Plant Growth-promoting Agents Research Articles

The BIOHERBICIDAL ACTIVITY OF Pseudomonas SPP (PF-097) To SUPRESS THE ALLELOPATHIC STRESS OF Trianthema portulacastrum LEAF EXTRACT ON Vigna mungo

Vigna mungo L. (black gram) is a summer pulse crop endemic to Central Asia. It is one of Pakistan's top five premium food beans and a highly cost-effective crop. Allelochemicals in Trianthema portulacastrum leaf extract effect and inhibit black gram germination rate, seedling length, fresh and dry biomass of seedling from low to high concentrations. The research revealed that in vitro leaf extract of black pigweed decrease the mash bean leaf germination percentage (34% to 6%), seedling length (10cm to 3cm), fresh biomass of seedling (2.4g to 0.94g), dry biomass (1.2g to 0.47g). Biological tool Pseudomonas (PF- 097) act as bioherbicide and as plant growth promoter agent (PGPR) to decrease the Trianthema portulacastrum allelopathic stress and to enhance the growth of black gram. The Pseudomonas (PF-097) PGPR addition in vitro experiment increased mash bean leaf germination (8-42%), seedling length (12-54%), and fresh biomass of seedling (8-17%) and dry biomass of seedling (0.47g-1.2g). In vivo experimental study revealed that whole plant material of black pigweed significantly suppress the shoot length (46cm to 18cm), shoot fresh biomass (2.6g to 0.66g) and shoot dry biomass (1.31g to 0.33g) and Pseudomonas (PF-097) PGPR incorporation in vivo experminet significantly increased the shoot length (4% to 12%), shoot fresh biomass (18% to 35%), shoot dry biomass (17% to 35%). Physiological activity of Catalase and peroxidase considerably increased in negative treatments amended with only T. portulacastrum and decreased in positive treatments by using biological agent Pseudomonas spp (PF- 097). By the amendment of Pseudomonas (PF- 097) protein content of mash bean seedling was significantly increased in positive treatments as compared to negative treatments.

Low-cost production and application of lipopeptide for bioremediation and plant growth by Bacillus subtilis SNW3

At present time, every nation is absolutely concern about increasing agricultural production and bioremediation of petroleum-contaminated soil. Hence, with this intention in the current study potent natural surfactants characterized as lipopeptides were evaluated for low-cost production by Bacillus subtilis SNW3, previously isolated from the Fimkessar oil field, Chakwal Pakistan. The significant results were obtained by using substrates in combination (white beans powder (6% w/v) + waste frying oil (1.5% w/v) and (0.1% w/v) urea) with lipopeptides yield of about 1.17 g/L contributing 99% reduction in cost required for medium preparation. To the best of our knowledge, no single report is presently describing lipopeptide production by Bacillus subtilis using white beans powder as a culture medium. Additionally, produced lipopeptides display great physicochemical properties of surface tension reduction value (SFT = 28.8 mN/m), significant oil displacement activity (ODA = 4.9 cm), excessive emulsification ability (E24 = 69.8%), and attains critical micelle concentration (CMC) value at 0.58 mg/mL. Furthermore, biosurfactants produced exhibit excellent stability over an extensive range of pH (1–11), salinity (1–8%), temperature (20–121°C), and even after autoclaving. Subsequently, produced lipopeptides are proved suitable for bioremediation of crude oil (86%) and as potent plant growth-promoting agent that significantly (P < 0.05) increase seed germination and plant growth promotion of chili pepper, lettuce, tomato, and pea maximum at a concentration of (0.7 g/100 mL), showed as a potential agent for agriculture and bioremediation processes by lowering economic and environmental stress.Graphical

Antagonistic and plant growth promotion effects of Mucor moelleri, a potential biocontrol agent

With the increasing demand for high quality and environmentally safe or green food, Biological Control Agents (BCAs) are playing critical roles in green agriculture, which in turn has paved the way for the requirement of effective, appropriate microbial antagonists. In this study, Mucor moelleri AA1 was isolated and investigated for its growth promotion and antagonism against Athelia rolfsii and Colletotrichum gloeosporiodes. The results showed a high antagonistic activity of M. moelleri against A. rolfsii and C. gloeosporiodes with percentage inhibitions of 73 % and 86 % respectively using the dual plate method, and the same antagonistic activity was also observed in liquid cocultures. A pot study analysis showed significant suppression of the diseases as well as growth promotion on tomato. Scanning electron microscopy (SEM) indicated that M. moelleri inhibited the growth of mycelium and the production of web-like materials. Based on headspace-solid phase microextraction (HS-SPME) analysis, microbial volatile compounds were determined, which were mainly aromatic compounds and alkaloids. Also, several antagonistic enzymes, such as β-1, 3- glucanase, proteases, catalase and ACC deaminase as well as the phytohormone IAA, were found to be produced by M. moelleri. Overall, these results combine to make M. moelleri a good prospective candidate for biological control and as a plant growth-promoting agent. The present study appears to be the first report identifying M. moelleri as a biological control agent.

