Functional Investigation of Plant Growth Promoting Rhizobacterial Communities in Sugarcane

Plant microbiota are of great importance for host nutrition and health. As a C4 plant species with a high carbon fixation capacity, sugarcane also associates with beneficial microbes, though mechanisms underlying sugarcane root-associated community development remain unclear. Here, we identify microbes that are specifically enriched around sugarcane roots and report results of functional testing of potentially beneficial microbes propagating with sugarcane plants. First, we analyzed recruitment of microbes through analysis of 16S rDNA enrichment in greenhouse cultured sugarcane seedlings growing in field soil. Then, plant-associated microbes were isolated and assayed for beneficial activity, first in greenhouse experiments, followed by field trials for selected microbial strains. The promising beneficial microbe SRB-109, which quickly colonized both roots and shoots of sugarcane plants, significantly promoted sugarcane growth in field trials, nitrogen and potassium acquisition increasing by 35.68 and 28.35%, respectively. Taken together, this report demonstrates successful identification and utilization of beneficial plant-associated microbes in sugarcane production. Further development might facilitate incorporation of such growth-promoting microbial applications in large-scale sugarcane production, which may not only increase yields but also reduce fertilizer costs and runoff.

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Film coating of seeds with Bacillus cereus RS87 spores for early plant growth enhancement

Canadian Journal of Microbiology ◽

10.1139/w08-079 ◽

2008 ◽

Vol 54 (10) ◽

pp. 861-867 ◽

Cited By ~ 9

Author(s):

Kanchalee Jetiyanon ◽

Sakchai Wittaya-Areekul ◽

Pinyupa Plianbangchang

Keyword(s):

Plant Growth ◽

Bacillus Cereus ◽

Plant Height ◽

Root Length ◽

Film Coating ◽

Field Trials ◽

Growth Enhancement ◽

Vegetative Cells ◽

Plant Growth Promoting ◽

Growth Promoting

The plant growth-promoting rhizobacterium Bacillus cereus RS87 was previously reported to promote plant growth in various crops in both greenhouse and field trials. To apply as a plant growth promoting agent with practical use, it is essential to ease the burden of routine preparation of a fresh suspension of strain RS87 in laboratory. The objectives of this study were to investigate the feasibility of film-coating seeds with B. cereus RS87 spores for early plant growth enhancement and to reveal the indoleacetic acid (IAA) production released from strain RS87. The experiment consisted of the following 5 treatments: nontreated seeds, water-soaked seeds, film-coated seeds, seeds soaked with vegetative cells of strain RS87, and film-coated seeds with strain RS87 spores. Three experiments were conducted separately to assess seed emergence, root length, and plant height. Results showed that both vegetative cells and spores of strain RS87 significantly promoted (P ≤ 0.05) seed emergence, root length and plant height over the control treatments. The strain RS87 also produced IAA. In conclusion, the film coating of seeds with spores of B. cereus RS87 demonstrated early plant growth enhancement as well as seeds using their vegetative cells. IAA released from strain RS87 would be one of the mechanisms for plant growth enhancement.

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Plant growth-promoting microbes — an industry view

Emerging Topics in Life Sciences ◽

10.1042/etls20200313 ◽

2021 ◽

Author(s):

Natalie W. Breakfield ◽

Dayna Collett ◽

Michael E. Frodyma

Keyword(s):

Plant Growth ◽

Large Scale ◽

Selection Process ◽

Cost Effective ◽

Field Testing ◽

Product Concept ◽

Large Scale Field ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Plant Growth Promoting Microbes

Plant growth-promoting microbes can affect the plant microbiome, improving different properties of the plant such as yield and health. Many companies are commercializing these microbes as products called biologicals. Defining the product concept is one of the first and most important steps in making a biological product. Companies can use phenotyping and genotyping approaches to identify the microbe to make into a live bacterial product. Screening usually begins in the laboratory and often moves from high-throughput methods to more time and resource-intensive methods culminating in large scale field testing. Once the microbe is chosen, the fermentation process grows the bacteria to the necessary amounts, while the formulation process ensures a stable product in the desired form such as a liquid or powder. The products must show yield increases in the field over several seasons and conditions, but also must be easy to use and cost-effective to be adopted by farmers and other customers. Tying all these data together from the selection process to test results gives a customer a ‘reason to believe’ for the marketing and launch of a successful product.

