Microbiome Management by Biological and Chemical Treatments in Maize Is Linked to Plant Health

The targeted application of plant growth-promoting rhizobacteria (PGPR) provides the key for a future sustainable agriculture with reduced pesticide application. PGPR interaction with the indigenous microbiota is poorly understood, but essential to develop reliable applications. Therefore, Stenotrophomonas rhizophila SPA-P69 was applied as a seed coating and in combination with a fungicide based on the active ingredients fludioxonil, metalaxyl-M, captan and ziram. The plant performances and rhizosphere compositions of treated and non-treated maize plants of two field trials were analyzed. Plant health was significantly increased by treatment; however, overall corn yield was not changed. By applying high-throughput amplicon sequencing of the 16S rRNA and the ITS genes, the bacterial and fungal changes in the rhizosphere due to different treatments were determined. Despite the fact that treatments had a significant impact on the rhizosphere microbiota (9–12%), the field site was identified as the main driver (27–37%). The soil microbiota composition from each site was significantly different, which explains the site-specific effects. In this study we were able to show the first indications how PGPR treatments increase plant health via microbiome shifts in a site-specific manner. This way, first steps towards a detailed understanding of PGPRs and developments of consistently efficient applications in diverse environments are made.

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Microbiome Management by Biological and Chemical Treatments in Maize is Linked to Plant Health

10.20944/preprints202008.0471.v1 ◽

2020 ◽

Author(s):

Peter Kusstatscher ◽

Wisnu Adi Wicaksono ◽

Dhivya P. Thenappan ◽

Eveline Adam ◽

Henry Müller ◽

...

Keyword(s):

Plant Growth Promoting Rhizobacteria ◽

Amplicon Sequencing ◽

Field Trials ◽

Plant Health ◽

Plant Performance ◽

Corn Yield ◽

Site Specific ◽

Main Driver ◽

Plant Growth Promoting ◽

Stenotrophomonas Rhizophila

The targeted application of plant growth promoting rhizobacteria (PGPR) provides the key for a future sustainable agriculture with reduced pesticide application. PGPR interaction with the indigenous microbiota is poorly understood but essential to develop reliable applications. Therefore, Stenotrophomonas rhizophila SPA-P69 was applied as seed coating and in combination with a fungicide based on the active ingredients fludioxonil, metalaxyl-M, captan and ziram. Plant performance and rhizosphere composition of treated and non-treated maize plants of two field trials were analyzed. Plant health was significantly increased by treatment; however overall corn yield was not changed. By applying high-throughput amplicon sequencing of the 16S rRNA and the ITS genes, the bacterial and fungal changes in the rhizosphere due to different treatments were determined. Despite treatments had a significant impact on the rhizosphere microbiota (9- 12%), the field site was identified as main driver (27- 37%). Soil microbiota composition from each site was significantly different, which explains the site-specific effects. In this study we were able to show first indications how PGPR treatments increase plant health via microbiome shifts in a site-specific manner. This way first steps towards a detailed understanding of PGPRs and developments of consistently efficient applications in diverse environments are set.

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C4 Bacterial Volatiles Improve Plant Health

Pathogens ◽

10.3390/pathogens10060682 ◽

2021 ◽

Vol 10 (6) ◽

pp. 682

Author(s):

Bruno Henrique Silva Dias ◽

Sung-Hee Jung ◽

Juliana Velasco de Castro Oliveira ◽

Choong-Min Ryu

Keyword(s):

Plant Growth ◽

Volatile Compounds ◽

Large Scale ◽

Growth Promotion ◽

Plant Growth Promoting Rhizobacteria ◽

Plant Health ◽

Systemic Resistance ◽

Potential Applications ◽

Plant Growth Promoting ◽

Bacterial Volatiles

Plant growth-promoting rhizobacteria (PGPR) associated with plant roots can trigger plant growth promotion and induced systemic resistance. Several bacterial determinants including cell-wall components and secreted compounds have been identified to date. Here, we review a group of low-molecular-weight volatile compounds released by PGPR, which improve plant health, mostly by protecting plants against pathogen attack under greenhouse and field conditions. We particularly focus on C4 bacterial volatile compounds (BVCs), such as 2,3-butanediol and acetoin, which have been shown to activate the plant immune response and to promote plant growth at the molecular level as well as in large-scale field applications. We also disc/ uss the potential applications, metabolic engineering, and large-scale fermentation of C4 BVCs. The C4 bacterial volatiles act as airborne signals and therefore represent a new type of biocontrol agent. Further advances in the encapsulation procedure, together with the development of standards and guidelines, will promote the application of C4 volatiles in the field.