Phomopsis liquidambaris reduces ethylene biosynthesis in rice under salt stress via inhibiting the activity of 1-aminocyclopropane-1-carboxylate deaminase.

The endophytic fungus Phomopsis liquidambaris is characterized as a plant growth-promoting agent under salt stress, but its mechanism is unknown. Herein, 1-aminocyclopropane-1-carboxylatedeaminase (ACCD) from the strain was confirmed that it had the ability of utilizing1-aminocyclopropane-1-carboxylate as the sole nitrogen source. The full-length ACCD gene was 1152bp, which encodes a mature protein of 384 amino acids with a molecular mass of 41.53kDa. The ACCD activity was 3.9-fold in 3mmol L-1 ACC by qRT-PCR under salt stress comparing with no salt tress. Ethylene production was increased to 34.55-70.60% and reduced the growth of rice by 23-69.73% under salt stress. Inoculation of P. liquidambaris increased root-shoot length, fresh and dry weight, and overall growth of stressed rice seedlings. ACC accumulation, ACC synthase and ACC oxidase activities increased in salt-treated rice seedlings, while they were significantly reduced when P. liquidambaris was inoculated into rice by qRT-PCR. It therefore can be concluded that P. liquidambaris can be used as a plant growth promoting fungus against salt stress and other biotic or abiotic stresses.

Characterization of Streptomyces spp. from Rice Fields as a Potential Biocontrol Agent against Burkholderia glumae and Rice Plant Growth Promoter

The usage of plant growth-promoting (PGP) Streptomyces to improve plant growth is an alternative to existing strategies of chemical fertilizers that commonly caused environmental pollution. The aim of this study was to isolate and characterize PGP Streptomyces from Malaysian rice fields with antagonistic activity against Bacterial Panicle Blight disease in rice caused by Burkholderia glumae. A total of 50 bacterial isolates were recovered from the soil, rhizosphere, and endosphere; 22% showed antagonistic activity against B. glumae. Molecular identification using 16S rRNA amplification and phylogenetic tree analyses revealed that the antagonistic isolates belonged to the genus Streptomyces. Among the antagonistic isolates, Streptomyces sp. TBS5 (26.35 ± 0.14 mm) demonstrated the most antagonistic activity (p &lt; 0.05) against B. glumae. Through API® ZYM analysis, the antagonistic isolates were revealed to have phosphoric hydrolase, ester hydrolase, peptide hydrolase, and glycosidase activities that play a crucial role in plant growth promotion. The antagonistic isolates demonstrated the highest (80%) PGP traits including able to fix nitrogen and solubilize phosphate, as well as produce siderophore and indole-3-acetic acid. Plant growth promotion assay under laboratory and greenhouse conditions were analyzed with the treatment of rice, Oryza sativa, seeds with the antagonistic isolates. Seeds treated with Streptomyces sp. TBS5, JAS2, R2-7, and TKR8 showed improvement in vigor index by more than 100% compared to water-treated control plants under both conditions. Augmentation of root length showed an overall increment of more than 101.5% under laboratory condition and 151.9% under greenhouse condition using Streptomyces sp. TBS5, JAS2, R2-7, and TKR8 treatments. Results suggest that Streptomyces sp. TBS5, JAS2, R2-7, and TKR8 are a good candidate to be developed as both biocontrol agent against B. glumae and PGP agent in rice.

Growth Enhancement of Arabidopsis (Arabidopsis thaliana) and Onion (Allium cepa) With Inoculation of Three Newly Identified Mineral-Solubilizing Fungi in the Genus Aspergillus Section Nigri.