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Mycorrhizal-Bacterial Amelioration of Plant Abiotic and Biotic Stress

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.672881 ◽

2021 ◽

Vol 5 ◽

Author(s):

Gustavo Santoyo ◽

Elisa Gamalero ◽

Bernard R. Glick

Keyword(s):

Plant Growth ◽

Mycorrhizal Fungi ◽

Synergistic Effects ◽

Plant Stress ◽

Plant Growth Promoting Bacteria ◽

Abiotic And Biotic Stress ◽

Different Types ◽

Plant Growth Promoting ◽

Plant Microbiota ◽

Growth Promoting

Soil microbiota plays an important role in the sustainable production of the different types of agrosystems. Among the members of the plant microbiota, mycorrhizal fungi (MF) and plant growth-promoting bacteria (PGPB) interact in rhizospheric environments leading to additive and/or synergistic effects on plant growth and heath. In this manuscript, the main mechanisms used by MF and PGPB to facilitate plant growth are reviewed, including the improvement of nutrient uptake, and the reduction of ethylene levels or biocontrol of potential pathogens, under both normal and stressful conditions due to abiotic or biotic factors. Finally, it is necessary to expand both research and field use of bioinoculants based on these components and take advantage of their beneficial interactions with plants to alleviate plant stress and improve plant growth and production to satisfy the demand for food for an ever-increasing human population.

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A genome-annotated bacterial collection of the barley rhizosphere microbiota

10.1101/2021.03.10.434690 ◽

2021 ◽

Author(s):

Senga Robertson-Albertyn ◽

Federico Concas ◽

Lynn H Brown ◽

Jamie N Orr ◽

James C Abbott ◽

...

Keyword(s):

Plant Growth ◽

Genomic Analysis ◽

Comparative Genomic Analysis ◽

Comparative Genomic ◽

Strain Specificity ◽

Bacterial Microbiota ◽

A Genome ◽

Plant Growth Promoting ◽

Plant Microbiota ◽

Growth Promoting

ABSTRACTWe generated a bacterial collection from the rhizosphere of cultivated barley (Hordeum vulgare L. ssp. vulgare) to assess taxonomic distribution of culturable members of the barley microbiota and their plant growth-promoting potential. From this we retrieved strains belonging to the dominant phyla of the plant microbiota— Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria—and gathered evidence they code for functional genes implicated in nitrogen fixation, hydrogen cyanide channels and phosphate solubilisation. Here we present an initial comparative genomic analysis of the collection revealing that plant growth-promoting potential of the culturable barley bacterial microbiota appears to have a relatively broad phylogenetic base while retaining some strain-specificity.

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Fire in pine grown regions of Himalayas depletes cultivable plant growth promoting beneficial microbes in the soil

Applied Soil Ecology ◽

10.1016/j.apsoil.2019.03.020 ◽

2019 ◽

Vol 139 ◽

pp. 117-124 ◽

Cited By ~ 3

Author(s):

Divya Mittal ◽

Rakesh Shukla ◽

Sudhir Verma ◽

Anand Sagar ◽

Kartar S. Verma ◽

...

Keyword(s):

Plant Growth ◽

Beneficial Microbes ◽

Plant Growth Promoting ◽

Growth Promoting

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Inoculation of native symbiotic effective Sinorhizobium spp. enhanced soybean [Glycine max (L.) Merr.] grain yield in Ethiopia

ENVIRONMENTAL SYSTEMS RESEARCH ◽

10.1186/s40068-020-00205-1 ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Diriba Temesgen ◽

Fassil Assefa

Keyword(s):

