Plant Growth Promotion Driven by a Novel Caulobacter Strain

Soil microbial communities hold great potential for sustainable and ecologically compatible agriculture. Although numerous plant-beneficial bacterial strains from a wide range of taxonomic groups have been reported, very little evidence is available on the plant-beneficial role of bacteria from the genus Caulobacter. Here, the mode of action of a Caulobacter strain, designated RHG1, which had originally been identified through a microbial screen for plant growth-promoting (PGP) bacteria in maize (Zea mays), is investigated in Arabidopsis thaliana. RHG1 colonized both roots and shoots of Arabidopsis, promoted lateral root formation in the root, and increased leaf number and leaf size in the shoot. The genome of RHG1 was sequenced and was utilized to look for PGP factors. Our data revealed that the bacterial production of nitric oxide, auxins, cytokinins, or 1-aminocyclopropane-1-carboxylate deaminase as PGP factors could be excluded. However, the analysis of brassinosteroid mutants suggests that an unknown PGP mechanism is involved that impinges directly or indirectly on the pathway of this growth hormone.

Download Full-text

Diversity and Plant Growth-Promoting Potential of (un)culturable Bacteria in the Hedera Helix Phylloplane

10.21203/rs.3.rs-52944/v1 ◽

2020 ◽

Author(s):

Vincent Stevens ◽

Sofie Thijs ◽

Jaco Vangronsveld

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Growth Media ◽

Culturable Bacteria ◽

Bacterial Strains ◽

Hedera Helix ◽

Plant Growth Promoting ◽

Diverse Community ◽

And Function

Abstract BackgroundAn abundant and diverse community of microorganisms naturally exists on the phylloplane, the surface of leaves. It is one of the most prevalent microbial habitats on earth and bacteria are by far the most abundant members, living in a community that is highly dynamic. To increase our knowledge about the diversity and function of microbial communities living in the phylloplane, culture-dependent and -independent approaches help us a great deal.ResultsHere we isolated bacteria from the phylloplane of Hedera helix (common ivy), a widespread evergreen, using five different growth media. We further included a comparison with the uncultured phylloplane, which we show to contain the highest intra-sample diversity. Inter-sample bacterial diversity shifts from growth media most rich in nutrients to those which are more selective. The four major phyla Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes comprised the vast majority of phyla in the uncultured H. helix phylloplane, which furthermore were fully represented within growth medium samples. The plant growth promotion (PGP) profile we obtained by testing 200 isolates can help to select candidates with advantageous traits within various microbe-assisted approaches. Our isolation effort also resulted in a significant collection of bacterial strains underrepresented in public databases, mostly from the phylum Actinobacteria. ConclusionsThis study contributes as a case study of bacterial culturability and its relation with functional characteristics such as PGP potential which also is an important step towards understanding the ecological and functional role of microbial members living in the H. helix phylloplane.

Download Full-text

PGPR Characteristics of Rhizospheric Bacteria to Understand the Mechanisms of Faba Bean Growth

Proceedings ◽

10.3390/proceedings2020066027 ◽

2021 ◽

Vol 66 (1) ◽

pp. 27

Author(s):

Rim Tinhinen Maougal ◽

Maya Kechid ◽

Chaima Ladjabi ◽

Abdelhamid Djekoun

Keyword(s):

Plant Growth ◽

Faba Bean ◽

Biochemical Characterization ◽

Plant Growth Promoting Rhizobacteria ◽

Bacterial Strains ◽

Rhizospheric Bacteria ◽

Plant Growth Promoting ◽

Pgpr Traits ◽

Taxonomic Groups ◽

High Degree

Rhizobacteria play an important role in maintaining soil balance. Among these bacteria, there are those taht have shown their ability to promote the growth of plants, known as Plant Growth Promoting Rhizobacteria (PGPR). In our work, we are interested in characterizing 110 bacterial strains isolated in the field in the region of Ben Badis (Constantine Algeria) from 5 varieties of faba bean. Phenotypic and biochemical characterization showed that most of the isolates are cream-colored, slightly raised, flat and opaque, Gram−, catalase+ and oxidase−, and Bacillus form. PCA analysis allowed us to select 40 isolates with a high degree of variability to continue our work. The results obtained have directed us towards different taxonomic groups (rhizobium, Pseudomonas, Bacillus etc.). The evaluation of the PGPR potential of bacteria (phytostimulation, biofertilization and biocontrol), showed that 100% of bacteria are able to produce auxin at different concentrations, with the highest concentration (177.77 µg/mL) for the isolate 6, and that more than 50% of isolates are capable of producing nitrogen, ammonia and phytate mineralization. These PGPR traits have a direct effect on plant growth of five varieties of the faba bean and can be used to select the best performing bacteria for inoculation tests.

