scholarly journals Insight Into the Role of PGPR in Sustainable Agriculture and Environment

2021 ◽  
Vol 5 ◽  
Author(s):  
Pratikhya Mohanty ◽  
Puneet Kumar Singh ◽  
Debosmita Chakraborty ◽  
Snehasish Mishra ◽  
Ritesh Pattnaik
Keyword(s):  
Plant Growth ◽  
Seedling Growth ◽  
Mycorrhizal Fungi ◽  
Phosphorus Deficiency ◽  
Sulfur Oxidation ◽  
Plant Growth Promoting Rhizobacteria ◽  
Root Surface ◽  
Growth And Yield ◽  
Root Surface Area ◽  
Copper Chelation

A multitude of roles is played by microbes in food and agriculture that include nutrient cycling and management, organic matter decomposition and fermentation. Plant growth promoting rhizobacteria (PGPR), representing microbial groups and with ability of colonizing plant roots, influence plant growth through various indirect and direct modes in order to promote its growth and/or protect it from diseases or damage due to insect attack. Thus, PGPR research has received renewed interest worldwide. Increasing number of crop-specific PGPR are being commercialized these days. Approaches like seed-inoculation and soil application either alone or in combination with bacterial culture/product for increased nutrient availability through phosphate solubilisation, potassium solubilisation, sulfur oxidation, nitrogen fixation, iron, and copper chelation are gaining popularity. Arbuscular mycorrhizal fungi (AMF) are root fungal symbiont that improve management of abiotic stress such as phosphorus deficiency. PGPR involves roles like production of indole acetic acid (IAA), ammonia (NH3), hydrogen cyanide (HCN), catalase, etc. PGPR also improve nutrient uptake by altering the level of plant hormone that enhances root surface area by increasing its girth and shape, thereby helping in absorbing more nutrients. PGPR facilitate seed germination, seedling growth and crop yield. An array of microbes including Pseudomonas, Azospirillum, Azotobacter, Klebsiella, Enterobacter, Alcaligenes, Arthrobacter, Burkholderia, Bacillus, and Serratia enhance plant growth. Various Pseudomonas sp. have demonstrated significant increase in germination, seedling growth and yield in different agricultural crops, including wheat. Hence, developing a successful crop-specific PGPR formulation, the candidate should possess characteristics like high rhizosphere competence, extensive competitive saprophytic ability, growth enhancing ability, ease of mass production, broad-spectrum action, safety toward the environment and compatibility with other partnering organisms.

scholarly journals Effects and Mechanisms of Symbiotic Microbial Combination Agents to Control Tomato Fusarium Crown and Root Rot Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyue Cai ◽  
Honghai Zhao ◽  
Chen Liang ◽  
Min Li ◽  
Runjin Liu
Keyword(s):  
Enzyme Activity ◽  
Plant Growth ◽  
Root Rot ◽  
Mycorrhizal Fungi ◽  
Plant Growth Promoting Rhizobacteria ◽  
Growth And Yield ◽  
Metabolome Analysis ◽  
Tomato Root ◽  
Tomato Plants ◽  
Crown And Root Rot

This study evaluated the effects and underlying mechanisms of different combinations of plant symbiotic microbes, comprising arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), and Trichoderma spp., on tomato Fusarium crown and root rot (TFCRR) resistance. A total of 54 treatments were applied in a greenhouse pot experiment to tomato (Solanum lycopersicum) seedlings inoculated with or without Funneliformis mosseae (Fm), Rhizophagus intraradices (Ri), Trichoderma virens l40012 (Tv), Trichoderma harzianum l40015 (Th), Bacillus subtilis PS1-3 (Bs), Pseudomonas fluorescens PS2-6 (Pf), and Fusarium oxysporum f. sp. radicis-lycopersici (Fo). The symbioses on the tomato root system were well developed, and the composite symbiont generated by AMF + Trichoderma spp. was observed for the first time. Compared with other treatments, Ri + Bs + Tv and Fm + Pf + Tv stimulated the greatest improvements in tomato growth and yield. The combination Ri + Pf + Th + Fo resulted in the strongest biocontrol effects on TFCRR, followed by the treatments Th + Pf + Fo and Ri + Th + Fo. Compared with the Fo treatment, most inoculation treatments improved photosynthetic performance and significantly increased defense enzyme activity in tomato plants, of which the treatment Ri + Pf + Th + Fo showed the highest enzyme activity. Metabolome analysis detected changes in a total of 1,266 metabolites. The number of up-regulated metabolites in tomato plants inoculated with Ri + Pf + Th and Ri + Pf + Th + Fo exceeded that of the Fo treatment, whereas the number of down-regulated metabolites showed the opposite trend. It is concluded that AMF + Trichoderma + PGPR is the most effective combination to promote resistance to TFCRR in tomato. The up-regulation and down-regulation of metabolites regulated by symbiotic microbial genes may be an important mechanism by which root symbiotic microorganisms promote plant growth, increase yield, and improve disease resistance.

