scholarly journals Root Microbiome Modulates Plant Growth Promotion Induced by Low Doses of Glyphosate

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Dario X. Ramirez-Villacis ◽  
Omri M. Finkel ◽  
Isai Salas-González ◽  
Connor R. Fitzpatrick ◽  
Jeffery L. Dangl ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Growth Inhibition ◽  
Growth Promotion ◽  
Action Spectrum ◽  
Dry Weight ◽  
Agricultural Fields ◽  
Low Doses ◽  
Shoot Dry Weight ◽  
Root Microbiome

ABSTRACT Glyphosate is a commonly used herbicide with a broad action spectrum. However, at sublethal doses, glyphosate can induce plant growth, a phenomenon known as hormesis. Most glyphosate hormesis studies have been performed under microbe-free or reduced-microbial-diversity conditions; only a few were performed in open systems or agricultural fields, which include a higher diversity of soil microorganisms. Here, we investigated how microbes affect the hormesis induced by low doses of glyphosate. To this end, we used Arabidopsis thaliana and a well-characterized synthetic bacterial community of 185 strains (SynCom) that mimics the root-associated microbiome of Arabidopsis. We found that a dose of 3.6 × 10−6 g acid equivalent/liter (low dose of glyphosate, or LDG) produced an ∼14% increase in the shoot dry weight (i.e., hormesis) of uninoculated plants. Unexpectedly, in plants inoculated with the SynCom, LDG reduced shoot dry weight by ∼17%. We found that LDG enriched two Firmicutes and two Burkholderia strains in the roots. These specific strains are known to act as root growth inhibitors (RGI) in monoassociation assays. We tested the link between RGI and shoot dry weight reduction in LDG by assembling a new synthetic community lacking RGI strains. Dropping RGI strains out of the community restored growth induction by LDG. Finally, we showed that individual RGI strains from a few specific phyla were sufficient to switch the response to LDG from growth promotion to growth inhibition. Our results indicate that glyphosate hormesis was completely dependent on the root microbiome composition, specifically on the presence of root growth inhibitor strains. IMPORTANCE Since the introduction of glyphosate-resistant crops, glyphosate has become the most common and widely used herbicide around the world. Due to its intensive use and ability to bind to soil particles, it can be found at low concentrations in the environment. The effect of these remnants of glyphosate in plants has not been broadly studied; however, glyphosate 1,000 to 100,000 times less concentrated than the recommended field dose promoted growth in several species in laboratory and greenhouse experiments. However, this effect is rarely observed in agricultural fields, where complex communities of microbes have a central role in the way plants respond to external cues. Our study reveals how root-associated bacteria modulate the responses of Arabidopsis to low doses of glyphosate, shifting between growth promotion and growth inhibition.

scholarly journals Plant growth promoting rhizobacteria and their potential as bioinoculants on Pennisetum clandestinum (Poaceae)

2019 ◽  
Vol 67 (4) ◽  
Author(s):  
Felipe Romero-Perdomo ◽  
Jhonnatan Ocampo-Gallego ◽  
Mauricio Camelo-Rusinque ◽  
Ruth Bonila
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Dry Weight ◽  
Shoot Length ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Pennisetum Clandestinum ◽  
Shoot Dry Weight ◽  
Root And Shoot Length

In this study, we aimed at examining the potential to stimulate growth in Pennisetum clandestinum using four isolated bacterial strains from soils obtained from a Colombian tropical silvopastoral system. We previously identified genetically the strains and characterized two plant growth promotion activities. We found that the four bacterial strains were phylogenetically associated with Klebsiella sp. (strains 28P and 35P), Beijerinka sp. (37L) and Achromobacter xylosoxidans (E37), based on partial 16S rRNA gene sequencing. Moreover, the in vitro biochemical assays demonstrated that the strains exhibited some plant growth promotion mechanisms such as 1-aminocyclopropane-1-carboxylic acid deaminase activity and indole compound synthesis. Notably, bacterial inoculation under greenhouse conditions showed a positive influence on P. clandestinum growth. We found a significant (p < 0.05) effect on root and shoot length, and shoot dry weight. Shoot length increased by 52% and 30% with 37L and 35P, respectively, compared to those without inoculation treatment. Similarly, the use of 37L and 28P raised shoot dry weight values by 170% and 131%, respectively. In root development, inoculation with strains 37L and E37 increased root length by 134% and 100%, respectively. Beijerinckia sp. 37L was the most effective of the four strains at increasing P. clandestinum biomass and length.

Characterization of Mesorhizobium strains for salt tolerance and wilt control: Their potential for plant growth promotion of chickpea (Cicer arietinum L.)