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Prospect and Challenges for Sustainable Management of Climate Change-Associated Stresses to Soil and Plant Health by Beneficial Rhizobacteria

Stresses ◽

10.3390/stresses1040015 ◽

2021 ◽

Vol 1 (4) ◽

pp. 200-222

Author(s):

Aniruddha Sarker ◽

Most. Waheda Rahman Ansary ◽

Mohammad Nabil Hossain ◽

Tofazzal Islam

Keyword(s):

Climate Change ◽

Relevant Literature ◽

Sustainable Use ◽

Soil Health ◽

Plant Growth Promoting Rhizobacteria ◽

Critical Discussion ◽

Climatic Conditions ◽

Plant Health ◽

Stressful Environment ◽

Plant Growth Promoting

Climate change imposes biotic and abiotic stresses on soil and plant health all across the planet. Beneficial rhizobacterial genera, such as Bacillus, Pseudomonas, Paraburkholderia, Rhizobium, Serratia, and others, are gaining popularity due to their ability to provide simultaneous nutrition and protection of plants in adverse climatic conditions. Plant growth-promoting rhizobacteria are known to boost soil and plant health through a variety of direct and indirect mechanisms. However, various issues limit the wider commercialization of bacterial biostimulants, such as variable performance in different environmental conditions, poor shelf-life, application challenges, and our poor understanding on complex mechanisms of their interactions with plants and environment. This study focused on detecting the most recent findings on the improvement of plant and soil health under a stressful environment by the application of beneficial rhizobacteria. For a critical and systematic review story, we conducted a non-exhaustive but rigorous literature survey to assemble the most relevant literature (sorting of a total of 236 out of 300 articles produced from the search). In addition, a critical discussion deciphering the major challenges for the commercialization of these bioagents as biofertilizer, biostimulants, and biopesticides was undertaken to unlock the prospective research avenues and wider application of these natural resources. The advancement of biotechnological tools may help to enhance the sustainable use of bacterial biostimulants in agriculture. The perspective of biostimulants is also systematically evaluated for a better understanding of the molecular crosstalk between plants and beneficial bacteria in the changing climate towards sustainable soil and plant health.

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The SAGE genetic toolkit enables highly efficient, iterative site-specific genome engineering in bacteria

10.1101/2020.06.28.176339 ◽

2020 ◽

Author(s):

Joshua R. Elmore ◽

Gara N. Dexter ◽

Ryan Francis ◽

Lauren Riley ◽

Jay Huenemann ◽

...

Keyword(s):

Genome Engineering ◽

Dynamic Range ◽

Plant Growth Promoting Rhizobacteria ◽

Crop Productivity ◽

Site Specific ◽

Modern Agriculture ◽

Site Specific Integration ◽

Promoter Library ◽

Plant Growth Promoting ◽

Dna Maintenance

AbstractSustainable enhancements to crop productivity and increased resilience to adverse conditions are critical for modern agriculture, and application of plant growth promoting rhizobacteria (PGPR) is a promising method to achieve these goals. However, many desirable PGPR traits are highly regulated in their native microbe, limited to certain plant rhizospheres, or insufficiently active for agricultural purposes. Synthetic biology can address these limitations, but its application is limited by availability of appropriate tools for sophisticated, high-throughput genome engineering that function in environments where selection for DNA maintenance is impractical. Here we present an orthogonal, Serine-integrase Assisted Genome Engineering (SAGE) system, which enables iterative, site-specific integration of up to 10 different DNA constructs at efficiency on par or better than replicating plasmids. SAGE does not require use of replicating plasmids to deliver recombination machinery, and employs a secondary serine-integrase to excise and recycle selection markers. Furthermore, unlike the widely utilized pBBR1 origin, DNA transformed using SAGE is stable without selection. We highlight SAGE’s utility by constructing a 287-member constitutive promoter library with a ∼40,000-fold dynamic range in P. fluorescens SBW25. We show that SAGE functions robustly in diverse α- and γ-proteobacteria, thus providing evidence that it will be broadly useful for engineering industrial or environmental bacteria.

