The enhancement of plant growth by free-living bacteria

1995 ◽  
Vol 41 (2) ◽  
pp. 109-117 ◽  
Author(s):  
Bernard R. Glick
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Soil Bacteria ◽  
Genetic Manipulation ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Free Living ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Living Bacteria

The ways in which plant growth promoting rhizobacteria facilitate the growth of plants are considered and discussed. Both indirect and direct mechanisms of plant growth promotion are dealt with. The possibility of improving plant growth promoting rhizobacteria by specific genetic manipulation is critically examined.Key words: plant growth promoting rhizobacteria, PGPR, bacterial fertilizer, soil bacteria.

scholarly journals Characterization of Selected Plant Growth-Promoting Rhizobacteria and Their Non-Host Growth Promotion Effects

2021 ◽  
Author(s):  
Di Fan ◽  
Donald L. Smith
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Content Type ◽  
Host Growth ◽  
Plant Growth Promoting ◽  
Growth Promoting

There are pressing needs to reduce the use of agrochemicals, and PGPR are receiving increasing interest in plant growth promotion and disease protection. This study follows up our previous report that the four newly isolated rhizobacteria promote the growth of Arabidopsis thaliana .

scholarly journals A Framework for the Selection of Plant Growth-Promoting Rhizobacteria Based on Bacterial Competence Mechanisms

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Carol V. Amaya-Gómez ◽  
Mario Porcel ◽  
Leyanis Mesa-Garriga ◽  
Martha I. Gómez-Álvarez
Keyword(s):  
Hydrogen Peroxide ◽  
Plant Growth ◽  
Decision Analysis ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Screening Strategy ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Selection Of

ABSTRACT The use of plant growth-promoting rhizobacteria (PGPR) is increasingly meaningful for the development of more environmentally friendly agricultural practices. However, often the PGPR strains selected in the laboratory fail to confer the expected beneficial effects when evaluated in plant experiments. Insufficient rhizosphere colonization is pointed out as one of the causes. With the aim of minimizing this inconsistency, we propose that besides studying plant growth promotion traits (PGP), the screening strategy should include evaluation of the microbial phenotypes required for colonization and persistence. As a model, we carried out this strategy in three Rhizobium sp. strains that showed phosphorus solubilization ability and production of siderophores. All strains displayed colonization phenotypes like surface spreading, resistance to hydrogen peroxide, and formed biofilms. Regarding their ability to persist, biofilm formation was observed to be influenced by pH and the phosphorus nutrient provided in the growth media. Differences in the competence of the strains to use several carbon substrates were also detected. As part of our framework, we compared the phenotypic characteristics of the strains in a quantitative manner. The data analysis was integrated using a multicriteria decision analysis (MCDA). All our results were scored, weighted, and grouped as relevant for PGP, colonization, or persistence. MCDA demonstrated that, when the phenotypes related to PGP and colonization are weighted over those for persistence, strain B02 performs better than the other two Rhizobium sp. strains. The use of our framework could assist the selection of more competent strains to be tested in greenhouse and field trials. IMPORTANCE Numerous plant growth-promoting rhizobacteria (PGPR) have been inoculated into the soil with the aim of improving the supply of nutrients to crop plants and decreasing the requirement of chemical fertilizers. However, sometimes these microbes fail to competitively colonize the plant roots and rhizosphere. Hence, the plant growth promotion effect is not observed. Here, we describe a new screening strategy aiming at the selection of more competent PGPR. We evaluated bacterial phenotypes related to plant growth promotion, colonization, and persistence. Our results demonstrated that despite the fact that our Rhizobium sp. strains successfully solubilized phosphorus and produced siderophores, their abilities to spread over surfaces, resist hydrogen peroxide, and form biofilms varied. Additionally, a multicriteria decision analysis was used to analyze the data that originated from bacterial physiological characterizations. This analysis allowed us to innovatively evaluate each strain as a whole and compare the performances of the strains under hypothetical scenarios of bacterial-trait requirements.

scholarly journals Mixtures of Plant-Growth-Promoting Rhizobacteria Enhance Biological Control of Multiple Plant Diseases and Plant-Growth Promotion in the Presence of Pathogens