Some soil fungi play an important role in supplying elements to plants by the solubilizing of insoluble minerals in the soil. The present study was conducted to isolate the mineral-solubilizing fungi from rhizosphere soil in some agricultural areas in northern Thailand. Seven fungal strains were obtained and identified using a polyphasic taxonomic approach with multilocus phylogenetic and phenotypic (morphology and extrolite profile) analyses. All obtained fungal strains were newly identified in the genus Aspergillus section Nigri, Aspergillus chiangmaiensis (SDBR-CMUI4 and SDBR-CMU15), Aspergillus pseudopiperis (SDBR-CMUI1 and SDBR-CMUI7), and Aspergillus pseudotubingensis (SDBR-CMUO2, SDBR-CMUO8, and SDBR-CMU20). All fungal strains were able to solubilize the insoluble mineral form of calcium, copper, cobalt, iron, manganese, magnesium, zinc, phosphorus, feldspar, and kaolin in the agar plate assay. Consequently, the highest phosphate solubilization strains (SDBR-CMUI1, SDBR-CMUI4, and SDBR-CMUO2) of each fungal species were selected for evaluation of their plant growth enhancement ability on Arabidopsis and onion in laboratory and greenhouse experiments, respectively. Plant disease symptoms were not found in any treatment of fungal inoculation and control. All selected fungal strains significantly increased the leaf number, leaf length, dried biomass of shoot and root, chlorophyll content, and cellular inorganic phosphate content in both Arabidopsis and onion plants under supplementation with insoluble mineral phosphate. Additionally, the inoculation of selected fungal strains also improved the yield and quercetin content of onion bulb. Thus, the selected strains reveal the potential in plant growth promotion agents that can be applied as a biofertilizer in the future.

Identification and Differentiation of Pseudomonas Species in Field Samples Using an rpoD Amplicon Sequencing Methodology

ABSTRACTSpecies of the genus Pseudomonas are used for several biotechnological purposes, including plant biocontrol and bioremediation. To exploit the Pseudomonas genus in environmental, agricultural, or industrial settings, the organisms must be profiled at the species level as their bioactivity potential differs markedly between species. Standard 16S rRNA gene amplicon profiling does not allow for accurate species differentiation. Thus, the purpose of this study was to develop an amplicon-based high-resolution method targeting a 760-nucleotide (nt) region of the rpoD gene enabling taxonomic differentiation of Pseudomonas species in soil samples. The method was benchmarked on a 16-member Pseudomonas species mock community. All 16 species were correctly and semiquantitatively identified using rpoD gene amplicons, whereas 16S rRNA V3-V4 amplicon sequencing only correctly identified one species. We analyzed the Pseudomonas profiles in 13 soil samples in northern Zealand, Denmark, where samples were collected from grassland (3 samples) and agriculture soil (10 samples). Pseudomonas species represented up to 0.7% of the 16S rRNA gene abundance, of which each sampling site contained a unique Pseudomonas composition. Thirty culturable Pseudomonas strains were isolated from each grassland site and 10 from each agriculture site and identified by Sanger sequencing of the rpoD gene. In all cases, the rpoD amplicon approach identified more species than were found by cultivation, including hard-to-culture nonfluorescent pseudomonads, as well as more than were found by 16S rRNA V3-V4 amplicon sequencing. Thus, rpoD profiling can be used for species profiling of Pseudomonas, and large-scale prospecting of bioactive Pseudomonas may be guided by initial screening using this method.IMPORTANCE A high-throughput sequencing-based method for profiling of Pseudomonas species in soil microbiomes was developed and identified more species than 16S rRNA gene sequencing or cultivation. Pseudomonas species are used as biocontrol organisms and plant growth-promoting agents, and the method will allow tracing of specific species of Pseudomonas as well as enable screening of environmental samples for further isolation and exploitation.

Oxidative stress tolerance potential of milk thistle ecotypes after supplementation of different plant growth-promoting agents under salinity

The aim of the present work was to evaluate the effect of different plant growth promoters (PGPs) such as ascorbic acid (500 μM), thiourea (250 μM) and moringa leaf extract (3%) to mitigate salinity stress (120 mM NaCl) in four different milk thistle [Silybum marianum (L.) Gaertn.] ecotypes from Faisalabad (FSD), Gujranwala (GUJ), Kallar Kahar (KK), and Quetta (QTA) under field conditions for two years (2017–2018). In the present study, oxidative stress indicators such as malondialdehyde (MDA) and hydrogen peroxide (H2O2) and activities of different antioxidant enzymes and levels of non-enzymatic antioxidants were significantly differed among ecotypes, salinity, and PGPs. Supplementation with ascorbic acid and moringa leaf extract improved antioxidant defense machinery during the acclimation process against salinity, and milk thistle ecotypes represent their background of ecological zones and inherent tendency to face and confronting stress with improving antioxidant levels to a significant extent in varying ways. Ecotypic variations showed that QTA ecotype Followed by FSD, GUJ, and KK had more antioxidant capacity, with minimum reactive oxygen species production. Interestingly, the correlation data revealed that MDA and H2O2 had a positive correlation with each other and showed a negative correlation with all the enzymatic and non-enzymatic antioxidants.

