Plant Growth Promotion Function of Bacillus sp. Strains Isolated from Salt-Pan Rhizosphere and Their Biocontrol Potential against Macrophomina phaseolina

In recent decades, intensive crop management has involved excessive use of pesticides or fertilizers, compromising environmental integrity and public health. Accordingly, there has been worldwide pressure to find an eco-friendly and safe strategy to ensure agricultural productivity. Among alternative approaches, Plant Growth-Promoting (PGP) rhizobacteria are receiving increasing attention as suitable biocontrol agents against agricultural pests. In the present study, 22 spore-forming bacteria were selected among a salt-pan rhizobacteria collection for their PGP traits and their antagonistic activity against the plant pathogen fungus Macrophomina phaseolina. Based on the higher antifungal activity, strain RHFS10, identified as Bacillus vallismortis, was further examined and cell-free supernatant assays, column purification, and tandem mass spectrometry were employed to purify and preliminarily identify the antifungal metabolites. Interestingly, the minimum inhibitory concentration assessed for the fractions active against M. phaseolina was 10 times lower and more stable than the one estimated for the commercial fungicide pentachloronitrobenzene. These results suggest the use of B. vallismortis strain RHFS10 as a potential plant growth-promoting rhizobacteria as an alternative to chemical pesticides to efficiently control the phytopathogenic fungus M. phaseolina.

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Growth Promotion Function of Bacillus sp. Strains Isolated From Salt-Pan Rhizosphere and Their Biocontrol Potential Against Macrophomina Phaseolina

10.20944/preprints202102.0241.v1 ◽

2021 ◽

Author(s):

Stefany Castaldi ◽

Claudia Petrillo ◽

Giuliana Donadio ◽

Fabrizio del Piaz ◽

Alessio Cimmino ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Macrophomina Phaseolina ◽

Phytopathogenic Fungus ◽

Agricultural Pests ◽

Pgp Traits ◽

Antifungal Metabolites ◽

Salt Pan ◽

Plant Growth Promoting ◽

Growth Promoting

In the last decades, intensive crop management has involved excessive use of pesticides or fertilizers, compromising environmental integrity and public health. Accordingly, there has been worldwide pressure to find an eco-friendly and safe strategy to ensure agricultural productivity. Recently, Plant Growth-Promoting (PGP) rhizobacteria are receiving increasing attention as suitable biocontrol agents against agricultural pests. In the present study, 22 spore-forming bacteria were selected among a salt-pan rhizobacteria collection for their PGP traits and their antagonistic activity against the plant pathogen fungus Macrophomina phaseolina. Based on the higher antifungal activity, strain RHFS10, identified as Bacillus vallismortis, was furtherly examined and cell-free supernatants assays, column purification, and tandem mass spectrometry employed to purify and preliminarily identify the antifungal metabolites. Interestingly, the minimum inhibitory concentration assessed for the fractions active against M. phaseolina, resulted 10 times lower and more stable than the one estimated for the commercial fungicide pentachloronitrobenzene. These results suggest the use of B. vallismortis strain RHFS10 as a potential Plant Growth Promoting Rhizobacteria to efficiently control phytopathogenic fungus M. phaseolina, in alternative to chemical pesticides.

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Screening of efficient rhizobacteria associated with cauliflower (Brassica oleraceavar. botrytis L.) for plant growth promoting traits

Journal of Applied and Natural Science ◽

10.31018/jans.v9i1.1166 ◽

2017 ◽

Vol 9 (1) ◽

pp. 167-172

Author(s):

Sonal Bhardwaj ◽

Bhawna Dipta ◽

Shruti Kirti ◽

Rajesh Kaushal

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Himachal Pradesh ◽

Pgp Traits ◽

Antifungal Metabolites ◽

Stalk Rot ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Phosphate Solubilizing