2018 ◽  
Author(s):  
Anju Sehrawat ◽  
Aakanksha Khandelwal ◽  
Satyavir Singh Sindhu
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Fusarium Wilt ◽  
Biocontrol Agent ◽  
Growth Promotion ◽  
Dry Weight ◽  
Antagonistic Effect ◽  
Maximum Increase ◽  
Shoot Dry Weight ◽  
Plant Growth Promoting

Mesorhizobium sp. indirectly promote the growth of plants as a biocontrol agent by inhibiting the growth of pathogens particularly Fusarium wilt of chickpea. Out of 24 Mesorhizobium isolates obtained from chickpea nodules, eight isolates showed antagonistic effect against Fusarium oxysporum. Salinity stress severely affects growth, nodulation and yield of chickpea. Mesorhizobium isolates were tested for their salt tolerance capacity at 1, 2, 4, 6 and 8% NaCl concentrations. Only two Mesorhizobium isolates MCA5 and MCA22 were found salt-tolerant upto 8% of salt concentration. Maximum increase (45.5%) in shoot dry weight was observed by inoculation of isolate MCA20 at 40 days of chickpea growth under chillum jar conditions, whereas isolate MCA23 resulted in 166.2% increase in root dry weight. Likewise, 112.6% increase in shoot dry weight was observed on inoculation of MCA14 isolate at 80th day of observation. Further extensive research is required to understand the mechanism of potential Mesorhizobium isolates of chickpea in controlling Fusarium wilt disease and salt tolerance. Selection of mesorhizobia with twin functional traits (plant growth promoting and biocontrol agent) can be exploited as future biofertilizer in chickpea.

scholarly journals Enhanced growth of cabbage seedlings by a Paenibacillus isolate in the presence of Xanthomonas campestris pv campestris

2015 ◽  
Vol 68 ◽  
pp. 173-178
Author(s):  
H. Ghazalibiglar ◽  
J.G. Hampton ◽  
E. van_Zijll De_Jong ◽  
A. Holyoake
Keyword(s):  
Plant Growth ◽  
Xanthomonas Campestris ◽  
Growth Promotion ◽  
Growth Parameters ◽  
Dry Weight ◽  
Positive Control ◽  
Negative Control ◽  
Disease Suppression ◽  
Shoot Dry Weight ◽  
Promote Plant Growth

Paenibacillus spp are rhizobacteria that can promote plant growth through a range of mechanisms A New Zealand isolate of Paenibacillus P16 has reduced the incidence of black rot caused by Xanthamonas campestris pv campestris (Xcc) in brassicas To investigate if this response was provided through plant growth promotion isolate P16 was coapplied with Xcc as a seed treatment In the presence of Xcc P16treated seedlings had significantly greater root length leaf area and root and shoot dry weight compared to the positive control (Xcc alone) There were no significant differences in plant growth parameters between P16treated seedlings in the absence of the pathogen and the negative control (seeds without Xcc or P16) Isolate P16 enabled plants to survive and grow normally by preventing disease development; the mechanism of disease suppression requires further investigation

scholarly journals Rhizobacterial Inoculants Increase Root and Shoot Growth in ‘Tifway’ Hybrid Bermudagrass

2014 ◽  
Vol 32 (3) ◽  
pp. 149-154 ◽  
Author(s):  
R. Murphey Coy ◽  
David W. Held ◽  
Joseph W. Kloepper
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Growth Promotion ◽  
Dry Weight ◽  
Plant Growth Promoting Rhizobacteria ◽  
Bacterial Strains ◽  
Agronomic Crops ◽  
Plant Growth Promoting ◽  
Bacterial Treatment ◽  
Growth Promoting

Plant growth-promoting rhizobacteria (PGPR) are non-pathogenic, beneficial bacteria that colonize seeds and roots of plants and enhance plant growth. Although there has been extensive PGPR research with agronomic crops, there has been little emphasis on development of PGPR for grasses in pastures or as turf. Accordingly, experiments were conducted to evaluate novel bacterial inoculants for growth promotion in ‘Tifway’ hybrid bermudagrass. Replicated laboratory and greenhouse experiments evaluated effects of various PGPR mixtures, each with 3 to 5 PGPR strains and applied as weekly root inoculations, in comparison to nontreated plants. Growth promotion was assessed by measuring foliar growth from 3 to 8 wk and root growth at 8 wk after the first treatment. In all experiments, at least one bacterial treatment of bermudagrass resulted in significantly increased top growth and greater root growth (length, surface area, volume, or dry weight). PGPR blends 20 and MC3 caused the greatest growth promotion of roots and shoots. These results suggest that the bacterial strains could be used in strategies to reduce nitrogen or water inputs to turf.

scholarly journals Applications of plant growth promoting bacteria and Trichoderma spp. for controlling Orobanche crenata in faba bean