Plant growth-promoting activity in bean plants of endophytic bacteria isolated from Echeveria laui

Echeveria laui (Crassulaceae) is commonly commercialized due to its drought-tolerance capacity and to its rosette-shaped aesthetics. Since endophytes associated with plants from a dry or arid environment have scarcely been analyzed as yet, current research comprises the isolation of leaf endophytic bacteria from E. laui (one five-year-old and one two-year-old plants) investigating plant growth-promoting endophytic bacteria which may solubilize phosphate, fix nitrogen, produce exopolysaccharides/IAA and antagonize phytopathogens. Isolation by the maceration methodology provided a colonization rate of 1.98 x109 CFU g-1 for the two-year-old plant and 1.14 x 1010 CFU g-1 for the five-year-old one. All 40 isolates evaluated showed in vitro plant growth-promoting agent’s abilities, with emphasis on EG04, ELG18, and ELP06. The capacity of the three best bacterial isolates were evaluated under greenhouse conditions in common and black bean (Phaseolus vulgaris L.) plants. Based on the sequencing of the 16S rRNA region and phylogenetic analysis, the three endophytes were identified as Pantoea sp. (ELG04 and ELG18) and Erwinia sp. (ELP06). Under greenhouse conditions, statistically significant differences were found among the plants treated with the three endophytes when compared to control plants for fresh and dry shoot, root biomass and length.

The first member of Exserohilum rostratum beneficial for promoting growth and yield of sunchoke (Helianthus tuberosus L.)

Helianthus tuberosus L. (sunchoke or Jerusalem artichoke) has been widely applied in food and industrial products. Due to its economical benefits, sunchoke has been of great interest in many areas. Therefore, the aims of this study were to isolate fungal endophytes from sunchoke and screen for their ability to produce IAA, GA3 and other plant growth-promoting (PGP) agents. Among a total of 126 isolates, 4 most effective PGP strains were identified as C. gloeosporioides CPS3/5, G. cingulate NMS1.4, E. rostratum NMS1.5 and Xylariaceae sp. KKL3. In the pot experiments, several plant growth parameters such as plant height, diameter of stem, SPAD chlorophyll content, plant biomass, plant root growth, the number of tubers and tuber inulin content in sunchoke inoculated with these fungal endophytes were significantly higher than those of the uninoculated controls. Outstandingly, E. rostratum NMS1.5 exhibited the best performance on promoting growth and yield of sunchoke. Interestingly, strain NMS1.5 is the first member of E. rostratum that is beneficial to plant growth without causing any negative effects. This study suggested that our fungal endophytes can be effective plant growth promoters for use as biofertilizers for sunchoke production.

Novel marine yeast strains as plant growth-promoting agents improve defense in wheat (Triticum aestivum) against Fusarium oxysporum

Yeasts are multilateral opportunistic plant symbionts that can cause intrinsic changes in the metabolism of host plants, thereby increasing plant growth and activating plant defense against various diseases. Although yeasts isolated from soil and plants have been evaluated as biological control agents, the search for new antagonists continues. Marine yeasts can be an option for the selection of new plant promoters and antagonistic agents. The objective of the present study was selected to demonstrate the potential of two marine yeast strains isolated from Red Sea water to award beneficial agronomic quality to promote wheat growth and induce defense mechanism against Fusarium oxysporum and its ability to produce zearalenone. These yeast strains were identified based on the genotypic identification as Candida orthopsilosis and Rhodotorula mucilaginosa, and their sequences were deposited in the GenBank database under the accession number MN784461 and MN784463, respectively. The results of in vitro assay showed great inhibition on mycelial growth and zearalenone production level. Also, wheat seeds primed with the two yeast strains in the presence and absence of Fusarium displayed early seedling emergence and enhanced growth compared with wheat treated by Fusarium only and untreated wheat (control). Also, under greenhouse conditions, C. orthopsilosis and R. mucilaginosa revealed remarkable improvement in the wheat growth parameters and resistance against Fusarium oxysporum and led to a complete inhibition of zearalenone production in treated wheat roots and spikes compared to those treated by Fusarium only. Our findings demonstrated the contribution of tested marine yeasts in the increase in metabolites accumulation.