In the current study, a total of 25 isolates were isolated from the rhizosphere and roots of cauliflower (Brassica oleraceavar. botrytis L.) from the vicinity of Una district of Himachal Pradesh. The isolates were tested in vitro for their ability to solubilise phosphorous and produce siderophore, indole acetic acid (IAA), hydrogen cyanide (HCN) and antifungal metabolites against the soil borne pathogens. Results revealed that out of 25, only 4 rhizospheric isolates (SB5, SB11, SB8 and SB10) have maximum plant growth promoting attributes. The isolates were identified as Bacillus sp. on the basis of Bergey’s manual of systematic bacteriology. The isolate SB11 recorded highest phosphate solubilizing efficiency in solid medium (109.09%) and in liquid medium (350μg/ml). Maximum production of IAA (51.96μg/ml), siderophore (91.41%) and HCN were also observed for the same isolate. Further-more, the isolate SB11 produced highest antifungal metabolite production against Rhizoctoniasolani(37.11%), Sclerotiniasclerotiorum(41.11%), and Pythium sp. (71.11%) causing root rot, stalk rot and damping off diseases in cauliflower, respectively. The selected isolate (SB11) showed optimum growth at a pH of 7.0, 35°C temperature and 2% NaCl. On the basis of multifarious PGP-traits the SB11 isolate has tremendous potential to be used as a bioferti-lizer/bioprotectant for growth promotion and natural protection of cauliflower under low hill conditions of Himachal Pradesh.

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Plant growth promoting endophyte Burkholderia contaminans NZ antagonizes phytopathogen Macrophomina phaseolina through melanin synthesis and pyrrolnitrin inhibition

PLoS ONE ◽

10.1371/journal.pone.0257863 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0257863

Author(s):

Nazia R. Zaman ◽

Umar F. Chowdhury ◽

Rifath N. Reza ◽

Farhana T. Chowdhury ◽

Mrinmoy Sarker ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Genome Mining ◽

Gene Clusters ◽

Macrophomina Phaseolina ◽

Melanin Synthesis ◽

Burkholderia Contaminans ◽

Plant Growth Promoting ◽

Growth Promoting

The endophytic bacterium Burkholderia contaminans NZ was isolated from jute, which is an important fiber-producing plant. This bacterium exhibits significant growth promotion activity in in vivo pot experiments, and like other plant growth-promoting (PGP) bacteria fixes nitrogen, produces indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. B. contaminans NZ is considered to exert a promising growth inhibitory effect on Macrophomina phaseolina, a phytopathogen responsible for infecting hundreds of crops worldwide. This study aimed to identify the possibility of B. contaminans NZ as a safe biocontrol agent and assess its effectiveness in suppressing phytopathogenic fungi, especially M. phaseolina. Co-culture of M. phaseolina with B. contaminans NZ on both solid and liquid media revealed appreciable growth suppression of M. phaseolina and its chromogenic aberration in liquid culture. Genome mining of B. contaminans NZ using NaPDoS and antiSMASH revealed gene clusters that displayed 100% similarity for cytotoxic and antifungal substances, such as pyrrolnitrin. GC-MS analysis of B. contaminans NZ culture extracts revealed various bioactive compounds, including catechol; 9,10-dihydro-12’-hydroxy-2’-methyl-5’-(phenylmethyl)- ergotaman 3’,6’,18-trione; 2,3-dihydro-3,5- dihydroxy-6-methyl-4H-pyran-4-one; 1-(1,6-Dioxooctadecyl)- pyrrolidine; 9-Octadecenamide; and 2- methoxy- phenol. These compounds reportedly exhibit tyrosinase inhibitory, antifungal, and antibiotic activities. Using a more targeted approach, an RP-HPLC purified fraction was analyzed by LC-MS, confirming the existence of pyrrolnitrin in the B. contaminans NZ extract. Secondary metabolites, such as catechol and ergotaman, have been predicted to inhibit melanin synthesis in M. phaseolina. Thus, B. contaminans NZ appears to inhibit phytopathogens by apparently impairing melanin synthesis and other potential biochemical pathways, exhibiting considerable fungistatic activity.

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Bioprospecting desert plant Bacillus endophytic strains for their potential to enhance plant stress tolerance

Scientific Reports ◽

10.1038/s41598-019-54685-y ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 8

Author(s):

Ameerah Bokhari ◽

Magbubah Essack ◽

Feras F. Lafi ◽

Cristina Andres-Barrao ◽

Rewaa Jalal ◽

...

