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

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.

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Effect of Plant Growth Promoting Bacillus spp. on Germination and Seedling Growth of Soybean

Legume Research - An International Journal ◽

10.18805/lrf-665 ◽

2022 ◽

Author(s):

D. Miljaković ◽

J. Marinković ◽

G. Tamindžić ◽

V. Đorđević ◽

M. Ignjatov ◽

...

Keyword(s):

Plant Growth ◽

Dry Weight ◽

Macrophomina Phaseolina ◽

Phytopathogenic Fungi ◽

Antagonistic Effect ◽

Vegetable Crops ◽

Bacterial Isolates ◽

Shoot Dry Weight ◽

Bacillus Spp ◽

Plant Growth Promoting

Background: Bacillus spp., known to promote growth and reduce disease of various field and vegetable crops, are frequently found in soils. The objective of the study was to select effective Bacillus spp. isolates with multiple plant growth properties and antifungal activities and to examine their effect on germination of soybean. Methods: Bacterial isolates were screened for production of indole-3-acetic acid (IAA) and siderophores and solubilization of phosphate. The ability of bacterial isolates to inhibit the growth of seven phytopathogenic fungi affecting soybean was determined using a dual plate assay. Bacillus spp. were further selected and examined in a seed germination test. Result: All Bacillus spp. isolates were positive for IAA production, while siderophore production and P-solubilization were observed in 80% and 20% bacterial isolates, respectively. Bacillus spp. exhibited the highest antifungal activity against Diaporthe caulivora, followed by Diaporthe sojae, Diaporthe eres, Diaporthe longicolla and Macrophomina phaseolina and the least antagonistic effect toward Fusarium graminearum and Fusarium subglutinans. Selected isolates of B. subtilis significantly affected final germination, shoot length, root length, shoot dry weight and root dry weight of two soybean cultivars. The most effective Bacillus spp. isolates could be used as potential inoculants for improving soybean productivity.

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Effect of the endophytic plant growth promoting Enterobacter ludwigii EB4B on tomato growth

Hellenic Plant Protection Journal ◽

10.2478/hppj-2020-0006 ◽

2020 ◽

Vol 13 (2) ◽

pp. 54-65 ◽

Cited By ~ 1

Author(s):

M.E.A. Bendaha ◽

H.A. Belaouni

Keyword(s):

Root Length ◽

Biocontrol Agent ◽

Growth Promotion ◽

Dry Weight ◽

Antagonistic Activity ◽

Rrna Gene ◽

Plant Growth Promoting ◽

Enterobacter Ludwigii ◽

Tomato Growth

SummaryThis study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.

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

mSphere ◽

10.1128/msphere.00484-20 ◽

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.

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

Revista de Biología Tropical ◽

10.15517/rbt.v67i4.34029 ◽

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.

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Influence of Plant growth promoting Rhizobacteria on growth and Biochemical Parameters of Corn (Zea mays l.) Var. Seedlings

THE JOURNAL OF MICROBIOLOGY AND MOLECULAR GENETICS ◽

10.52700/jmmg.v1i3.9 ◽

2020 ◽

Vol 1 (3) ◽

pp. 9-24

Author(s):

Huma Nawaz ◽

Saima Javed ◽

Muhammad Faisal

Keyword(s):

Bacillus Subtilis ◽

Plant Growth ◽

Biochemical Parameters ◽

Agricultural Practices ◽

Dry Weight ◽

Plant Growth Promoting Rhizobacteria ◽

Maximum Increase ◽

Pot Trials ◽

Plant Growth Promoting ◽

Bacillus Strains

Impact of inoculations of eight individual strains (CN2, CSH4, Cu35, CMS7, CSH23, CSH27, CF18, and Cu47, two combinations (Comb 4A and Comb 4B) of four Bacillus strains and mixture of all strains (Mix) was studied. Various growth and biochemical parameters of maize plant were determined in pot trials. Strain Bacillus subtilis CN2 showed 49% maximum increase in shoot length. The blend of entire strains was observed to have their lenghth increased about 21 %. Bacillus subtilis CN2 showed maximum increase 155%, in fresh biomass and 233 % increase in dry weight. Bacillus amyloliquefaciens (Cu47) and Comb 4A and showed maximum peroxidase content of 163 % and 94 % as compared to uninoculated control. Comb 4B was shown to have significant higher content of acidphosphatase (811 %). Increase in all other physical and biochemical parameters were noticed. Therefore, Bacillus strains exhibited characteristic increased potential of plant growth and can have great application in innovative agricultural practices.