Induction of Systemic Resistance against Bacterial Leaf Streak Disease and Growth Promotion in Rice Plant by Streptomyces shenzhenesis TKSC3 and Streptomyces sp. SS8.

The genus Streptomyces demonstrates enormous promise in promoting plant growth and protecting plants against various pathogens. Single and consortium treatments of two selected Streptomyces strains (Streptomyces shenzhenensis TKSC3 and Streptomyces sp. SS8) were evaluated for their growth-promoting potential on rice, and biocontrol efficiency through induced systemic resistance (ISR) mediation against Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of rice bacterial leaf streak (BLS) disease. Seed bacterization by Streptomyces strains improved seed germination and vigor, relative to the untreated seed. Under greenhouse conditions, seed bacterization with consortium treatment TKSC3 + SS8 increased seed germination, root length, and dry weight by 20%, 23%, and 33%, respectively. Single and consortium Streptomyces treatments also successfully suppressed Xoc infection. The result was consistent with defense-related enzyme quantification wherein single and consortium Streptomyces treatments increased peroxidase (POX), polyphenol oxidase, phenylalanine ammonia-lyase, and β,1–3 glucanase (GLU) accumulation compared to untreated plant. Within all Streptomyces treatments, consortium treatment TKSC3 + SS8 showed the highest disease suppression efficiency (81.02%) and the lowest area under the disease progress curve value (95.79), making it the best to control BLS disease. Consortium treatment TKSC3 + SS8 induced the highest POX and GLU enzyme activities at 114.32 μmol/min/mg protein and 260.32 abs/min/mg protein, respectively, with both enzymes responsible for plant cell wall reinforcement and resistant interaction. Our results revealed that in addition to promoting plant growth, these Streptomyces strains also mediated ISR in rice plants, thereby, ensuring protection from BLS disease.

Pseudomonas fluorescens F113 type VI secretion systems mediate bacterial killing and adaption to the rhizosphere microbiome

The genome of Pseudomonas fluorescens F113, a model rhizobacterium and a plant growth-promoting agent, encodes three putative type VI secretion systems (T6SSs); F1-, F2- and F3-T6SS. Bioinformatic analysis of the F113 T6SSs has revealed that they belong to group 3, group 1.1, and group 4a, respectively, similar to those previously described in Pseudomonas aeruginosa. In addition, in silico analyses allowed us to identify genes encoding a total of five orphan VgrG proteins and eight putative effectors (Tfe), some with their cognate immunity protein (Tfi) pairs. Genes encoding Tfe and Tfi are found in the proximity of P. fluorescens F113 vgrG, hcp, eagR and tap genes. RNA-Seq analyses in liquid culture and rhizosphere have revealed that F1- and F3-T6SS are expressed under all conditions, indicating that they are active systems, while F2-T6SS did not show any relevant expression under the tested conditions. The analysis of structural mutants in the three T6SSs has shown that the active F1- and F3-T6SSs are involved in interbacterial killing while F2 is not active in these conditions and its role is still unknown.. A rhizosphere colonization analysis of the double mutant affected in the F1- and F3-T6SS clusters showed that the double mutant was severely impaired in persistence in the rhizosphere microbiome, revealing the importance of these two systems for rhizosphere adaption.

Pantoea brenneri AS3 and Bacillus ginsengihumi M2.11 as Potential Biocontrol and Plant Growth-Promoting Agents

The mechanisms of biocontrol action of the strains Pantoea brenneri AS3 and Bacillus ginsengihumi M2.11 were investigated. The ability of the strains to release ammonium and cyanide ions was established, as well as their cellulase and protease activity and ability to fix nitrogen and to mobilize soil phosphates and phytates. The strains were able to synthesize siderophores, with their maximum production observed 48 h of cultivation reaching 198 ± 8 μM in B. ginsengihumi strain M2.11 and 84 ± 7 μM in P. brenneri strain AS3. The bacteria produced a phytohormone, indoleacetic acid (IAA), with the yields of 34 ± 3 and and 29 ± 2 μg/mL for B. ginsengihumi M2.11 and P. brenneri AS3, respectively, after 24 h of growth. It was found that both strains had fungicidal activity against plant pathogens of the genus Fusarium the growth of different Fusarium species was inhibited by more than 90% in the presence of P. brenneri AS3 or B. ginsengihumi M2.11. It was concluded that the strains P. brenneri AS3 and B. ginsengihumi M2.11, which possess multiple characteristics useful to plants, may be used as objects for creating biofertilizers and plant growth stimulators.