Download Full-text

The Effects of Plant Growth-Promoting Bacteria with Biostimulant Features on the Growth of a Local Onion Cultivar and a Commercial Zucchini Variety

Agronomy ◽

10.3390/agronomy11050888 ◽

2021 ◽

Vol 11 (5) ◽

pp. 888

Author(s):

Giorgia Novello ◽

Patrizia Cesaro ◽

Elisa Bona ◽

Nadia Massa ◽

Fabio Gosetti ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Global Market ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Mineral Concentration ◽

Positive Effects ◽

Plant Growth Promoting ◽

Onion Cultivar ◽

Growth Promoting

The reduction of chemical inputs due to fertilizer and pesticide applications is a target shared both by farmers and consumers in order to minimize the side effects for human and environmental health. Among the possible strategies, the use of biostimulants has become increasingly important as demonstrated by the fast growth of their global market and by the increased rate of registration of new products. In this work, we assessed the effects of five bacterial strains (Pseudomonas fluorescens Pf4, P. putida S1Pf1, P. protegens Pf7, P. migulae 8R6, and Pseudomonas sp. 5Vm1K), which were chosen according to their previously reported plant growth promotion traits and their positive effects on fruit/seed nutrient contents, on a local onion cultivar and on zucchini. The possible variations induced by the inoculation with the bacterial strains on the onion nutritional components were also evaluated. Inoculation resulted in significant growth stimulation and improvement of the mineral concentration of the onion bulb, induced particularly by 5Vm1K and S1Pf1, and in different effects on the flowering of the zucchini plants according to the bacterial strain. The present study provides new information regarding the activity of the five plant growth-promoting bacteria (PGPB) strains on onion and zucchini, two plant species rarely considered by the scientific literature despite their economic relevance.

Download Full-text

Plant growth promotion properties of bacterial strains isolated from the rhizosphere of the Jerusalem artichoke (Helianthus tuberosusL.) adapted to saline–alkaline soils and their effect on wheat growth

Canadian Journal of Microbiology ◽

10.1139/cjm-2016-0511 ◽

2017 ◽

Vol 63 (3) ◽

pp. 228-237 ◽

Cited By ~ 11

Author(s):

Xiaolin Liu ◽

Xiangyue Li ◽

Yan Li ◽

Runzhi Li ◽

Zhihong Xie

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Yellow River ◽

Growth Promotion ◽

Jerusalem Artichoke ◽

Yellow River Delta ◽

Bacterial Strains ◽

Wheat Growth ◽

The Yellow River Delta ◽

Plant Growth Promoting

The Jerusalem artichoke (JA; Helianthus tuberosus), known to be tolerant to saline–alkaline soil conditions, has been cultivated for many years in the Yellow River delta, Shandong Province coastal zone, in China. The aim of our study was to isolate nitrogen-fixing bacteria colonizing the rhizosphere of JA and to characterize other plant growth promotion properties. The ultimate goal was to identify isolates that could be used as inoculants benefiting an economic crop, in particular for improving wheat growth production in the Yellow River delta. Bacterial strains were isolated from the rhizosphere soil of JA on the basis of growth on nitrogen-free Ashby medium. Identification and phylogenetic analysis was performed after nucleotide sequencing of 16S rRNA gene. Plant-growth-promoting traits, such as nitrogen fixation activity, phosphate solubilization activity, indole-3-acetic acid production, were determined using conventional methods. Eleven strains were isolated and 6 of them were further examined for their level of salt tolerance and their effect on plant growth promotion. Inoculation of Enterobacter sp. strain N10 on JA and wheat led to significant increases in both root and shoot dry mass and shoot height. Enterobacter sp. strain N10 appeared to be the best plant-growth-promoting rhizobacteria to increase wheat productivity in future field applications.

Download Full-text

Plant growth promotion of barley (Hordeum vulgare L.) by potassium solubilizing bacteria with multifarious plant growth promoting attributes

Plant Science Today ◽

10.14719/pst.1377 ◽

2021 ◽

Vol 8 (sp1) ◽

pp. 17-24

Author(s):

Tanvir Kaur ◽

Rubee Devi ◽

Divjot Kour ◽

Ashok Yadav ◽

Ajar Nath Yadav

Keyword(s):

Plant Growth ◽

Environmental Sustainability ◽

Growth Promotion ◽

Growth Parameters ◽

Sugar Content ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Hordeum Vulgare L ◽

