Proposal for the division of plant growth-promoting rhizobacteria into two classifications: biocontrol-PGPB (plant growth-promoting bacteria) and PGPB

1998 ◽  
Vol 30 (8-9) ◽  
pp. 1225-1228 ◽  
Author(s):  
Yoav Bashan ◽  
Gina Holguin
2011 ◽  
Vol 12 (2) ◽  
pp. 159 ◽  
Author(s):  
Mauricio Camelo R. ◽  
Sulma Paola Vera M. ◽  
Ruth Rebeca Bonilla B.

<p>La dinámica poblacional de la especie humana ha llevado a que la explotación de los recursos naturales, en búsqueda de suplir las necesidades alimenticias de los miles de millones de personas que habitan el planeta. Esta necesidad ha llevado a la utilización de materiales de alta eficiencia en la agricultura, variedades vegetales resistentes a plagas y enfermedades con ciclos de producción más cortos, agroquímicos que surten las necesidades nutricionales y provean protección frente factores bióticos adversos (plagas y enfermedades). Sin embargo, estas estrategias utilizadas en la agricultura moderna han generado impactos ambientales negativos que aún no comprendemos. La contaminación de aguas freáticas, eutrofización, aumento de gases de invernadero y acumulación de sustancias toxicas en la cadena trófica, son algunos de los graves problemas que se presentan por el uso indiscriminado de agroquímicos. Como alternativa a la utilización de estas sustancias, se ha propuesto el uso de bacterias rizosféricas que tienen reconocida acción sobre el crecimiento y desarrollo vegetal (PGPR, por sus siglas en ingles). Estas bacterias son capaces de estimular el desarrollo de las plantas de manera directa e indirecta y poseen una serie de mecanismos complejos que interactúan entre sí para establecer relaciones benéficas, especialmente con las raíces de las plantas objetivo. El estudio y entendimiento de las PGPR han sido temas de gran importancia en muchas investigaciones a nivel mundial, por esta razón esta revisión tiene por objetivo hacer una revisión parcial para dar a conocer los mecanismos que poseen las rizobacterias promotoras del crecimiento vegetal en el desarrollo de las plantas, así como el papel que desempeñan en el ciclaje de nutrientes.</p><p> </p><p><strong>Mechanisms of action of plant growth promoting rhizobacteria.</strong></p><p>The population dynamics of the human race has led to the exploitation of natural resources in search of a way to meet the nutritional needs of the billions of people inhabiting the planet. This need has led to the use of high-efficiency materials in agriculture, plant varieties with shorter production cycles that are also resistant to pests and diseases, and chemicals that provide protection against biotic factors (pests and disease), additionally the nutrients required to grow plants. However, the strategies used in modern agriculture have led to negative environmental impacts that we have yet to fully understand. Groundwater contamination, eutrophication, increased greenhouse gases, and the accumulation of toxic substances in the food chain are some of the serious problems that have arisen worldwide due to the indiscriminate use of agrochemicals. As an alternative to the use of these substances, the use of rhizopheric bacteria has been proposed owing to its known action as plant growth- promoting bacteria (PGPB). These bacteria are able to stimulate plant growth directly and indirectly and have several complex mechanisms that interact with each other to establish beneficial relationships, especially with the roots of target plants. The study and understanding of PGPR have been the subjects of great importance in many studies at a global level. This review, therefore, aims to better understand the mechanisms of plant growth-promoting rhizobacteria on plant development and their role in nutrient cycling.</p>


Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2065
Author(s):  
Hammad Anwar ◽  
Xiukang Wang ◽  
Azhar Hussain ◽  
Muhammad Rafay ◽  
Maqshoof Ahmad ◽  
...  

Plant growth-promoting rhizobacteria with multiple growth-promoting traits play a significant role in soil to improve soil health, crop growth and yield. Recent research studies have focused on the integration of organic amendments with plant growth-promoting rhizobacteria (PGPR) to enhance soil fertility and reduce the hazardous effects of chemical fertilizers. This study aims to evaluate the integrated application of biochar, compost, fruit and vegetable waste, and Bacillus subtilis (SMBL 1) to soil in sole application and in combined form. The study comprises eight treatments—four treatments without inoculation and four treatments with SMBL 1 inoculation in a completely randomized design (CRD), under factorial settings with four replications. The results indicate that the integrated treatments significantly improved okra growth and yield compared with sole applications. The integration of SMBL 1 with biochar showed significant improvements in plant height, root length, leaf chlorophyll a and b, leaf relative water content, fruit weight, diameter and length by 29, 29, 50, 53.3, 4.3, 44.7 and 40.4%, respectively, compared with control. Similarly, fruit N, P and K contents were improved by 33, 52.7 and 25.6% and Fe and Zn in shoot were 37.1 and 35.6%, respectively, compared with control. The results of this study reveal that the integration of SMBL 1 with organic amendments is an effective approach to the sustainable production of okra.