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

Canadian Journal of Forest Research ◽

10.1139/x04-026 ◽

2004 ◽

Vol 34 (7) ◽

pp. 1410-1416 ◽

Cited By ~ 9

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·d1 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·d1, 5 d·week1 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.

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Selecting Bacterial Antagonists for Cucurbit Downy Mildew and Developing an Effective Application Method

Plant Disease ◽

10.1094/pdis-01-17-0058-re ◽

2018 ◽

Vol 102 (3) ◽

pp. 628-639 ◽

Cited By ~ 2

Author(s):

Li Zheng ◽

Chun Gu ◽

Jing Cao ◽

Shi-mo Li ◽

Guang Wang ◽

...

Keyword(s):

Downy Mildew ◽

Bacillus Pumilus ◽

Foliar Spray ◽

Plant Growth Promoting Rhizobacteria ◽

Field Trials ◽

Cucurbit Downy Mildew ◽

Naturally Occurring ◽

Bacterial Antagonists ◽

Plant Growth Promoting ◽

Growth Promoting

To identify new bacterial antagonists for cucurbit downy mildew (CDM) caused by Pseudoperonospora cubensis, 163 bacterial isolates were recovered from different microenvironments of field-grown cucumber plants. In the greenhouse, 19 representative isolates were applied to cucumber plants as a foliar spray (FS); 7 isolates achieved the efficacy over 60% against CDM, with 5 (DS22, HS10, DP14, HP4, and DS57) identified as Bacillus pumilus, B. licheniformis, Enterobacter sp., Bacillus sp., and Stenotrophomonas maltophilia, respectively. Strains DP14, DS22, and HS10 were assessed for their biocontrol effect on naturally occurring CDM in 2-year field trials (2010 and 2011), in which their overall efficacy relative to that of propamocarb was 106.25 to 117.17% with foliar spray plus root drench (FS+RD) but only 70.98 to 84.03% with FS. Coincidently, DP14 and HS10 applied as root drench (RD) alone also significantly reduced CDM. Under field conditions, DP14, DS22, and HS10 all successfully colonized cucumber leaves and the rhizosphere, and also significantly increased fruit yield by 37.60 to 51.03%, as well as nutrient levels. Taken together, Enterobacter sp. DP14, B. licheniformis HS10, and B. pumilus DS22 are plant-growth-promoting rhizobacteria effective in controlling CDM in the field, whose efficacy increased with FS+RD compared with FS alone.

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Insights into Chemical Interaction between Plants and Microbes and its Potential Use in Soil Remediation

BioScientific Review ◽

10.32350/bsr.0104.05 ◽

2019 ◽

Vol 01 (04) ◽

pp. 39-45

Author(s):

Kaneez Fatima

Keyword(s):

Plant Growth ◽

Chemical Interaction ◽

Plant Defence ◽

Hydrolytic Enzymes ◽

Plant Growth Promoting Rhizobacteria ◽

Plant Health ◽

Degrading Bacteria ◽

Plant Growth Promoting ◽

Health Promoting ◽

Growth Promoting

Soil bacteria are very vital and they are frequently used in production of crop. Chemical dialogues between bacteria and plant roots result in the proliferation and biofilm formation of plant growth promoting and contaminant degrading bacteria. Plant-bacterial interactions in the rhizosphere are the determinants of plant health and soil fertility. Plant growth promoting rhizobacteria (PGPR) which is also known as plant health promoting rhizobacteria (PHPR) or nodule promoting rhizobacteria (NPR). It can benefit the host plant directly by enhancing plant growth or indirectly by producing hydrolytic enzymes and by priming plant defence. This review elaborates the effect of plant and bacterial products on the remediation of contaminated soil.