Plant Growth Promoting ◽

Growth Promoting

Potassium (K) is the foremost macronutrients for growth of plant, soil health and fertility. The huge application of NPK chemical fertilizers negatively impacts the economy and is a threat to environmental sustainability. The rapid depletion of K mineral in soil is due to the application of agrochemicals agricultural fields for the production of crops in India. In present investigation, K-solubilizing microbes (KSM) were isolated and enumerated from cereal crops growing in Sirmour Himachal Pradesh. A total 125 bacteria were isolated and screened for K- solubilization on Aleksandrov agar plates and found that 31 bacterial strains exhibited K-solubilization. These 31 K-solubilizing strains of bacteria were additionally screened for other plant growth promoting (PGP) potential including solubilization of minerals, production of siderophores, ammonia, hydrogen cyanide and indole acetic acids. The performance of an efficient K-solubilizer was evaluated for plant growth promoting ability in pot assay under in vitro conditions. The strain EU-LWNA-25 positively influenced shoot length, fresh weight, carotenoids and total sugar content than the full dose, half dose and control. The strain enhancing physiological and growth parameters was identified by BLASTn analysis as Pseudomonas gessardii EU-LWNA-25. K-solubilizing plant growth promoting bacteria could be suitable bioinoculants for Rabi seasonal crops and overcomes the challenges of sustainable agriculture in K-deficient soil.

Download Full-text

Plant Growth Promoting Abilities of Novel Burkholderia-Related Genera and Their Interactions With Some Economically Important Tree Species

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.618305 ◽

2021 ◽

Vol 5 ◽

Author(s):

Munusamy Madhaiyan ◽

Govindan Selvakumar ◽

Tan HianHwee Alex ◽

Lin Cai ◽

Lianghui Ji

Keyword(s):

Plant Growth ◽

Oil Palm ◽

Tree Species ◽

Growth Promotion ◽

Nitrogenase Activity ◽

Acc Deaminase ◽

Bacterial Strains ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Promote Plant Growth

A survey of bacterial endophytes associated with the leaves of oil palm and acacias resulted in the isolation of 19 bacterial strains belonging to the genera Paraburkholderia, Caballeronia, and Chitinasiproducens, which are now regarded as distinctively different from the parent genus Burkholderia. Most strains possessed one or more plant growth promotion (PGP) traits although nitrogenase activity was present in only a subset of the isolates. The diazotrophic Paraburkholderia tropica strain S39-2 with multiple PGP traits and the non-diazotrophic Chitinasiproducens palmae strain JS23T with a significant level of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were selected to investigate the influence of bacterial inoculation on some economically important tree species. Microscopic examination revealed that P. tropica S39-2 was rhizospheric as well as endophytic while C. palmae JS23T was endophytic. P. tropica strain S39-2 significantly promoted the growth of oil palm, eucalyptus, and Jatropha curcas. Interestingly, the non-diazotrophic, non-auxin producing C. palmae JS23T strain also significantly promoted the growth of oil palm and eucalyptus although it showed negligible effect on J. curcas. Our results suggest that strains belonging to the novel Burkholderia-related genera widely promote plant growth via both N-independent and N-dependent mechanisms. Our results also suggest that the induction of defense response may prevent the colonization of an endophyte in plants.

Download Full-text

Root-specific camalexin biosynthesis controls the plant growth-promoting effects of multiple bacterial strains

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1818604116 ◽

2019 ◽

Vol 116 (31) ◽

pp. 15735-15744 ◽

Cited By ~ 25

Author(s):

Anna Koprivova ◽

Stefan Schuck ◽

Richard P. Jacoby ◽

Irene Klinkhammer ◽

Bastian Welter ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Bacterial Strains ◽

Natural Ecosystems ◽

Promoting Effect ◽

Gene Encoding ◽

A Genome ◽

Sulfatase Activity ◽

Plant Growth Promoting ◽

Growth Promoting

Plants in their natural ecosystems interact with numerous microorganisms, but how they influence their microbiota is still elusive. We observed that sulfatase activity in soil, which can be used as a measure of rhizosphere microbial activity, is differently affected by Arabidopsis accessions. Following a genome-wide association analysis of the variation in sulfatase activity we identified a candidate gene encoding an uncharacterized cytochrome P450, CYP71A27. Loss of this gene resulted in 2 different and independent microbiota-specific phenotypes: A lower sulfatase activity in the rhizosphere and a loss of plant growth-promoting effect by Pseudomonas sp. CH267. On the other hand, tolerance to leaf pathogens was not affected, which agreed with prevalent expression of CYP71A27 in the root vasculature. The phenotypes of cyp71A27 mutant were similar to those of cyp71A12 and cyp71A13, known mutants in synthesis of camalexin, a sulfur-containing indolic defense compound. Indeed, the cyp71A27 mutant accumulated less camalexin in the roots upon elicitation with silver nitrate or flagellin. Importantly, addition of camalexin complemented both the sulfatase activity and the loss of plant growth promotion by Pseudomonas sp. CH267. Two alleles of CYP71A27 were identified among Arabidopsis accessions, differing by a substitution of Glu373 by Gln, which correlated with the ability to induce camalexin synthesis and to gain fresh weight in response to Pseudomonas sp. CH267. Thus, CYP71A27 is an additional component in the camalexin synthesis pathway, contributing specifically to the control of plant microbe interactions in the root.