2019 ◽  
Vol 13 (1) ◽  
pp. 215-222 ◽  
Author(s):  
Yuliya Kolomiiets ◽  
Ivan Grygoryuk ◽  
Artur Likhanov ◽  
Lyudmila Butsenko ◽  
Yaroslav Blume

Background: By inducing the production of inhibitory allelochemicals and mechanisms of systemic resistance plant growth promoting bacteria (PGPB) help plants to cope with stresses. Materials and Methods: In this study cell suspensions of Bacillus subtilis, Pseudomonas fluorescens or Azotobacter chroococcum were used to test the efficacy of these PGPB in inducing resistance in tomato (Lycopersicon esculentum Mill) against Clavibacter michiganensis subsp michiganensis, a bacteria known to cause canker disease. To test this hypothesis, seedlings of Chaika variety, characterized by short growing, early-ripening, high productivity and resistance against fusarium and the C. michiganensis strain ІZ-38 isolated in Kyiv were employed. Results and Conclusion: The use of cell suspensions of the PGPB B. subtilis, A. chroococcum or P. fluorescens induced an increment in the resistance of tomato plants against the causative agent of bacterial canker (C. michiganensis subsp. michiganensis) by 42–50%. PGPB in fact promoted in C. michiganensis infected tomato plants: i) the accumulation of chlorophyll a and b and carotenoids; ii) the thickening of the upper and lower epidermis of leaves; iii) the deposition of biopolymers with protective properties in epidermal cells; iv) the activity of the peroxidase enzyme and v) the net productivity of photosynthesis.


2021 ◽  
Vol 6 (2) ◽  
pp. 255-263
Author(s):  
Indah Juwita Sari ◽  
Indria Wahyuni ◽  
Rida Oktorida Khastini ◽  
Ewi Awaliyati ◽  
Andriana Susilowati ◽  
...  

Plant Growth Promoting Bacteria Rhizobacteria (PGPR) is one of the potential bacteria to enhance of Capsicum annuum through inhabitation the growth of pathogenic fungi. This study aimed to characterize PGPR in chili plants (Capsicum annuum). PGPR was isolated from the soil habitat of the red chili plant in Cilegon, Indonesia. Screening was then carried out with the dual culture method on Petri dishes and tested through in vivo method on the red chili plant. The selected bacteria were characterized morphologically, biochemically, and physiologically. The results revealed that there were 14 single isolates of bacteria from the roots of the red chili plants. The five single bacterial isolates, namely Azostobacter, Azospirillum, Pseudomonas, Serratia, and Beijerinckia have good potential as PGPR based on multiple culture screening by producing clear zones and positively effect the growth of chili plants.


Author(s):  
Ibrahim El-Akhdar ◽  
Tamer Elsakhawy ◽  
Hanaa A. Abo-Koura

The plant growth-promoting rhizobacteria (PGPR) application could reduce the use of synthetic fertilizers and increase the sustainability of crop production. Halophilic bacteria that have PGPR characteristics can be used in different environmental stresses. Two different strains isolated, purified, characterized as a PGPRs and phylogenetic identification using 16sRNA which was revealed to be closest matched at 99% with Bacillus halotolerans and Lelliottia amnigena. The isolates possessed plant growth promoting properties as exopolysaccharides (EPS) and indole acetic acid (IAA) production, Bacillus halotolerans had the ability to fix elemental nitrogen and the two strains have the ability to P-solubilization. Furthermore, the strains were evaluated in alleviation of different levels of salt stress on wheat plant at two experiments (Pots and a Field). Strains under study conditions significantly increased the plant height, straw dry weight (DW g plant-1), spike number, 1000 grain DW recorded 31.550 g with Lelliottia amnigena MSR-M49 compared to un-inoculated and other strain in field,  grain yield recorded 2.77 (ton fed-1) with Lelliottia amnigena  as well as N% and protein content in grains recorded 1.213% and 6.916 respectively with  inoculation with Lelliottia amnigena,  also, spikes length, inoculated wheat show reduction in both proline accumulation in shoots and roots especially with Lelliottia amnigena recorded 2.79 (mg g-1DW), inoculation significantly increased K+ in root-shoot, K+/Na+ in root-shoot and reduced Na+ in root-shoot compared with control. This confirmed that this consortium could provide growers with a sustainable approach to reduce salt effect on wheat production.