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Ke Liu ◽  
John A. McInroy ◽  
Chia-Hui Hu ◽  
Joseph W. Kloepper
Keyword(s):  
Biological Control ◽  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Pythium Ultimum ◽  
Plant Diseases ◽  
Disease Suppression ◽  
Plant Growth Promoting ◽  
Growth Promoting

Several studies have shown that mixtures of plant-growth-promoting rhizobacteria (PGPR) could enhance biological control activity for multiple plant diseases through the mechanisms of induced systemic resistance or antagonism. Prior experiments showed that four individual PGPR strains—AP69 (Bacillus altitudinis), AP197 (B. velezensis), AP199 (B. velezensis), and AP298 (B. velezensis)—had broad-spectrum biocontrol activity via antagonism in growth chambers against two foliar bacterial pathogens (Xanthomonas axonopodis pv. vesicatoria and Pseudomonas syringae pv. tomato) and one of two tested soilborne fungal pathogens (Rhizoctonia solani and Pythium ultimum). Based on these findings, the overall hypothesis of this study was that a mixture of two individual PGPR strains would exhibit better overall biocontrol and plant-growth promotion than the individual PGPR strains. Two separate greenhouse experiments were conducted. In each experiment, two individual PGPR strains and their mixtures were tested for biological control of three different diseases and for plant-growth promotion in the presence of the pathogens. The results demonstrated that the two individual PGPR strains and their mixtures exhibited both biological control of multiple plant diseases and plant-growth promotion. Overall, the levels of disease suppression and growth promotion were greater with mixtures than with individual PGPR strains.

scholarly journals Effects of two rhizobacteria inoculants on maize growth performance at different concentrations of glyphosate

2020 ◽  
Vol 37 (1) ◽  
pp. 21-37
Author(s):  
P.O. Akintokun ◽  
E. Ezaka ◽  
A.K. Akintokun ◽  
O.A. Oyedele
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Plant Growth Promoting Rhizobacteria ◽  
Field Studies ◽  
Significant Difference ◽  
Plant Growth Promoting ◽  
Number Of Leaves ◽  
Growth Promoting ◽  
Screen House

The use of Rhizobacteria as biofertilizer is on the increase due to the ability of some of the bacteria to solubilize some insoluble essential nutrients in the soil and produce phytohormones necessary for plant growth. The effectiveness of two plant growth promoting rhizobacteria (Bacillus cereus and Pseudomonas aeruginosa) in plant growth promotion at different concentrations of glyphosate were evaluated. Some agronomic parameters such as plant height, size of girth, number of leaves on the screen house and field were measured and recorded. The results of the effects of P. aeruginosa on the height of maize at different concentrations showed that the plants inoculated with the isolates and planted on the soil without glyphosate (control) recorded the highest height on the 2nd (34.9 cm), 4th (52.45 cm), 6th (61.17 cm) and 8th (66.25 cm) weeks after planting, when compared to those planted on the soil spiked with different concentrations of glyphosate. The effects of the isolates on the size of girth of maize on the soil spiked with different concentrations of glyphosate showed the highest girth size on the soil inoculated with P. aeruginosa eight weeks after planting (8 WAP) with a girth size of 2.0cm and least at 14.4 mg/ml of glyphosate with a girth size of 1.2 cm at 8 weeks after planting. Similar trend was observed on the soil inoculated with B. cereus (without glyphosate) with the highest girth in the 2nd and 4th WAP (1.02 and 1.42 cm, respectively). The results of our field studies showed no significant difference (P≤0.05) in the height and number of leaves of the maize at different treatments and time (weeks after planting). Similar trend was observed i n the yield of maize. This study has shown that these isolates can be useful as biofertilizers especially in the absence or at low concentration of glyphosate. Keywords: Rhizobacteria, maize, Inoculants, Plant-growth-promotion.

scholarly journals The Root Microbiome of Salicornia ramosissima as a Seedbank for Plant-Growth Promoting Halotolerant Bacteria