Glycine Max ◽

Plant Growth ◽

Grain Yield ◽

Phenotypic Variability ◽

Computer Software ◽

Field Trials ◽

Soybean Plant ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

Abstract Background Soybean [Glycine max (L) Merr.] is an annual leguminous crop serving as a source of food and feed, green manure, biodiesel and fiber. It is nodulated by diverse slow growing and fast growing rhizobia belonging to the genus Bradyrhizobium and Sinorhizobium, respectively. In Ethiopia, it has been cultivated since 1950s with lower grain yield history. Yield improvement efforts have been more concentrated on agronomic studies, inoculation of exotic Bradyrhizobium japonicum including TAL379 and/or fertilizer application. The results have usually been unsatisfactory and inconsistent. This study was initiated to identify promising indigenous soybean rhizobial inoculant that can enhance yield of the crop in the country. Methods Native soybean rhizobia, designated GMR for Glycine max rhizobia, were trapped using soybean (cv. Ethio-Yugoslavia) from soils collected across agro-ecologies of Ethiopia. They were screened for in vitro tolerance against physico-chemical stresses, plant growth promoting (PGP) traits and symbiotic performances at greenhouse and field levels. A reference B. japonicum (TAL379) was included in all experiments. A soybean plant growth promoting Achromobacter sp. was also included in field trials for co-inoculation. Quantitative data were assessed by analysis of variance (ANOVA) employing SAS computer software package version 9.3. Mean separations were undertaken using Duncan’s Multiple Range Test at p ≤ 0.05. Phenotypic variability of the test bacteria was undertaken using PAST4.03 Computer Software. Result GMR that produced acid and grew faster with larger colonies were identified as Sinorhizobium spp. and those which produced alkali and grew slowly with smaller colonies were identified as Bradyrhizobium spp. though further genetic analysis should be performed for verification and identification of their genus and species, respectively. Two Sinorhizobium spp. (GMR120C and GMR125B) profoundly nodulated different soybean cultivars under greenhouse conditions and significantly improved grain yield (p ≤ 0.05; maximum 3.98 tons ha−1) compared to 2.41, 2.82 and 2.69 recorded as maximum grain yield (tons ha−1) for TAL379 inoculation, positive control and negative control, respectively in field trials. Higher yield was recorded when GMR125B was co-inoculated with Achromobacter sp., but when GMR120C was inoculated singly. These GMR also showed efficient utilization of numerous substrates, some PGP traits and potential adaptation to various ecological stresses. Conclusion The two Sinorhizobium spp. (GMR120C and GMR125B) are promising soybean inoculants that can be used to enhance the productivity of the crop in the country.

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Plant Growth-Promoting Bacteria as an Emerging Tool to Manage Bacterial Rice Pathogens

Microorganisms ◽

10.3390/microorganisms9040682 ◽

2021 ◽

Vol 9 (4) ◽

pp. 682

Author(s):

Mohamad Syazwan Ngalimat ◽

Erneeza Mohd Hata ◽

Dzarifah Zulperi ◽

Siti Izera Ismail ◽

Mohd Razi Ismail ◽

...

Keyword(s):

Plant Growth ◽

Large Scale ◽

Plant Growth Promoting Bacteria ◽

Promising Alternative ◽

Rice Plants ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Rice Pathogens ◽

Grain Losses

As a major food crop, rice (Oryza sativa) is produced and consumed by nearly 90% of the population in Asia with less than 9% produced outside Asia. Hence, reports on large scale grain losses were alarming and resulted in a heightened awareness on the importance of rice plants’ health and increased interest against phytopathogens in rice. To serve this interest, this review will provide a summary on bacterial rice pathogens, which can potentially be controlled by plant growth-promoting bacteria (PGPB). Additionally, this review highlights PGPB-mediated functional traits, including biocontrol of bacterial rice pathogens and enhancement of rice plant’s growth. Currently, a plethora of recent studies address the use of PGPB to combat bacterial rice pathogens in an attempt to replace existing methods of chemical fertilizers and pesticides that often lead to environmental pollutions. As a tool to combat bacterial rice pathogens, PGPB presented itself as a promising alternative in improving rice plants’ health and simultaneously controlling bacterial rice pathogens in vitro and in the field/greenhouse studies. PGPB, such as Bacillus, Pseudomonas, Enterobacter, Streptomyces, are now very well-known. Applications of PGPB as bioformulations are found to be effective in improving rice productivity and provide an eco-friendly alternative to agroecosystems.

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Plant Microbiota Beyond Farming Practices: A Review

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.624203 ◽

2021 ◽

Vol 5 ◽

Author(s):

Mathieu Delitte ◽

Simon Caulier ◽

Claude Bragard ◽

Nicolas Desoignies

Keyword(s):

Plant Growth ◽

Microbial Communities ◽

Agricultural Practices ◽

Farming Practices ◽

Smart Farming ◽

Plant Growth Promoting ◽

Plant Microbiota ◽

Growth Promoting ◽

Chemical Inputs ◽

Beneficial Traits

Plants have always grown and evolved surrounded by numerous microorganisms that inhabit their environment, later termed microbiota. To enhance food production, humankind has relied on various farming practices such as irrigation, tilling, fertilization, and pest and disease management. Over the past few years, studies have highlighted the impacts of such practices, not only in terms of plant health or yields but also on the microbial communities associated with plants, which have been investigated through microbiome studies. Because some microorganisms exert beneficial traits that improve plant growth and health, understanding how to modulate microbial communities will help in developing smart farming and favor plant growth-promoting (PGP) microorganisms. With tremendous cost cuts in NGS technologies, metagenomic approaches are now affordable and have been widely used to investigate crop-associated microbiomes. Being able to engineer microbial communities in ways that benefit crop health and growth will help decrease the number of chemical inputs required. Against this background, this review explores the impacts of agricultural practices on soil- and plant-associated microbiomes, focusing on plant growth-promoting microorganisms from a metagenomic perspective.

