scholarly journals Sorghum Growth Promotion by Paraburkholderia tropica and Herbaspirillum frisingense: Putative Mechanisms Revealed by Genomics and Metagenomics

2020 ◽  
Vol 8 (5) ◽  
pp. 725 ◽  
Author(s):  
Eiko E. Kuramae ◽  
Stan Derksen ◽  
Thiago R. Schlemper ◽  
Maurício R. Dimitrov ◽  
Ohana Y. A. Costa ◽  
...  

Bacteria from the genera Paraburkholderia and Herbaspirillum can promote the growth of Sorghum bicolor, but the underlying mechanisms are not yet known. In a pot experiment, sorghum plants grown on sterilized substrate were inoculated with Paraburkholderia tropica strain IAC/BECa 135 and Herbaspirillum frisingense strain IAC/BECa 152 under phosphate-deficient conditions. These strains significantly increased Sorghum bicolor cultivar SRN-39 root and shoot biomass. Shotgun metagenomic analysis of the rhizosphere revealed successful colonization by both strains; however, the incidence of colonization was higher in plants inoculated with P. tropica strain IAC/BECa 135 than in those inoculated with H. frisingense strain IAC/BECa 152. Conversely, plants inoculated with H. frisingense strain IAC/BECa 152 showed the highest increase in biomass. Genomic analysis of the two inoculants implied a high degree of rhizosphere fitness of P. tropica strain IAC/BECa 135 through environmental signal processing, biofilm formation, and nutrient acquisition. Both genomes contained genes related to plant growth-promoting bacterial (PGPB) traits, including genes related to indole-3-acetate (IAA) synthesis, nitrogen fixation, nodulation, siderophore production, and phosphate solubilization, although the P. tropica strain IAC/BECa 135 genome contained a slightly more extensive repertoire. This study provides evidence that complementary mechanisms of growth promotion in Sorghum might occur, i.e., that P. tropica strain IAC/BECa 135 acts in the rhizosphere and increases the availability of nutrients, while H. frisingense strain IAC/BECa 152 influences plant hormone signaling. While the functional and taxonomic profiles of the rhizobiomes were similar in all treatments, significant differences in plant biomass were observed, indicating that the rhizobiome and the endophytic microbial community may play equally important roles in the complicated plant-microbial interplay underlying increased host plant growth.

1998 ◽  
Vol 44 (10) ◽  
pp. 980-988 ◽  
Author(s):  
Elizabeth Bent ◽  
Christopher P Chanway

To test the hypothesis that rhizobacteria naturally present in soils may interfere with the extent of root colonization and plant growth promotion by plant growth-promoting rhizobacteria (PGPR), we studied two lodgepole pine PGPR (Bacillus polymyxa strains L6 and Pw-2) when inoculated singly and when coinoculated with a non-PGPR competitor (Curtobacterium flaccumfaciens PF322). Bacillus polymyxa Pw-2 and Curtobacterium flaccumfaciens PF322 were consistently found as endophytes, while Bacillus polymyxa L6 was never found within the root interior. Strains Pw-2 and L6 differed in the rate and type of growth promotion. Strain Pw-2 increased root growth (branching and elongation) and shoot biomass accumulation 6 and 9 weeks, respectively, after inoculation, while strain L6 increased primary root elongation and root biomass accumulation after 12 weeks. Seedlings coinoculated with Pw-2 and PF322 had decreased shoot biomass and primary root lengths when compared with seedlings inoculated only with Pw-2. This effect was not linked to a decrease in the population size of Pw-2 in the rhizosphere or in the root interior of coinoculated treatments. In contrast, strain L6-mediated growth promotion was not impaired by coinoculation with PF322. Strain L6 did interfere to some degree with the growth-promoting capability of strain Pw-2. These results indicate that endophytic PGPR may be less adapted to microbial competition than external root-colonizing PGPR, and that the efficacy of endophytic PGPR may be reduced by the presence of other bacteria on external or internal root tissues.Key words: PGPR, endophytes, colonization, coinoculation, competition.


Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 989 ◽  
Author(s):  
Noshin Ilyas ◽  
Roomina Mazhar ◽  
Humaira Yasmin ◽  
Wajiha Khan ◽  
Sumera Iqbal ◽  
...  