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
Mahmoud Ahmed Touny El-Dabaa ◽  
Hassan Abd-El-Khair
Keyword(s):  
Plant Growth ◽  
Faba Bean ◽  
Growth Parameters ◽  
Dry Weight ◽  
Research Centre ◽  
Plant Growth Promoting Bacteria ◽  
Fresh Weight ◽  
Orobanche Crenata ◽  
Trichoderma Spp ◽  
Shoot Dry Weight

Abstract Background Orobanche crenata is an obligate root parasite belonging to Orbanchaceae. Broomrape causes great damage to the faba bean. Several attempts were applied for controlling parasitic weeds. So, the aim of this work is to study the application of Trichoderma spp. as well as three rhizobacteria species in comparison to herbicidal effect of Glyphosate (Glialka 48% WSC) for controlling broomrape infesting faba bean (Vicia faba). Materials and methods Three pot experiments were carried out in the greenhouse of the National Research Centre, Dokki, Giza, Egypt during two successive winter seasons. Trichoderma inocula were adjusted to 3.6 × 108 propagules/ml and the bacterium inocula were adjusted at 107–109 colony-forming unit (CFU)/ml. All treatments were applied, before 1 week of sowing, at rate of 50 ml per pot in experiments I and II, while 100 ml per pot in experiment III. Results Trichoderma spp. (T. harzianum, T. viride and T. vierns) as well as three rhizobacteria species (Pseudomonas fluorescens, Bacillus subtilis and Bacillus pumilus) enhanced the growth parameters in faba bean plants, i.e. shoot length, shoot fresh weight, shoot dry weight and leaf number in the first experiment when applied without O. crenata infection. In the second experiment, all bio-control could protect plants against O. crenata infection, where it had better juvenile number reduction, than glyphosate after 2 months of application. Both B. subtilis and B. pumilus had the highest reduction to juvenile fresh weight, while their effect was equal to herbicide for juvenile dry weight, respectively. The bio-control agents had high effects until the 4th month, but it was less than that of the herbicide. In experiment III, the bio-control agents could highly reduce the juvenile parameters after 2 months, as well as juvenile fresh weight and juvenile dry weight after 4 months, than the herbicide, respectively. The bio-control agents were effective until 6 months, but less than the herbicide effect. All bio-control treatments highly increased the plant growth parameters, than the herbicide. Conclusion The application of Trichoderma spp. as well as rhizobacteria species could play an important role in controlling broomrape in faba bean as a natural bioherbicide.

scholarly journals Isolation and Characterization of Nodule-AssociatedExiguobacterium sp. from the Root Nodules ofFenugreek(Trigonella foenum-graecum) and Their Possible Role in Plant Growth Promotion

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Geetha Rajendran ◽  
Maheshwari H. Patel ◽  
Sanket J. Joshi
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Root Nodules ◽  
Dry Weight ◽  
Gram Positive ◽  
Associated Bacteria ◽  
Trigonella Foenum Graecum ◽  
Isolation And Characterization ◽  
Root And Shoot Length

One of the ways to increase the competitive survivability of rhizobial biofertilizers and thus achieve better plant growth under such conditions is by modifying the rhizospheric environment or community by addition of nonrhizobial nodule-associated bacteria (NAB) that cause better nodulation and plant growth when coinoculated with rhizobia. A study was performed to investigate the most commonly associated nodule-associated bacteria and the rhizospheric microorganisms associated with theFenugreek(Trigonella foenum-graecum) plant. Isolation of nonrhizobial isolates from root nodules ofFenugreekwas carried out along with the rhizospheric isolates. About 64.7% isolates obtained fromFenugreeknodules were gram-negative coccobacilli, 29.41% were gram-positive bacilli, and all rhizospheric isolates except one were gram-positive bacilli. All the isolates were characterized for their plant growth promoting (PGP) activities. Two of the NAB isolates M2N2c and B1N2b (Exiguobacterium sp.) showed maximum positive PGP features. Those NAB isolates when coinoculated with rhizobial strain—S. meliloti, showed plant growth promotion with respect to increase in plant’s root and shoot length, chlorophyll content, nodulation efficiency, and nodule dry weight.

scholarly journals The Root Endophytic Fungus Serendipita indica Decreased the Phytotoxicity of Zinc Oxide Nanoparticles to Alfalfa (Medicago sativa L.)