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Plant growth-promoting properties of cultivable endophytic root nodule bacterial isolates from Acacia mangium Willd

Research in Plant Biology ◽

10.19071/ripb.2016.v6.3141 ◽

2016 ◽

Vol 6 ◽

Author(s):

Fatin Syafikah Ismail ◽

Masnindah Malahubban ◽

Mohammad Hailmi Sajili ◽

Zakry Fitri Ab. Aziz

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Root Nodules ◽

Acacia Mangium ◽

Dry Weight ◽

Winged Bean ◽

Bacterial Isolates ◽

Root And Shoot Length ◽

Plant Growth Promoting ◽

Growth Promoting

<strong>The present study was conducted to isolate and characterize endophytic bacteria isolated from root nodules of <em>Acacia mangium</em> Willd and subsequently tested for plant growth promotion. A total of five bacterial isolates were successfully isolated and subjected to morphological and biochemical examination. The present study found that all isolates had almost similar morphologically but differed in growth rate. All isolates were negative on N-free and IAA tests, though positive on P solubilisation test. The present study demonstrated that the inoculation with isolate FSI3 had significantly improved (p<0.05) root and shoot dry weight of winged bean seedlings as compared to uninoculated control. However, the inoculation did not significantly alter (p>0.05) root and shoot length of winged bean seedlings. The present study suggests that the stimulatory effect by isolate FSI3 may be associated with P-solubilizing ability. A further test on isolate FSI3 is considered essential in future to uncover the several other possible plant growth-promoting mechanisms. </strong>

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

New Zealand Plant Protection ◽

10.30843/nzpp.2015.68.5837 ◽

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

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Plant growth-promoting bacteria belonging to the genera Pseudomonas and Bacillus improve the growth of sorghum seedings in a low-nutrient soil

Botanical Sciences ◽

10.17129/botsci.2841 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Enriqueta Amora-Lazcano ◽

Héctor J. Quiroz-González ◽

Cristofer I. Osornio-Ortega ◽

Juan A. Cruz-Maya ◽

Janet Jan-Roblero

Keyword(s):

Plant Growth ◽

Growth Parameters ◽

Dry Weight ◽

Plant Growth Promoting Bacteria ◽

Phosphate Solubilizing Bacteria ◽

Bacterial Strains ◽

Shoot Dry Weight ◽

Soil Bioassay ◽

Plant Growth Promoting ◽

Growth Promoting

Background: Deficiency in sorghum growth in ecosystems of low-nutrient soils has been scarcely studied. This soil deficiency can be overcome by the addition of plant growth-promoting bacteria which increase sorghum growth. Questions and/or Hypotheses: indole acetic acid (IAA) producing and phosphate solubilizing bacteria can promote sorghum growth under nutritional stress. Studied species: Sorghum bicolor (L.) Moench. Study site and dates: Mexico City, 2018. Methods: Of the twelve bacterial strains utilized, three produce IAA (group BI), two strains produce IAA and siderophores (BIS group), four strains produce IAA and solubilize phosphate (BIP group), and three strains produce IAA, solubilize phosphate, and produce siderophores (BIPS group). Hydroponic bioassays and low-nutrient soil bioassay were used. Results: In hydroponic bioassays, for BI and BIS groups, five strains significantly increased the growth parameters with respect to the control, and for the BIP and BIPS groups, two strains promoted stem development and shoot dry weight. In a low-nutrient soil bioassay, Pseudomonas sp. BI-1 (from BI group) was the one that presented the highest percentages 32, 48, 140 and 79 % in stem diameter, height and dry weight of the shoot and dry weight of the root, respectively, followed by the P. mohnii BIPS-10 strain (from BIPS group) that exhibited similar results. Conclusions: IAA producing Pseudomonas strains improve the sorghum growth in a low-nutrient soil and suggest thatPseudomonas sp. BI-1 and P. mohnii BIPS-10 could be used as potential bioinoculants for sorghum.

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In-Vitro Plant Growth Promotion of Rhizobium Strains Isolated from Lentil Root Nodules under Abiotic Stresses

Agronomy ◽

10.3390/agronomy10071006 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1006

Author(s):

Badreddine Sijilmassi ◽

Abdelkarim Filali-Maltouf ◽

Sara Fahde ◽

Youness Ennahli ◽

Said Boughribil ◽

...