Halo-tolerant plant growth-promoting rhizobacteria (PGPR) have the inherent potential to cope up with salinity. Thus, they can be used as an effective strategy in enhancing the productivity of saline agro-systems. In this study, a total of 50 isolates were screened from the rhizospheric soil of plants growing in the salt range of Pakistan. Out of these, four isolates were selected based on their salinity tolerance and plant growth promotion characters. These isolates (SR1. SR2, SR3, and SR4) were identified as Bacillus sp. (KF719179), Azospirillum brasilense (KJ194586), Azospirillum lipoferum (KJ434039), and Pseudomonas stutzeri (KJ685889) by 16S rDNA gene sequence analysis. In vitro, these strains, in alone and in a consortium, showed better production of compatible solute and phytohormones, including indole acetic acid (IAA), gibberellic acid (GA), cytokinin (CK), and abscisic acid (ABA), in culture conditions under salt stress. When tested for inoculation, the consortium of all four strains showed the best results in terms of improved plant biomass and relative water content. Consortium-inoculated wheat plants showed tolerance by reduced electrolyte leakage and increased production of chlorophyll a, b, and total chlorophyll, and osmolytes, including soluble sugar, proline, amino acids, and antioxidant enzymes (superoxide dismutase, catalase, peroxidase), upon exposure to salinity stress (150 mM NaCl). In conclusion, plant growth-promoting bacteria, isolated from salt-affected regions, have strong potential to mitigate the deleterious effects of salt stress in wheat crop, when inoculated. Therefore, this consortium can be used as potent inoculants for wheat crop under prevailing stress conditions.


2018 ◽  
Vol 84 (22) ◽  
Author(s):  
Viviane Cordovez ◽  
Sharella Schop ◽  
Kees Hordijk ◽  
Hervé Dupré de Boulois ◽  
Filip Coppens ◽  
...  

ABSTRACTVolatile compounds produced by plant-associated microorganisms represent a diverse resource to promote plant growth and health. Here, we investigated the effect of volatiles from root-associatedMicrobacteriumspecies on plant growth and development. Volatiles of eight strains induced significant increases in shoot and root biomass ofArabidopsisbut differed in their effects on root architecture.Microbacteriumstrain EC8 also enhanced root and shoot biomass of lettuce and tomato. Biomass increases were also observed for plants exposed only briefly to volatiles from EC8 prior to transplantation of the seedlings to soil. These results indicate that volatiles from EC8 can prime plants for growth promotion without direct and prolonged contact. We further showed that the induction of plant growth promotion is tissue specific; that is, exposure of roots to volatiles from EC8 led to an increase in plant biomass, whereas shoot exposure resulted in no or less growth promotion. Gas chromatography–quadrupole time of flight mass spectometry (GC–QTOF-MS) analysis revealed that EC8 produces a wide array of sulfur-containing compounds, as well as ketones. Bioassays with synthetic sulfur volatile compounds revealed that the plant growth response to dimethyl trisulfide was concentration-dependent, with a significant increase in shoot weight at 1 μM and negative effects on plant biomass at concentrations higher than 1 mM. Genome-wide transcriptome analysis of volatile-exposedArabidopsisseedlings showed upregulation of genes involved in assimilation and transport of sulfate and nitrate. Collectively, these results show that root-associatedMicrobacteriumprimes plants, via the roots, for growth promotion, most likely via modulation of sulfur and nitrogen metabolism.IMPORTANCEIn the past decade, various studies have described the effects of microbial volatiles on other (micro)organismsin vitro, but their broad-spectrum activityin vivoand the mechanisms underlying volatile-mediated plant growth promotion have not been addressed in detail. Here, we revealed that volatiles from root-associated bacteria of the genusMicrobacteriumcan enhance the growth of different plant species and can prime plants for growth promotion without direct and prolonged contact between the bacterium and the plant. Collectively, these results provide new opportunities for sustainable agriculture and horticulture by exposing roots of plants only briefly to a specific blend of microbial volatile compounds prior to transplantation of the seedlings to the greenhouse or field. This strategy has no need for large-scale introduction or root colonization and survival of the microbial inoculant.


2019 ◽  
Vol 8 (38) ◽  
Author(s):  
Patricia Vaz Jauri ◽  
Martín Beracochea ◽  
Belén Fernández ◽  
Federico Battistoni

Streptomyces spp. produce many and diverse bioactive metabolites. Plant growth-promoting (PGP) activity by Streptomyces spp. has been reported repeatedly; however, the mechanisms are largely unknown. We report the sequencing of the genome of a PGP endophytic Streptomyces sp. strain, which will contribute to the understanding of the underlying mechanisms for growth promotion.


2019 ◽  
Vol 7 (10) ◽  
pp. 382
Author(s):  
Ben Mefteh ◽  
Bouket ◽  
Daoud ◽  
Luptakova ◽  
Alenezi ◽  
...  