Loblolly pine seedling growth after inoculation with plant growth-promoting rhizobacteria and ozone exposure

2004 ◽  
Vol 34 (7) ◽  
pp. 1410-1416 ◽  
Author(s):  
B L Estes ◽  
S A Enebak ◽  
A H Chappelka
Keyword(s):  
Plant Growth ◽  
Loblolly Pine ◽  
Plant Growth Promoting Rhizobacteria ◽  
Field Trials ◽  
Root Surface ◽  
Ozone Exposure ◽  
Root Surface Area ◽  
Foliar Injury ◽  
Plant Growth Promoting ◽  
Growth Promoting

Plant growth-promoting rhizobacteria promote plant growth and induce biocontrol, but are affected by soil type, water stress, microbial competition, and environmental conditions. One unexplored factor is the interaction of rhizobacteria-inoculated plants exposed to ozone. Loblolly pine (Pinus taeda L.) seeds were inoculated with either Bacillus subtilis (Ehrenberg) Cohn or Paenibacillus macerans (Schardinger) Ash. In field trials, 4-week-old seedlings were exposed for 12 weeks to carbon-filtered (CF ≈ 12 ppb), 1× (≈46 ppb), or 2× (≈97 ppb) ozone for 12 h·d–1 in open-top chambers (OTC) in 1998 and 1999. In three greenhouse trials, 5-week-old seedlings were exposed to ozone at 0× (≈8 ppb), 1× (≈105 ppb), 2× (≈199 ppb), and 3× (≈298 ppb) for 4 h·d–1, 5 d·week–1 for 8 weeks in continuously stirred tank reactors (CSTR). In both the CSTRs and the OTCs, ozone-exposed seedlings exhibited 20%–50% less biomass and more foliar injury as compared with nonexposed seedlings. In CSTRs, at the 3× exposure, B. subtilis-inoculated seedlings had 12% less foliar injury than noninoculated seedlings. Foliar injury was 65% less for B. subtilis-treated seedlings in 1998, and root surface area, total root length, and root diameter was 25%–35% greater when seedlings were exposed to 2× ozone in the OTCs. This is the first report of rhizobacteria protecting seedlings against the negative effects of ozone exposure.

scholarly journals Amelioration of water deficiency stress in roselle (Hibiscus sabdariffa) by arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria

2021 ◽  
Vol 49 (2) ◽  
pp. 11987
Author(s):  
Sara SANAYEI ◽  
Morteza BARMAKI ◽  
Ali EBADI ◽  
Mousa TORABI-GIGLOU
Keyword(s):  
Plant Growth ◽  
Seed Yield ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Plant Growth Promoting Rhizobacteria ◽  
Growth And Yield ◽  
Water Deficiency ◽  
Plant Growth Promoting ◽  
Growth Promoting

