra B. Housh ◽  
Richard A. Ferrieri
Keyword(s):  
Plant Growth ◽  
Fluorescent Protein ◽  
Growth Promotion ◽  
Carbon Assimilation ◽  
Microbial Colonization ◽  
Fluorescence Measurement ◽  
Grass Root ◽  
Promote Plant Growth ◽  
The One ◽  
Green Fluorescent

Herbaspirillum seropedicae is a rhizobacteria that occupies a specialized ecological niche in agriculture. As an endophyte and prolific grass root colonizer it has the potential to promote plant growth, enhancing crop yield in many cereal crops. While the mechanisms for plant growth promotion are controversial, the one irrefutable fact is these microorganisms rely heavily on plant-borne carbon as their main energy source in support of their biological functions. Unfortunately, the tools and technology enabling researchers to trace carbon exchange between plants and the microorganisms associating with them has been limiting. Here, we demonstrate that radioactive 11CO2 administered to intact maize leaves with translocation of 11C-photosynthates to roots can provide a ‘traceable’ source of carbon whose assimilation by microbial organisms can be quantified with enormous sensitivity. Fluorescence root imaging of RAM10, a green fluorescent protein (GFP) reporting strain of H. seropedicae, was used to identify regions of high microbial colonization. Microbes were mechanically removed from these regions via sonication in saline solution and extracts were subjected to fluorescence measurement and gamma counting to correlate carbon-11 atoms with numbers of colony forming units. The method has potential to translate to other microorganisms provided they possess an optical reporting trait.

scholarly journals Effect of Penicillium Extractsa on Germination Vigor in Subsequent Seedling Growth of Tomato (Solanum Lycopersicum L.)

2014 ◽  
Vol 65 (1) ◽  
pp. 71-77
Author(s):  
Ghazala Nasim ◽  
Sobia Mushtaq ◽  
Irum Mukhtar ◽  
Ibatsam Khokhar
Keyword(s):  
Plant Growth ◽  
Seedling Growth ◽  
Growth Promotion ◽  
Tomato Seedling ◽  
Growth And Survival ◽  
Tomato Seedlings ◽  
Solanum Lycopersicum L ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Germination Vigor

AbstractPenicilliumspp. are well known to produce a variety of beneficial metabolites for plant growth and survival, as well as defend their hosts from attack of certain pathogens. In this study, effects of culture filtrate of differentPenicilliumspp. were tested on tomato seeds. On the whole, presoaking of seeds in filtrates of the ninePenicilliumisolates tested, significantly increased seed germination when compared with the control seeds. Cultural extracts ofP. expensumandP. billiwere highly effective in growth promotion up to 90%. It was also observed thatP. implicatumandP. oxlalicamsignificantly enhanced the root growth in tomato seedling as compare to other species. In case of shoot length,P. verrucosum(3.38),P. granulatum(2.81) andP. implicatum(2.62) were effective. HoweverP. implicatumwas quite promising to increase shoot and root length in tomato seedlings. Where asP. simplicissimiumandP. citrinumwere leas effective on seedling growth. The plant growth promoting ability ofPenicilliumstrains may help in growth permotion in other plants and crops.Penicilliumspp. are already known for producing mycotoxin and enzymes. Plant growth promoting ability ofPenicilliumspp will open new aspects of research and investigations. The role ofPenicil-liumspp. in tomato plant growth requires further exploration.

Alterations in plant growth and in root hormone levels of lodgepole pines inoculated with rhizobacteria

2001 ◽  
Vol 47 (9) ◽  
pp. 793-800 ◽  
Author(s):  
Elizabeth Bent ◽  
Sadik Tuzun ◽  
Christopher P Chanway ◽  
Scott Enebak
Keyword(s):  
Plant Growth ◽  
Pseudomonas Fluorescens ◽  
Pinus Contorta ◽  
Growth Promotion ◽  
Lodgepole Pine ◽  
Plant Root ◽  
Lateral Roots ◽  
Bacterial Species ◽  
Paenibacillus Polymyxa ◽  
Hormone Levels

The presence of other soil microorganisms might influence the ability of rhizobacterial inoculants to promote plant growth either by reducing contact between the inoculant and the plant root or by interfering with the mechanism(s) involved in rhizobacterially mediated growth promotion. We conducted the following experiments to determine whether reductions in the extent of growth promotion of lodgepole pine mediated by Paenibacillus polymyxa occur in the presence of a forest soil isolate (Pseudomonas fluorescens M20) and whether changes in plant growth promotion mediated by P. polymyxa (i) are related to changes in P. polymyxa density in the rhizosphere or (ii) result from alterations in root hormone levels. The extent of plant growth, P. polymyxa rhizosphere density, and root hormone concentrations were determined for lodgepole pine treated with (i) a single growth-promoting rhizobacterial strain (P. polymyxa L6 or Pw-2) or (ii) a combination of bacteria: strain L6 + strain M20 or strain Pw-2 + strain M20. There was no difference in the growth of pines inoculated with strain L6 and those inoculated with strain L6 + strain M20. However, seedlings inoculated with strain Pw-2 had more lateral roots and greater root mass at 12 weeks after inoculation than plants inoculated with strain Pw-2 + strain M20. The extent of growth promotion mediated by P. polymyxa L6 and Pw-2 in each treatment was not correlated to the average population density of each strain in the rhizosphere. Bacterial species-specific effects were observed in root hormone levels: indole-3-acetic acid concentration was elevated in roots inoculated with P. polymyxa L6 or Pw-2, while dihydrozeatin riboside concentration was elevated in roots inoculated with P. fluorescens M20.Key words: PGPR, Pinus contorta, Pseudomonas fluorescens, Paenibacillus polymyxa, auxin, cytokinin.

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