The phosphogypsum (PG) endogenous bacterial community and endophytic bacterial communities of four plants growing in phosphogypsum-contaminated sites, Suaeda fruticosa (SF), Suaeda mollis (SM), Mesembryanthmum nodiflorum (MN) and Arthrocnemum indicum (AI) were investigated by amplicon sequencing. Results highlight a more diverse community of phosphogypsum than plants associated endophytic communities. Additionally, the bacterial culturable communities of phosphogypsum and associated plant endophytes were isolated and their plant-growth promotion capabilities, bioremediation potential and stress tolerance studied. Most of plant endophytes were endowed with plant growth-promoting (PGP) activities and phosphogypsum communities and associated plants endophytes proved highly resistant to salt, metal and antibiotic stress. They also proved very active in bioremediation of phosphogypsum and other organic and inorganic environmental pollutants. Genome sequencing of five members of the phosphogypsum endogenous community showed that they belong to the recently described species Bacillus albus (BA). Genome mining of BA allowed the description of pollutant degradation and stress tolerance mechanisms. Prevalence of this tool box in the core, accessory and unique genome allowed to conclude that accessory and unique genomes are critical for the dynamics of strain acquisition of bioremediation abilities. Additionally, secondary metabolites (SM) active in bioremediation such as petrobactin have been characterized. Taken together, our results reveal hidden untapped valuable bacterial actors for waste remediation.


Author(s):  
Thanh Nguyen Chu ◽  
Tieng Van Nhut Pham ◽  
Le Van Bui ◽  
Minh Thi Thanh Hoang

The application of plant growth-promoting rhizobacteria (PGPR) is one of the most promising alternative approaches to improve plant growth under salt stress. Among PGPR, Pseudomonas is a bacterial genus that possesses a variety of mechanisms for plant-growth-promoting and induction of biotic as well as abiotic stress tolerance. In this study, we screened three potential strains and tested the growth promotion of peanut (Arachis hypogaea) under saline conditions. All three isolates (strains) showed in vitro plant growth promoting traits such as the production of indoleacetic acid (IAA), phosphate solubilization, and nitrogen fixation.  Moreover, the 3 isolates present gene encoding ACC deaminase, and an important enzyme can promote plant growth to ameliorate abiotic stresses. Peanut inoculated with the strain BT00P03 showed the increase in fresh shoot biomass in normal and saline stress conditions. Our results showed that the BT00P03 strain might be used as a biological agent for eco-friendly agricultural practices. This research is the first step to understand the microbe-plant interaction mechanism under stress and to apply these strains to agricultural practices in the future.


2022 ◽  
Vol 11 (1) ◽  
pp. e29611124799
Author(s):  
Cristiane Rodrigues Silva ◽  
Rafael Monção Miller ◽  
Bárbara Costa Pereira ◽  
Lílian Aveleda ◽  
Victor Augustus Marin

A genomic analysis of the potential application of a Serratia marcescens strain in the plant-growth promotion. We performed whole-genome sequencing of Serratia marcescens isolated from a Minas Frescal Cheese. The genomic repertoire revealed a bacterium of agricultural and biotechnological interest. In the plant-growth promotion traits, we highlight genes encoding proteins possibly responsible for the biosynthesis of phytohormone indole acetic acid, organic compounds that act in iron uptake, and the Phosphate solubilization system. Genes encoding for enzymes like the versatile L-asparaginase stimulates the development of seeds and grains and can benefit the food industry due to a mitigation effect on acrylamide and notably, has medical applications as a chemotherapeutic agent or is applicable by its antimicrobial and anti-inflammatory properties. Moreover, functional diversity of genes encoding for resistance to different metals and metabolism of xenobiotics genes can be found in this strain, reinforcing its biotechnological potential. The versatile enzymes that can be produced by S. marcescens benefit the food, pharmaceutical, textile, agronomic, and cosmetic industries. The relevant genetic systems of S. marcescens described here may be used to promote plant growth and health and improve the environment. To the best of our knowledge, this is the first genome sequence report on S. marcescens isolated from cheese, with potential application as promoting plant growth and providing a baseline for future genomic studies on the development of this species.


Author(s):  
Shweta Gupta ◽  
Rajesh Kaushal ◽  
Gaurav Sood ◽  
Bhawna Dipta ◽  
Shruti Kirti ◽  
...  