Belowground interactions between plant roots, arbuscular mycorrhizal fungi (AMFs), and plant growth-promoting rhizobacteria (PGPR) can improve growth and yield under abiotic stress conditions. A pot factorial experiment based on completely randomized design with three replications was conducted to investigate the effects of AMFs (without inoculation as control, inoculation with Funneliformis mosseae and Funneliformis intraradices) and PGPRs (without inoculation as control Pseudomonas fluorescens p-169 inoculation) on roselle (Hibiscus sabdariffa L.) grown under water deficiency stress (WDS) [90% (I1), 75% (I2), 50% (I3), and 25% (I4) of field capacity as well-watered, mild, moderate, and severe stress, respectively]. The results showed that by applying WDS, the plant growth properties such as root and sepals’ dry weight, 1000-seed weight, seed yield, chlorophyll a, b, and total, carotenoids, and leaf water content was significantly reduced. The application of AMFs and PGPR under WDS conditions increased 1000-seed weight, seed yield. In response to WDS osmotic adjustment were provided in Roselle and under stress conditions. The highest seed yield was found under well-watered treatment by inoculation of F. mosseae without PGPR and the application of Pseudomonas fluorescens (6.37 and 6.51 g/plant, respectively). These results suggesting the antagonistic effects of AMFs and PGPR. AMFs inoculation under severe stress increased sepals dry weight compared to the non-inoculation. In conclusion, increased activity of enzymatic antioxidants and higher production of non-enzymatic antioxidant compounds, as well as photosynthetic pigments in symbiotic association with AMFs, can alleviate reactive oxygen species damage resulting in increased growth and yield parameters and improve water stress tolerance.

scholarly journals Agricultural Sustainability: Microbial Biofertilizers in Rhizosphere Management

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 163
Author(s):  
Oluwaseun Adeyinka Fasusi ◽  
Cristina Cruz ◽  
Olubukola Oluranti Babalola
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
Soil Microorganisms ◽  
Agricultural Sector ◽  
Cost Effective ◽  
Plant Growth Promoting Rhizobacteria ◽  
Growth And Yield ◽  
Chemical Fertilizers ◽  
Plant Growth Promoting ◽  
High Level

The world’s human population continues to increase, posing a significant challenge in ensuring food security, as soil nutrients and fertility are limited and decreasing with time. Thus, there is a need to increase agricultural productivity to meet the food demands of the growing population. A high level of dependence on chemical fertilizers as a means of increasing food production has damaged the ecological balance and human health and is becoming too expensive for many farmers to afford. The exploitation of beneficial soil microorganisms as a substitute for chemical fertilizers in the production of food is one potential solution to this conundrum. Microorganisms, such as plant growth-promoting rhizobacteria and mycorrhizal fungi, have demonstrated their ability in the formulation of biofertilizers in the agricultural sector, providing plants with nutrients required to enhance their growth, increase yield, manage abiotic and biotic stress, and prevent phytopathogens attack. Recently, beneficial soil microbes have been reported to produce some volatile organic compounds, which are beneficial to plants, and the amendment of these microbes with locally available organic materials and nanoparticles is currently used to formulate biofertilizers to increase plant productivity. This review focuses on the important role performed by beneficial soil microorganisms as a cost-effective, nontoxic, and eco-friendly approach in the management of the rhizosphere to promote plant growth and yield.

scholarly journals Plant Growth-Promoting Microorganisms in Coffee Production: From Isolation to Field Application

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1531
Author(s):  
Narcisa Urgiles-Gómez ◽  
María Eugenia Avila-Salem ◽  
Paúl Loján ◽  
Max Encalada ◽  
Leslye Hurtado ◽  
...  
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Plant Growth Promoting Rhizobacteria ◽  
Agroforestry Systems ◽  
Field Application ◽  
Coffee Production ◽  
Coffee Agroforestry ◽  
Plant Growth Promoting ◽  
Growth Promoting

Coffee is an important, high-value crop because its roasted beans are used to produce popular beverages that are consumed worldwide. Coffee plantations exist in over 70 countries and constitute the main economic activity of approximately 125 million people. Currently, there is global concern regarding the excessive use of agrochemicals and pesticides in agriculture, including coffee crops. This situation has motivated researchers, administrators, and farmers to seek ecologically friendly alternatives to decrease the use of synthetic fertilizers and pesticides. In the last decades, multiple studies of the rhizosphere, at the chemical, physical and biological levels, have improved our understanding of the importance of beneficial microorganisms to plant health and growth. This review aims to summarize the state of the use of plant growth-promoting microorganisms (PGPM) in coffee production, where the most extensively studied microorganisms are beneficial plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF). This review also contains information on PGPM, in regard to plantations at different latitudes, isolation techniques, mass multiplication, formulation methods, and the application of PGPM in nurseries, monoculture, and coffee agroforestry systems. Finally, this review focuses on relevant research performed during the last decade that can help us improve sustainable coffee production.