Keyword(s):

Salt Stress ◽

Plant Growth ◽

Growth Promotion ◽

Stress Conditions ◽

Desert Plant ◽

Plant Growth Promoting Bacteria ◽

Fresh Weight ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

AbstractPlant growth-promoting bacteria (PGPB) are known to increase plant tolerance to several abiotic stresses, specifically those from dry and salty environments. In this study, we examined the endophyte bacterial community of five plant species growing in the Thar desert of Pakistan. Among a total of 368 culturable isolates, 58 Bacillus strains were identified from which the 16 most divergent strains were characterized for salt and heat stress resilience as well as antimicrobial and plant growth-promoting (PGP) activities. When the 16 Bacillus strains were tested on the non-host plant Arabidopsis thaliana, B. cereus PK6-15, B. subtilis PK5-26 and B. circulans PK3-109 significantly enhanced plant growth under salt stress conditions, doubling fresh weight levels when compared to uninoculated plants. B. circulans PK3-15 and PK3-109 did not promote plant growth under normal conditions, but increased plant fresh weight by more than 50% when compared to uninoculated plants under salt stress conditions, suggesting that these salt tolerant Bacillus strains exhibit PGP traits only in the presence of salt. Our data indicate that the collection of 58 plant endophytic Bacillus strains represents an important genomic resource to decipher plant growth promotion at the molecular level.

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Endophytic Burkholderia sp. SSG as a potential biofertilizer promoting boxwood growth

PeerJ ◽

10.7717/peerj.9547 ◽

2020 ◽

Vol 8 ◽

pp. e9547

Author(s):

Ping Kong ◽

Chuanxue Hong

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Plant Protection ◽

Growth Promotion ◽

Agar Plate ◽

Gene Clusters ◽

Plant Weight ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

Background Burkholderia sp. SSG is a bacterial endophyte isolated from boxwood leaves showing a resistant response to infection by the boxwood blight pathogen Calonectria pseudonaviculata. SSG acted as a protective and curative biocontrol agent for boxwood blight and as a bio-sanitizer of disease inoculum in the field. Many gene clusters involved in antibiotic production and plant growth promotion (PGP) were found in the genome, giving this endophyte great application potential as a treatment for plant protection. However, the PGP features have not been documented. This study investigated the plant growth promotion activity of SSG in boxwood. Methods To determine whether SSG is a plant growth promoting bacterium, four PGP traits, auxin and siderophore production, nitrogen fixation and phosphate solubilization, were examined in the laboratory with colorimetric or agar plate assays. The plant growth promoting activity of SSG was tested on three boxwood varieties characterized by slow, intermediate and fast growth rates, namely Justin Brouwers, Buddy and Winter Gem, respectively. These plants were drenched with an SSG cell suspension or water and washed plant weight was compared before and after treatment to determine growth changes after 10 months. Results The SSG culture was sustainable on nitrogen free media, suggesting that SSG may fix atmospheric nitrogen. It was also a strong phosphate solubilizer and a potent siderophore and indole-3-acetic acid (IAA) producer. Significant growth promotion was observed on boxwood cultivars Justin Brouwers, Buddy and Winter Gem 10 months after plant roots were drenched with SSG cells. The growth rate of treated plants was 76.1, 58.3, and 37.3% higher than that of the control, respectively. The degree of growth promotion was significantly different among plant varieties, notably more pronounced with the slow and intermediate growers. This study demonstrates that the SSG bacterium has multiple PGP traits and is a prospective plant biofertilizer.