2021 ◽  
Author(s):  
Leila Tabande ◽  
Mozhgan Sepehri ◽  
Jafar Yasrebi ◽  
Mehdi Zarei ◽  
Reza Ghasemi-Fasaei ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Plant Growth ◽  
Zinc Oxide Nanoparticles ◽  
Sinorhizobium Meliloti ◽  
Dry Weight ◽  
Oxide Nanoparticles ◽  
Zno Nps ◽  
Shoot Dry Weight ◽  
Nano Zinc Oxide ◽  
Nano Zinc

Abstract Zinc oxide nanoparticles (ZnO-NPs) are among the most commonly used nano-fertilizers (NF). However, elevated levels of ZnO-NPs in soil may affect plant growth and development due to its potential toxicity when accumulated in large amounts in plant tissues. This research was conducted using an in situ rhizobox system with the aims of evaluating Zinc uptake from nano-zinc oxide amended rhizosphere soil by alfalfa plant and the effect of plant growth promoting microorganisms on alleviating the phytotoxicity of ZnO-NPs. Treatments included microbial inoculations (Sinorhizobium meliloti, Serendipita indica) and different ZnO-NPs concentrations (0, 400 and 800 mg Kg− 1) with three replications. The results indicated that S. indica minimized the phytotoxicity of ZnO-NPs to alfalfa by enhancing growth rate and decreasing Zinc (Zn) translocation from root to shoot. Compared with plants inoculated with S. meliloti, co-inoculation with S. indica increased the shoot dry weight by 18.33% and 8.05% at 400 and 800 mg Kg− 1ZnO-NPs. However, at the highest level of ZnO-NPs (800 mg kg− 1), root inoculation of S. indica and S. indica + S. meliloti decreased Zn transfer factor by 60.2% and 44.3% compared to S. meliloti, respectively. Furthermore, a distinct relation between tolerance of S. indica-colonized plant to ZnO-NPs and the ability of S. indica in inhibiting or retarding degradation of polyunsaturated lipids through prevention of excess reactive oxygen species formation was observed. Malondialdehyde content of inoculated plants with S. indica either alone or in combination with S. meliloti was significantly lower than non-inoculated plants (p < 0.01). Zn-induced oxidative stress was mitigated by S. indica through enhanced activities of catalase and peroxidase enzymes. The findings of the present study indicate the potential use of endophytes fungus S. indica for ensuring food safety and security, and human health in heavy metal–polluted soil by reducing the phytoavailability of heavy metals in the aerial parts of the host plants.

scholarly journals Evaluation of a Substrate-applied Humectant to Mitigate Drought Stress in Young, Container-grown Plants

2015 ◽  
Vol 33 (3) ◽  
pp. 137-141
Author(s):  
Bruce R. Roberts ◽  
Chris Wolverton ◽  
Samantha West
Keyword(s):  
Drought Stress ◽  
Root Growth ◽  
Shoot Growth ◽  
Dry Weight ◽  
Root:Shoot Ratio ◽  
Xylem Water Potential ◽  
Bedding Plants ◽  
Shoot Dry Weight ◽  
Soilless Substrate ◽  
Absorbing Roots

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.

scholarly journals Isolation and Characterization of Phosphate-Solubilizing Bacteria from Mushroom Residues and their Effect on Tomato Plant Growth Promotion

2017 ◽  
Vol 66 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Jian Zhang ◽  
Peng Cheng Wang ◽  
Ling Fang ◽  
Qi-An Zhang ◽  
Cong Sheng Yan ◽  
...  
Keyword(s):  
Plant Growth ◽  
Growth Promotion ◽  
Wood Flour ◽  
Dry Weight ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Phosphate Solubilizing Bacteria ◽  
Sequence Comparisons ◽  
Isolation And Characterization ◽  
Phosphate Solubilizing

Phosphorus is a major essential macronutrient for plant growth, and most of the phosphorus in soil remains in insoluble form. Highly efficient phosphate-solubilizing bacteria can be used to increase phosphorus in the plant rhizosphere. In this study, 13 isolates were obtained from waste mushroom residues, which were composed of cotton seed hulls, corn cob, biogas residues, and wood flour. NBRIP solid medium was used for isolation according to the dissolved phosphorus halo. Eight isolates produced indole acetic acid (61.5%), and six isolates produced siderophores (46.2%). Three highest phosphate-dissolving bacterial isolates, namely, M01, M04, and M11, were evaluated for their beneficial effects on the early growth of tomato plants (Solanum lycopersicum L. Wanza 15). Strains M01, M04, and M11 significantly increased the shoot dry weight by 30.5%, 32.6%, and 26.2%, and root dry weight by 27.1%, 33.1%, and 25.6%, respectively. Based on 16S rRNA gene sequence comparisons and phylogenetic positions, strains M01 and M04 belonged to the genus Acinetobacter, and strain M11 belonged to the genus Ochrobactrum. The findings suggest that waste mushroom residues are a potential resource of plant growth-promoting bacteria exhibiting satisfactory phosphate-solubilizing for sustainable agriculture.

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