2021 ◽  
Vol 11 (5) ◽  
pp. 2233
Author(s):  
Maria J. Ferreira ◽  
Angela Cunha ◽  
Sandro Figueiredo ◽  
Pedro Faustino ◽  
Carla Patinha ◽  
...  
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Cultivated Plants ◽  
Plant Growth Promoting Bacteria ◽  
Crop Cultivation ◽  
Halotolerant Bacteria ◽  
Salicornia Ramosissima ◽  
Plant Growth Promoting ◽  
Growth Promoting

Root−associated microbial communities play important roles in the process of adaptation of plant hosts to environment stressors, and in this perspective, the microbiome of halophytes represents a valuable model for understanding the contribution of microorganisms to plant tolerance to salt. Although considered as the most promising halophyte candidate to crop cultivation, Salicornia ramosissima is one of the least-studied species in terms of microbiome composition and the effect of sediment properties on the diversity of plant-growth promoting bacteria associated with the roots. In this work, we aimed at isolating and characterizing halotolerant bacteria associated with the rhizosphere and root tissues of S. ramosissima, envisaging their application in saline agriculture. Endophytic and rhizosphere bacteria were isolated from wild and crop cultivated plants, growing in different estuarine conditions. Isolates were identified based on 16S rRNA sequences and screened for plant-growth promotion traits. The subsets of isolates from different sampling sites were very different in terms of composition but consistent in terms of the plant-growth promoting traits represented. Bacillus was the most represented genus and expressed the wider range of extracellular enzymatic activities. Halotolerant strains of Salinicola, Pseudomonas, Oceanobacillus, Halomonas, Providencia, Bacillus, Psychrobacter and Brevibacterium also exhibited several plant-growth promotion traits (e.g., 3-indole acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophores, phosphate solubilization). Considering the taxonomic diversity and the plant-growth promotion potential of the isolates, the collection represents a valuable resource that can be used to optimize the crop cultivation of Salicornia under different environmental conditions and for the attenuation of salt stress in non-halophytes, considering the global threat of arable soil salinization.

Isolation, identification and characterization of native plant growth promoting bacteria and their plant growth promotion in Zea mays

2021 ◽  
Vol 16 (8) ◽  
pp. 75-80
Author(s):  
Pitchaiah Pelapudi ◽  
Sasikala Ch ◽  
Swarnabala Ganti
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Root Length ◽  
Growth Promotion ◽  
Shoot Length ◽  
Root Weight ◽  
Plant Growth Promoting Bacteria ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Shoot Weight

In the present rapid growing world, need for a sustainable agricultural practice which helps in meeting the adequate food demand is much needed. In this context, plant growth promoting bacteria were brought into the spot light by the researchers. Though the plant growth promoting bacteria have several beneficial applications, due to some of the disadvantages in the field conditions, they lagged behind. In the current research work, native PGPR were isolated from the rhizosphere soil samples of maize with an aim to isolate the nitrogen fixing, phosphate solubilising and potash solubilising bacteria. Out of the several isolates, potent PGPR isolates viz., Paenibacillus durus PCPB067, Bacillus megaterium PCBMG041 and Paenibacillus glucanolyticus PCPG051 were isolated and identified by using the 16 S rRNA gene sequencing studies. Genomic DNA sequences obtained were deposited in the NCBI Genbank and accession numbers were assigned as MW793452, MW793456 and MW843633. In order to check the efficacy of the PGPR isolates, pot trials were conducted by taking maize as the host plant. Several parameters viz. shoot length, shoot weight, root length, root weight and weight of the seeds were tested in which PGP treatment showed good results (shoot length - 187±3.5 cm, shoot weight - 31±4 g, root length - 32±3.6 cm, root weight - 17±2 g, yield- 103.3±6.1 g) when compared to the chemical fertilizer treatment (shoot length - 177±3.5 cm, shoot weight - 25±3.6 g, root length - 24±3.5 cm, root weight - 14.6±1.52 g, yield- 85.6±7.6 g). Based on the results, it can be stated that these native PGPR isolates can be effectively used in the plant growth promotion of maize.

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