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Mixtures of Plant Growth-Promoting Rhizobacteria Enhance Biological Control of Multiple Cucumber Pathogens

Phytopathology ◽

10.1094/phyto.1998.88.11.1158 ◽

1998 ◽

Vol 88 (11) ◽

pp. 1158-1164 ◽

Cited By ~ 341

Author(s):

Georg S. Raupach ◽

Joseph W. Kloepper

Keyword(s):

Biological Control ◽

Plant Growth ◽

Leaf Spot ◽

Plant Growth Promoting Rhizobacteria ◽

Field Trials ◽

Disease Suppression ◽

Angular Leaf Spot ◽

Systemic Resistance ◽

Plant Growth Promoting ◽

Growth Promoting

Plant growth-promoting rhizobacteria (PGPR) strains INR7 (Bacillus pumilus), GB03 (Bacillus subtilis), and ME1 (Curtobacterium flaccumfaciens) were tested singly and in combinations for biological control against multiple cucumber pathogens. Investigations under greenhouse conditions were conducted with three cucumber pathogens—Colletotrichum orbiculare (causing anthracnose), Pseudomonas syringae pv. lachrymans (causing angular leaf spot), and Erwinia tracheiphila(causing cucurbit wilt disease)—inoculated singly and in all possible combinations. There was a general trend across all experiments toward greater suppression and enhanced consistency against multiple cucumber pathogens using strain mixtures. The same three PGPR strains were evaluated as seed treatments in two field trials over two seasons, and two strains, IN26 (Burkholderia gladioli) and INR7 also were tested as foliar sprays in one of the trials. In the field trials, the efficacy of induced systemic resistance activity was determined against introduced cucumber pathogens naturally spread within plots through placement of infected plants into the field to provide the pathogen inoculum. PGPR-mediated disease suppression was observed against angular leaf spot in 1996 and against a mixed infection of angular leaf spot and anthracnose in 1997. The three-way mixture of PGPR strains (INR7 plus ME1 plus GB03) as a seed treatment showed intensive plant growth promotion and disease reduction to a level statistically equivalent to the synthetic elicitor Actigard applied as a spray.

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Towards Sustainable Bioinoculants: A Fermentation Strategy for High Cell Density Cultivation of Paraburkholderia sp. SOS3, a Plant Growth-Promoting Bacterium Isolated in Queensland, Australia

Fermentation ◽

10.3390/fermentation7020058 ◽

2021 ◽

Vol 7 (2) ◽

pp. 58

Author(s):

Ian Petersen ◽

Chanyarat Paungfoo-Lonhienne ◽

Esteban Marcellin ◽

Lars Keld Nielsen ◽

Axayacatl Gonzalez

Keyword(s):

Plant Growth ◽

Cell Density ◽

Large Scale ◽

Biomass Yield ◽

High Cell Density ◽

High Cell ◽

Fed Batch ◽

Batch Cultures ◽

Plant Growth Promoting ◽

Growth Promoting

Paraburkholderia sp. SOS3 is a plant growth-promoting bacterium (PGPB) that displays pleiotropic effects and has the potential to be applied at a large scale across several agronomically important crops. The use of SOS3 is a suitable option to reduce the use of chemical fertilisers. While the benefits of SOS3 have been demonstrated in vitro, its potential applications at large scale are limited due to low biomass yield in current batch culture systems. Here, we developed a strategy for high-cell density cultivation of SOS3 in instrumented bioreactors, moving from low-biomass yield in a complex medium to high-biomass yield in a semi-defined medium. We achieved a 40-fold increase in biomass production, achieving cell densities of up to 11 g/L (OD600 = 40). This result was achieved when SOS3 was cultivated using a fed-batch strategy. Biomass productivity, initially 0.02 g/L/h in batch cultures, was improved 12-fold, reaching 0.24 g/L/h during fed-batch cultures. The biomass yield was also improved 10-fold from 0.07 to 0.71 gbiomass/gsolids. Analysis of the fermentation profile of SOS3 indicated minimal production of by-products and accumulation of polyhydroxybutyrate (PHB) during the exponential growth phase associated with nitrogen limitation in the medium. By implementing proteomics analysis in fed-batch cultures, we identified the expression of four metabolic pathways associated with growth-promoting effects, which may be used as a qualitative parameter to guarantee the efficacy of SOS3 when used as a bioinoculant. Ultimately, we confirmed that the high-cell density cultures maintained their plant growth-promoting capacity when tested in sorghum and maize under glasshouse conditions.

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