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Application of Growth-promoting Rhizobacteria to Transplant Plug and Seed

HortScience ◽

10.21273/hortsci.30.4.750a ◽

1995 ◽

Vol 30 (4) ◽

pp. 750A-750 ◽

Cited By ~ 1

Author(s):

George Lazarovits

Keyword(s):

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Field Trials ◽

Model Systems ◽

Screening Methods ◽

Host Defenses ◽

Plant Growth Promoting ◽

Stimulate Plant Growth ◽

Growth Promoting ◽

Selection Of

Plant growth-promoting rhizobacteria (PGPR) enhance plant development by many mechanisms. Indirect growth effects result from PGPR activities that displace soilborne pathogens and thereby reduce disease. Direct effects include improved nutrition, reduced disease due to activation of host defenses, and bacterial production of phytohormones. An understanding of the mode of action is essential for exploitation of PGPR for field use. For instance, bacteria that act as biological control agents can only be of benefit at locations where disease occurs. PGPR that stimulate plant growth directly will likely have more universal uses and greater impacts. Thus, we have been developing model systems for identifying PGPR with such traits. In this presentation, the effects of bacterization of tissue culture-grown plants, plug transplants, and seed with a growth-promoting Pseudomonas sp. (PsJN) will be described. Potential uses for this and other PGPR will also be identified. The talk will consider the advantages and limitations of: a) screening methods used for selection of PGPR, b) model systems available for studying the mechanisms of action, and c) why transplants offer an ideal delivery system for rhizobacteria. Results from field trials with PGPR with different modes of action will be presented and their future role in agriculture considered.

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Biological Control of Meloidogyne incognita by Spore-forming Plant Growth-promoting Rhizobacteria on Cotton

Plant Disease ◽

10.1094/pdis-09-16-1369-re ◽

2017 ◽

Vol 101 (5) ◽

pp. 774-784 ◽

Cited By ~ 31

Author(s):

Ni Xiang ◽

Kathy S. Lawrence ◽

Joseph W. Kloepper ◽

Patricia A. Donald ◽

John A. McInroy ◽

...

Keyword(s):

Biological Control ◽

Plant Growth ◽

Meloidogyne Incognita ◽

Plant Growth Promoting Rhizobacteria ◽

Field Trials ◽

Parasitic Nematodes ◽

Subtilis Strain ◽

Plant Growth Promoting ◽

Growth Promoting

In the past decade, increased attention has been placed on biological control of plant-parasitic nematodes using various fungi and bacteria. The objectives of this study were to evaluate the potential of 662 plant growth-promoting rhizobacteria (PGPR) strains for mortality to Meloidogyne incognita J2 in vitro and for nematode management in greenhouse, microplot, and field trials. Results indicated that the mortality of M. incognita J2 by the PGPR strains ranged from 0 to 100% with an average of 39%. Among the PGPR strains examined, 212 of 662 strains (or 33%) caused significantly greater mortality percent of M. incognita J2 than the untreated control. Bacillus was the major genus initiating a greater mortality percentage when compared with the other genera. In subsequent trials, B. velezensis strain Bve2 reduced M. incognita eggs per gram of cotton root in the greenhouse trials at 45 days after planting (DAP) similarly to the commercial standards Abamectin and Clothianidin plus B. firmus I-1582. Bacillus mojavensis strain Bmo3, B. velezensis strain Bve2, B. subtilis subsp. subtilis strain Bsssu3, and the Mixture 2 (Abamectin + Bve2 + B. altitudinis strain Bal13) suppressed M. incognita eggs per gram of root in the microplot at 45 DAP. Bacillus velezensis strains Bve2 and Bve12 also increased seed-cotton yield in the microplot and field trials. Overall, results indicate that B. velezensis strains Bve2 and Bve12, B. mojavensis strain Bmo3, and Mixture 2 have potential to reduce M. incognita population density and to enhance growth of cotton when applied as in-furrow sprays at planting.

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