scholarly journals Morphological and Metabolite Responses of Potatoes under Various Phosphorus Levels and Their Amelioration by Plant Growth-Promoting Rhizobacteria

2021 ◽  
Vol 22 (10) ◽  
pp. 5162
Author(s):  
Leangsrun Chea ◽  
Birgit Pfeiffer ◽  
Dominik Schneider ◽  
Rolf Daniel ◽  
Elke Pawelzik ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Shoot Biomass ◽  
Root Surface Area ◽  
Limiting Factor ◽  
P Availability ◽  
P Deficiency ◽  
Plant Growth Promoting ◽  
Growth Promoting

Low phosphorus (P) availability is a major limiting factor for potatoes. P fertilizer is applied to enhance P availability; however, it may become toxic when plants accumulate at high concentrations. Therefore, it is necessary to gain more knowledge of the morphological and biochemical processes associated with P deficiency and toxicity for potatoes, as well as to explore an alternative approach to ameliorate the P deficiency condition. A comprehensive study was conducted (I) to assess plant morphology, mineral allocation, and metabolites of potatoes in response to P deficiency and toxicity; and (II) to evaluate the potency of plant growth-promoting rhizobacteria (PGPR) in improving plant biomass, P uptake, and metabolites at low P levels. The results revealed a reduction in plant height and biomass 60–80% under P deficiency compared to P optimum. P deficiency and toxicity conditions also altered the mineral concentration and allocation in plants due to nutrient imbalance. The stress induced by both P deficiency and toxicity was evident from an accumulation of proline and total free amino acids in young leaves and roots. Furthermore, root metabolite profiling revealed that P deficiency reduced sugars by 50–80% and organic acids by 20–90%, but increased amino acids by 1.5–14.8 times. However, the effect of P toxicity on metabolic changes in roots was less pronounced. Under P deficiency, PGPR significantly improved the root and shoot biomass, total root length, and root surface area by 32–45%. This finding suggests the potency of PGPR inoculation to increase potato plant tolerance under P deficiency.

Manipulation of rhizosphere organisms to enhance glomalin production and C sequestration: Pitfalls and promises

2014 ◽  
Vol 94 (6) ◽  
pp. 1025-1032 ◽  
Author(s):  
F. L. Walley ◽  
A. W. Gillespie ◽  
Adekunbi B. Adetona ◽  
J. J. Germida ◽  
R. E. Farrell
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
Plant Growth Promoting Rhizobacteria ◽  
C Sequestration ◽  
Ionization Mass ◽  
Edge Structure ◽  
Organic C ◽  
Soil C ◽  
N Storage ◽  
C And N

Walley, F. L., Gillespie, A. W., Adetona, A. B., Germida, J. J. and Farrell, R. E. 2014. Manipulation of rhizosphere organisms to enhance glomalin production and C-sequestration: Pitfalls and promises. Can. J. Plant Sci. 94: 1025–1032. Arbuscular mycorrhizal fungi (AMF) reportedly produce glomalin, a glycoprotein that has the potential to increase soil carbon (C) and nitrogen (N) storage. We hypothesized that interactions between rhizosphere microorganisms, such as plant growth-promoting rhizobacteria (PGPR), and AMF, would influence glomalin production. Our objectives were to determine the effects of AMF/PGPR interactions on plant growth and glomalin production in the rhizosphere of pea (Pisum sativum L.) with the goal of enhancing C and N storage in the rhizosphere. One component of the study focussed on the molecular characterization of glomalin and glomalin-related soil protein (GRSP) using complementary synchrotron-based N and C X-ray absorption near-edge structure (XANES) spectroscopy, pyrolysis field ionization mass spectrometry (Py-FIMS), and proteomics techniques to characterize specific organic C and N fractions associated with glomalin production. Our research ultimately led us to conclude that the proteinaceous material extracted, and characterized in the literature, as GRSP is not exclusively of AMF origin. Our research supports the established concept that GRSP is important to soil quality, and C and N storage, irrespective of origin. However, efforts to manipulate this important soil C pool will remain compromised until we more clearly elucidate the chemical nature and origin of this resource.

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