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In Vitro Evaluation and Genome Mining of Bacillus subtilis Strain RS10 Reveals Its Biocontrol and Plant Growth-Promoting Potential

Agriculture ◽

10.3390/agriculture11121273 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1273

Author(s):

Sajid Iqbal ◽

Nimat Ullah ◽

Hussnain Ahmed Janjua

Keyword(s):

Bacillus Subtilis ◽

Plant Growth ◽

Genome Analysis ◽

Growth Promotion ◽

Gene Clusters ◽

Subtilis Strain ◽

Antifungal Metabolites ◽

Plant Growth Promoting ◽

Growth Promoting

Recently, crop management has involved excessive use of chemical fertilizers and pesticides, compromising public health and environmental integrity. Rhizobacteria, which can enhance plant growth and protect plants from phytopathogen, are eco-friendly and have been attracting increasing attention. In the current study, Bacillus subtilis RS10 isolated from the rhizosphere region of Cynodon dactylon, inhibited the growth of indicator strains and exhibited in vitro plant growth-promoting traits. A whole-genome analysis identified numerous biosynthetic gene clusters encoding antibacterial and antifungal metabolites including bacillibactin, bogorol A, fengycin, bacteriocin, type III polyketides (PKs), and bacilysin. The plant growth-promoting conferring genes involved in nitrogen metabolism, phosphate solubilization, hydrogen sulfide, phytohormones, siderophore biosynthesis, chemotaxis and motility, plant root colonization, lytic enzymes, and biofilm formation were determined. Furthermore, genes associated with abiotic stresses such as high salinity and osmotic stress were identified. A comparative genome analysis indicated open pan-genome and the strain was identified as a novel sequence type (ST-176). In addition, several horizontal gene transfer events were found which putatively play a vital role in the evolution and new functionalities of a strain. In conclusion, the current study demonstrates the potential of RS10 antagonism against important pathogens and plant growth promotion, highlighting its application in sustainable agriculture.

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Biocontrol of Macrophomina phaseolina (Tassi) Goid causing charcoal rot disease in Lycopersicon esculentum L. by using multi species bacterial consortia

Environment Conservation Journal ◽

10.36953/ecj.2021.22351 ◽

2021 ◽

Vol 22 (3) ◽

pp. 441-449

Author(s):

Pradeep Kumar ◽

Sandeep Kumar ◽

R.C. Dubey

Keyword(s):

Lycopersicon Esculentum ◽

Plant Growth ◽

Growth Promotion ◽

Macrophomina Phaseolina ◽

Growth And Yield ◽

Pseudomonas Sp ◽

Bacillus Sp ◽

Bacterial Strains ◽

Plant Growth Promoting ◽

Growth Promoting

Plant growth-promoting bacterial strains (LEP1-LEP31) were isolated from rhizosphere of Lycopersicon esculentum L. (Tomato) and screened for their plant growth promoting (PGP) activities. On the basis of morphological, physiological, biochemical, carbon source utilization and molecular characterization, these strains were identified as Pseudomonas sp., Azotobacter sp. and Bacillus sp. For antagonistic activities all the strains were subject to the chitinase activities by the development of clear halo around the inoculated bacterial spots when loaded on chitin (0.2%) supplemented mediumBased on pot and field trial results of individual strains and consortium application, it may be concluded that all the three strains i.e. Pseudomonas sp. LEP17, Azotobacter sp. strain LEP21 and Bacillus sp. strain LEP25 showed plant growth promoting effects. The growth promotion provided by these strains was apparently related to improve shoot and root development, which resulted in better nutrient uptake capability and suppression of plant pathogen. All these three strains were superior in this regard because they provided the best and most consistent effects on growth and yield of L. esculentum. All these strains Pseudomonas sp. LEP17, Azotobacter sp. strain LEP21, Bacillus sp. strain LEP25 and their consortium seems to be suitable for use as a plant growth promoting and improvement of growth and yield

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Isolation of plant growth-promoting Pseudomonas sp. PPR8 from the rhizosphere of Phaseolus vulgaris L.