2011 ◽  
Vol 57 (11) ◽  
pp. 914-922 ◽  
Author(s):  
Ganisan Krishnen ◽  
Mihály L. Kecskés ◽  
Michael T. Rose ◽  
Peter Geelan-Small ◽  
Khanok-on Amprayn ◽  
...  

Inoculant plant-growth-promoting bacteria are emerging as an important component of sustainable agriculture. There is a need to develop inexpensive methods for enumerating these organisms after their application in the field, to better understand their survival and impacts on yields. Immunoblotting is one potential method to measure viable cells, but the high cost of the conventionally used nylon membranes makes this method prohibitive. In this study, less expensive alternative materials such as filter papers, glossy photo papers, and transparencies for the purpose of colony immunoblotting were evaluated and the best substance was chosen for further studies. Whatman filter paper No. 541 combined with a 0.01 mol·L–1 H2SO4 rinsing step gave similar results to nylon membranes but <20% of the overall cost of the original colony immunoblotting assay. The application of the modified immunoblot method was tested on nonsterile clay soil samples that were spiked with high numbers (>107 CFU·g–1) of the plant-growth-promoting bacteria Pseudomonas fluorescens , Azospirillum brasilense , or Rhizobium leguminosarum . The modified protocol allowed the identification and recovery of over 50% of the inoculated cells of all three strains, amidst a background of the native soil microflora. Subsequently, the survival of P. fluorescens was successfully monitored for several months after application to field-grown rice at Jerilderie, New South Wales, Australia, thus validating the procedure.


2021 ◽  
Vol 9 (9) ◽  
pp. 1988
Author(s):  
Hao Wang ◽  
Runjin Liu ◽  
Ming Pei You ◽  
Martin J. Barbetti ◽  
Yinglong Chen

A vast microbial community inhabits in the rhizosphere, among which, specialized bacteria known as Plant Growth-Promoting Rhizobacteria (PGPR) confer benefits to host plants including growth promotion and disease suppression. PGPR taxa vary in the ways whereby they curtail the negative effects of invading plant pathogens. However, a cumulative or synergistic effect does not always ensue when a bacterial consortium is used. In this review, we reassess the disease-suppressive mechanisms of PGPR and present explanations and illustrations for functional diversity and/or stability among PGPR taxa regarding these mechanisms. We also provide evidence of benefits when PGPR mixtures, rather than individuals, are used for protecting crops from various diseases, and underscore the critical determinant factors for successful use of PGPR mixtures. Then, we evaluate the challenges of and limitations to achieving the desired outcomes from strain/species-rich bacterial assemblages, particularly in relation to their role for plant disease management. In addition, towards locating additive or synergistic outcomes, we highlight why and how the benefits conferred need to be categorized and quantified when different strains/species of PGPR are used in combinations. Finally, we highlight the critical approaches needed for developing PGPR mixtures with improved efficacy and stability as biocontrols for utilization in agricultural fields.


2018 ◽  
Author(s):  
Lorena Jacqueline Gómez-Godínez ◽  
Ernesto Ormeño-Orrillo ◽  
Esperanza Martínez-Romero

ABSTRACTThe free-living soil bacteria that are beneficial for the growth of plants are known as plant growth-promoting rhizobacteria (PGPR). In this work, a multi-species of PGPR bacteria inoculant was designed, which included nitrogen-fixing strains such as Rhizobium phaseoli, Sinorhizobium americanum and Azospirillum brasilense, as well as other plant growth promoting bacteria such as Bacillus subtillis and Methylobacterium extorquens. The multi-species community exerted a beneficial effect on plant seedlings when it was inoculated, greater than the effect observed when inoculating each bacteria individually. Acetylene reduction of maize roots was recorded with the multi-species inoculant, which suggests that nitrogen fixation occurred under these conditions. To analyze the contributions of the different nitrogen-fixing bacteria that were inoculated, a metatranscriptomic analysis was performed. The differential expression analysis revealed that the predominantly nif transcripts of Azospirillum are overexpressed, suggesting that it was responsible for nitrogen fixation in maize. Overall, we analyzed the interaction of a synthetic community, suggesting it as an option, for future formulations of biofertilizers.IMPORTANCEWhile nodulation processes and nitrogen fixation by rhizobia have been well studied, little is known about the interaction between rhizobia and non-leguminous plants such as maize, which is used as a model for this study. Nitrogen fixation in cereals is a long searched goal. Instead of single species inoculants, multi-species inoculation may be more efficient to promote plant growth and fix nitrogen. Metatrascriptomes allowed us to recognize the bacteria responsible for nitrogen fixation in plant rootlets. The study of the function of certain genes may help to understand how microorganisms interact with the root plant, as well as allow a better use of microorganisms for the generation of novel biofertilizers using microbial consortia.


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