Download Full-text

Isolation and Molecular Characterization of a Model Antagonistic Pseudomonas aeruginosa Divulging In Vitro Plant Growth Promoting Characteristics

BioMed Research International ◽

10.1155/2018/6147380 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 9

Author(s):

Bushra Uzair ◽

Rehana Kausar ◽

Syeda Asma Bano ◽

Sammer Fatima ◽

Malik Badshah ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Plant Growth ◽

Growth Promotion ◽

Gene Bank ◽

Accession Number ◽

Bacterial Strains ◽

Rhizopus Microsporus ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Gene Bank Accession

The use of microbial technologies in agriculture is currently expanding quite rapidly with the identification of new bacterial strains, which are more effective in promoting plant growth. In the present study 18 strains of Pseudomonas were isolated from soil sample of Balochistan coastline. Among isolated Pseudomonas strains four designated as SP19, SP22, PS24, and SP25 exhibited biocontrol activities against phytopathogenic fungi, that is, Rhizopus microsporus, Fusarium oxysporum, Aspergillus niger, Alternaria alternata, and Penicillium digitatum; PS24 identified as Pseudomonas aeruginosa by 16srRNA gene bank accession number EU081518 was selected on the basis of its antifungal activity to explore its potential as plant growth promotion. PS24 showed multiple plant growth promoting attributes such as phosphate solubilization activity, indole acetic acid (IAA), siderophore, and HCN production. In order to determine the basis for antifungal properties, antibiotics were extracted from King B broth of PS24 and analyzed by TLC. Pyrrolnitrin antibiotic was detected in the culture of strain PS24. PS24 exhibited antifungal activities found to be positive for hydrogen cyanide synthase Hcn BC gene. Sequencing of gene of Hcn BC gene of strain PS24 revealed 99% homology with the Pseudomonas aeruginosa strain PA01. The sequence of PS24 had been submitted in gene bank accession number KR605499. Ps. aeruginosa PS24 with its multifunctional biocontrol possessions can be used to bioprotect the crop plants from phytopathogens.

Download Full-text

The Pseudomonas Secondary Metabolite 2,4-Diacetylphloroglucinol Is a Signal Inducing Rhizoplane Expression of Azospirillum Genes Involved in Plant-Growth Promotion

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-07-10-0148 ◽

2011 ◽

Vol 24 (2) ◽

pp. 271-284 ◽

Cited By ~ 83

Author(s):

Emeline Combes-Meynet ◽

Joël F. Pothier ◽

Yvan Moënne-Loccoz ◽

Claire Prigent-Combaret

Keyword(s):

Plant Growth ◽

Secondary Metabolite ◽

Growth Promotion ◽

Plant Growth Promoting Rhizobacteria ◽

Fluorescence Induction ◽

Auxin Production ◽

Wide Range ◽

Enhanced Expression ◽

Plant Growth Promoting ◽

Negative Mutant

During evolution, plants have become associated with guilds of plant-growth-promoting rhizobacteria (PGPR), which raises the possibility that individual PGPR populations may have developed mechanisms to cointeract with one another on plant roots. We hypothesize that this has resulted in signaling phenomena between different types of PGPR colonizing the same roots. Here, the objective was to determine whether the Pseudomonas secondary metabolite 2,4-diacetylphloroglucinol (DAPG) can act as a signal on Azospirillum PGPR and enhance the phytostimulation effects of the latter. On roots, the DAPG-producing Pseudomonas fluorescens F113 strain but not its phl-negative mutant enhanced the phytostimulatory effect of Azospirillum brasilense Sp245-Rif on wheat. Accordingly, DAPG enhanced Sp245-Rif traits involved in root colonization (cell motility, biofilm formation, and poly-β-hydroxybutyrate production) and phytostimulation (auxin production). A differential fluorescence induction promoter-trapping approach based on flow cytometry was then used to identify Sp245-Rif genes upregulated by DAPG. DAPG enhanced expression of a wide range of Sp245-Rif genes, including genes involved in phytostimulation. Four of them (i.e., ppdC, flgE, nirK, and nifX-nifB) tended to be upregulated on roots in the presence of P. fluorescens F113 compared with its phl-negative mutant. Our results indicate that DAPG can act as a signal by which some beneficial pseudomonads may stimulate plant-beneficial activities of Azospirillum PGPR.

Download Full-text