Keyword(s):

Abiotic Stress ◽

Salt Tolerance ◽

Plant Growth ◽

Growth Promotion ◽

Root Nodules ◽

Rhizobium Strains ◽

Drought And Salt Tolerance ◽

Significant Difference ◽

Plant Growth Promoting ◽

Growth Promoting

Plant growth-promoting rhizobia are known to improve crop performance by multiple mechanisms. However, the interaction between host plants and Rhizobium strains is highly influenced by growing conditions, e.g., heat, cold, drought, soil salinity, nutrient scarcity, etc. The present study was undertaken to assess the use of Rhizobium as plant growth promoters under abiotic stress conditions. Fifteen Rhizobium strains isolated from lentil root nodules were tested for phosphate solubilization activity (PSA) and phytohormones production under salt and drought conditions. The results showed that 15 Rhizobium strains were significant phosphate solubilizers, and indole acedic acid (IAA) and gibberellic acid (GA3) producers based on least significant difference (LSD) analysis (p ≤ 0.05). The highest rate of PSA was attributed to three strains namely, 1145N5, 1159N11, and 1159N32 with a range of 144.6 to 205.6 P2O5 (µg/mL). The highest IAA production was recorded in the strain 686N5 with 57.68 ± 4.25 µg/mL as compared to 50.8667 ± 1.41 µg/mL and 37.32 ± 12.59 µg/mL for Rhizobium tropici CIAT 899 and Azospirillum brasilense DSM-1690, respectively. Strain 318N2111 produced 329.24 ± 7.84 µg/mL of GA3 as against 259.84 ± 25.55 µg/mL for A. brasilense DSM-1690. R. tropici CIAT 899 showed tolerance to salt (5% NaCl) and drought (ψ = −2.6 MPa) stress, whereas strain 686N5 showed an extremely high level of salt-tolerance (5% NaCl) and moderate level of drought tolerance (ψ = −0.75 MPa). These results indicate different pathways for drought and salt tolerance mechanisms. The assessment of plant growth promoting (PGP) activities of Rhizobium showed differences between bacterial viability and bacterial PGP activity in terms of abiotic stress tolerance where bacterial PGP activity is interrupted before reaching the bacterial tolerance threshold. These results integrate a new concept of PGPR screening based on PGP activity under abiotic stress.

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Effect of Plant Growth Promoting Bacteria on the Growth of Wheat Seedlings Subjected to Phosphate Starvation

Agronomy ◽

10.3390/agronomy10070978 ◽

2020 ◽

Vol 10 (7) ◽

pp. 978

Author(s):

Mariagrazia P. Cataldi ◽

Sigrid Heuer ◽

Tim H. Mauchline ◽

Mark D. Wilkinson ◽

Emily Masters-Clark ◽

...

Keyword(s):

Plant Growth ◽

Dry Weight ◽

Root System Architecture ◽

Plant Growth Promoting Bacteria ◽

Wheat Seedlings ◽

Shoot Dry Weight ◽

P Content ◽

Bacillus Spp ◽

Plant Growth Promoting ◽

Molecular Indicators

Certain phosphorous solubilizing (PSB) and phosphorous mineralizing (PMB) bacteria may improve plant growth by improving nutrient availability. The aim of this work was to evaluate the effect of inoculation with two Bacillus spp. strains, 12A and 25A, on wheat seedlings growth. To this aim, a durum and a bread wheat genotype were grown under controlled conditions in a low P compost medium to evaluate: (i) the effect of the bacterial isolates on plant growth and root system architecture; (ii) the expression of two key genes indicative of the P-starvation response and phosphate (Pi) uptake, TaIPS1 and TaPHT1.6-B1. The results showed that 12A Bacillus sp. significantly increased root length, surface area and biomass. Furthermore, an enhanced shoot dry weight and P content were observed. This might be explained by the capacity of strain 12A to produce indole-3-acetic acid (IAA) in addition to P mineralizing and P solubilizing capability. No effect on plant growth was observed for 25A strain. The semi-quantitative gene expression analysis showed an overall lower expression of TaIPS1 in the inoculated plants and highest expression of TaPHT1.6-B1 in 12A inoculated plants. This suggests that Pi-responsive genes might be useful molecular indicators for the effectiveness of PSB and PMB.

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