The present study was initiated with testing of fifteen previously isolated indigenous plant growth promoting rhizobacteria for drought tolerance. Among all, two best isolates Pseudomonas aeruginosa (JHA6) and Bacillus amyloliquefaciens (ROH14) were selected for in-vivo studies. A total of ten treatments comprising Plant growth promoting rhizobacteria (PGPR) (JHA6 and ROH14) inoculated plants held at 80%, 60% and 40% field capacity (FC) soil moisture level was laid down in Completely Randomized Design with three replications. Un-inoculated plants held at various stress levels and non-stressed conditions (100% FC) served as control. In general, both the bacteria could promote Capsicum growth in terms of increase in root and shoot biomass, height of plants, chlorophyll content as well as increase in nutrient content and uptake. Besides, the bacterial inoculated Capsicum plants could withstand water stress more efficiently as indicated by increases in leaf area, total soluble proteins and relative water content of treated water stressed plants in comparison to untreated stressed ones. Enhanced antioxidant responses were evident as elevated activities of enzymes such as superoxide dismutase, catalase and peroxidase was recorded. Therefore, the ability of Capsicum plants to tolerate water stress is enhanced by application of the isolated bacteria which also function as plant growth promoting rhizobacteria.


Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1410
Author(s):  
Kaylee A. South ◽  
Nathan P. Nordstedt ◽  
Michelle L. Jones

The production of greenhouse ornamentals relies on high fertilizer inputs to meet scheduling deadlines and quality standards, but overfertilization has negative environmental impacts. The goals of this study were to identify plant-growth-promoting rhizobacteria (PGPR) that can improve greenhouse ornamental crop performance with reduced fertilizer inputs, and to identify the best measurements of plant performance for assessing the beneficial impact of PGPR on ornamentals. A high-throughput greenhouse trial was used to identify 14 PGPR isolates that improved the flower/bud number and shoot dry weight of Petunia × hybrida ‘Picobella Blue’ grown under low fertility conditions in peat-based media. These 14 PGPR were then applied to petunias grown under low fertility conditions (25 mg L−1 N). PGPR-treated plants were compared to negative (untreated at 25 mg L−1 N) and positive (untreated at 50, 75, 100, and 150 mg L−1 N) controls. Multiple parameters were measured in the categories of flowering, vegetative growth, and vegetative quality to determine the best measurements to assess improvements in ornamental plant performance. Caballeronia zhejiangensis C7B12-treated plants performed better in almost all parameters and were comparable to untreated plants fertilized with 50 mg L−1 N. Genomic analysis identified genes that were potentially involved in plant growth promotion. Our study identified potential PGPR that can be used as biostimulants to produce high-quality greenhouse ornamentals with lower fertilizer inputs.


Author(s):  
Nabil Tirry ◽  
Aziza Kouchou ◽  
Bouchra El Omari ◽  
Mohamed Ferioun ◽  
Naïma El Ghachtouli

Abstract Background Soil pollution by heavy metals increases the bioavailability of metals like hexavalent chromium (Cr (VI)), subsequently limiting plant growth and reducing the efficiency of phytoremediation. Plant growth-promoting rhizobacteria (PGPR) have substantial potential to enhance plant growth as well as plant tolerance to metal stress. The aim of this research was to investigate Cr (VI) phytoremediation enhancement by PGPR. Results The results showed that the 27 rhizobacterial isolates studied were confirmed as Cr (VI)-resistant PGPR, by using classical biochemical tests (phosphate solubilization, nitrogen fixation, indole acetic acid, exopolysaccharides, hydrogen cyanide, siderophores, ammonia, cellulase, pectinase, and chitinase production) and showed variable levels of Cr (VI) resistance (300–600 mg/L). The best four selected Cr (VI)-resistant PGPR (NT15, NT19, NT20, and NT27) retained most of the PGP traits in the presence of 100–200 mg/L concentrations of Cr (VI). The inoculation of Medicago sativa with any of these four isolates improved the shoot and root dry weight. The NT27 isolate identified using 16S rDNA gene sequence analyses as a strain of Pseudomonas sp. was most effective in terms of plant growth promotion and stress level decrease. It increased shoot and root dry weights of M. sativa by 97.6 and 95.4%, respectively, in the presence of Cr (VI) when compared to non-inoculated control plants. It also greatly increased chlorophyll content and decreased the levels of stress markers, malondialdehyde, hydrogen peroxide, and proline. The results of the effect of Pseudomonas sp. on Cr content and bioaccumulation factor (BAF) of the shoots and roots of M. sativa plants showed the increase of plant biomass concomitantly with the increase of Cr root concentration in inoculated plants. This would lead to a higher potential of Cr (VI) phytostabilization. Conclusions This study demonstrates that the association M. sativa-Pseudomonas sp. may be an efficient biological system for the bioremediation of Cr (VI)-contaminated soils.


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