Archives of Biological Sciences ◽

10.2298/abs150701028k ◽

2016 ◽

Vol 68 (2) ◽

pp. 363-374 ◽

Cited By ~ 4

Author(s):

Pankaj Kumar ◽

Ramesh Dubey ◽

Dinesh Maheshwari ◽

Yong-Ha Park ◽

Vivek Bajpai

Keyword(s):

Phaseolus Vulgaris ◽

Plant Growth ◽

Growth Promotion ◽

Rrna Gene ◽

Sequencing Analysis ◽

Pseudomonas Sp ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

In vitro screening of plant growth-promoting (PGP) traits was carried out using eight Pseudomonas spp., PPR1 to PPR8, isolated from the rhizosphere of Phaseolus vulgaris growing on the Uttarakhand Himalayan range in India. All the isolates were fast growers, positive for catalase, oxidase and urease activities, and utilized lactose and some amino acids. All the isolates were indole acetic acid (IAA) positive, however PPR8 solubilized potassium and zinc along with various other types of inorganic (tricalcium, dicalcium and zinc phosphate) and organic (calcium phytate) phosphates, as well as producing siderophore and ACC deaminase. PPR8 also produced cyanogens, extracellular chitinase, ?-1,3-glucanase, ?-1,4-glucanase and oxalate oxidase. Based on the PGP traits of all isolates, PPR8 was found to be the most potent plant growth-promoting rhizobacteria (PGPR). Further, PPR8 was identified as Pseudomonas sp. PPR8, based on 16S rRNA gene sequencing analysis. Moreover, the PGP activities of PPR8 confirmed it to be a potent biocontrol agent, inhibiting the growth of various plant pathogenic fungi. This study reveals the potential of Pseudomonas sp. PPR8 to be used as a good bioinoculant for growth promotion of common bean and for the protection of important legume crops from various deleterious phytopathogens.

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Improved chromium tolerance of Medicago sativa by plant growth-promoting rhizobacteria (PGPR)

Journal of Genetic Engineering and Biotechnology ◽

10.1186/s43141-021-00254-8 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Nabil Tirry ◽

Aziza Kouchou ◽

Bouchra El Omari ◽

Mohamed Ferioun ◽

Naïma El Ghachtouli

Keyword(s):

Plant Growth ◽

Medicago Sativa ◽

Contaminated Soils ◽

Plant Biomass ◽

Growth Promotion ◽

Plant Growth Promoting Rhizobacteria ◽

Biochemical Tests ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

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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Characterization of Root-Endophytic Actinobacteria From Cactus (Opuntia Ficus-Indica) for Plant Growth Promoting Traits

10.21203/rs.3.rs-482515/v1 ◽

2021 ◽

Author(s):

V Govindasamy ◽

Priya George ◽

S V Ramesh ◽

P Sureshkumar ◽

Jagadish Rane ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Pgp Traits ◽

Seedling Length ◽

Plant Growth Promoting ◽

Uninoculated Control ◽

Growth Promoting ◽

Endophytic Actinobacteria

Abstract The present study is the first report of isolation and characterization of endophytic actinobacteria from cactus (Opuntia ficus-indica). A total of 179 morphologically distinct endophytic actinobacterial isolates were purified from the roots of two different genetic accessions of cactus. All these isolates were screened for their plant growth promotion traits namely growth on N-free medium, P-solubilization, siderophore production, ACC deaminase activity and IAA production. A majority of the endophytic actinobacterial isolates (85%) exhibited the potential for plant growth promotion under in vitro conditions. Ten among the isolates were selected based on their multi-PGP traits and were identified as Streptomyces sp. based on the 16S rRNA gene sequencing and phylogenetic analysis. Plant growth promoting potential of these selected endophytic Streptomyces was studied in wheat seedlings. All these selected isolates significantly enhanced the growth parameters like seedling length and rootlets number compared to the uninoculated control. The wheat seeds inoculated with Streptomyces tuirus VL-70-IX exhibited maximum number of rootlets (6.33) compared to uninoculated control (3.67). The inoculation of endophytic actinobacteria Streptomyces pseudogriseolus VL-70-XII caused maximum seedling length (20.53 cm) and root length (8.26 cm) while the inoculation of S. radiopugnans HV-VIII resulted in highest shoot length (12.33 cm). These endophytic actinobacteria isolated from the roots of cactus accessions showed potential PGP traits. This work lays foundation for characterization and selection of endophytic actinobacteria from the under-exploited, drought tolerant species such as cactus with potential cross-compatibility for the improvement of plant growth of field crops especially under abiotic stress conditions..

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