Distinctive Application of the Consortium of Chlorella vulgaris and Anabaena oryzae Toward Different Planting Dates and Climate Change on Jerusalem Artichoke Yield

Algae are considered as one of the plant growth promoters and have the potential to mitigate stress due to pesticide, salt and climate change. Two field trials of cultivation of Jerusalem artichoke were carried out in spring seasons 2018 and 2019 to select the convenient growing season for possible higher production of inulin content of Jerusalem artichoke tubers in Egypt and assessment of the real impact of bio-application with consortium of Chlorella vulgaris and Anabaena oryzae as a promising source of biologically secure and plant growth-promoting agents. Planting dates in, April 2018 and 2019 were found affecting significantly the harvest index and crop components. Results confirmed that seasonal variations had highly significant (p ≤ 0.05) effects on vegetative parameters, protein content, total carbohydrates, extracted inulin, antioxidant activity, phenolic compound content, and biomass productivity. High air temperature and humidity stress significantly inhibited biomass productivity in May and June during both seasons. The maximum harvest index was (0.541) being higher in April than in May or June. High-Performance Liquid Chromatography analysis showed the accumulation of inulin in Jerusalem artichoke (85%) in dry tubers. Fourier-Transform Infrared analysis showed the functional groups in the structure of extracted sugar from tubers. This is the first report of the consortium of algae as plant growth regulators to adapt J. artichoke crop, also this natural system of algae of the consortium to J. artichoke not only affects their growth, products but also soil management in the various agro-environmental areas of the world.

Field demonstration of irradiated sodium alginate as tea production booster

Sodium alginate oligomers were tested for tea plant growth promoter and anti-fungal agent in this experiment. Sodium alginate solutions were irradiated by Co-60 gamma radiation with different radiation doses to produce the oligomers. Irradiated solutions were then diluted into 150, 300 and 500 ppm prior to foliar application. Solutions were applied through foliar spraying at 7 days interval and the best response of tea plants in terms of various attributes were recorded. Tea buds were collected in 10 days of interval and the growth attributes like- total number of buds, fresh weight of buds, average leaf area and weight per bud, weight of made tea etc. were calculated. The experiment was continued up to 12 weeks and the attributes were averaged to get results per plucking. 12 kGy radiation doses along with 300ppm solution showed the best results and about 36% increase in productivity was found based on the fresh weight of buds. Total fungal count in tea leaves was also found to be reduced greatly. Based on the present study, irradiated sodium alginate could be used as safe and environmentally friendly agent to increase tea production.

Efficacy of plant growth-promoting bacteria Streptomyces werraensis F3 for chemical modifications of diseased soil of ginseng

ABSTRACT Rust rot and root rot of ginseng are common soil-borne diseases with an annual incidence of 20–50%. Here, a strain of Streptomyces werraensis, F3, isolated from ginseng rhizosphere was evaluated for its antifungal activity against ginseng root rot and rust rot-causing pathogens and for its growth-promoting properties. To further assess the potential agricultural use of F3, a pot experiment was performed using ginseng. The results showed that the inhibition rates of F3 bacterial suspension against the mycelial growth of rust rot and root rot pathogens in ginseng were 66.7% and 65.5%, respectively. Compared with the negative control, the germination concise vigour index of ginseng seed increased by 7.25 units upon treatment of the ginseng soil with F3, which could secrete indoleacetic acid and effectively promote the germination of ginseng. The pot experiment proved that F3, when applied as a biological control bacterial agent, improved the pH, organic matter, rapidly available nitrogen, available phosphorus, and available potassium, and the microbial community structure of the soil exposed to the disease for varying time periods. S. werraensis F3 has great potential to be commercialised as a biological control agents and a plant growth-promoting agent to effectively manage ginseng rust rot and root rot diseases.

Gene Knockout of Beneficial Plant-associated Bacillus spp. Using the CRISPR-Cas9 Double Plasmid System.

Bacillus spp. have great agricultural potential as a plant growth promoter and biocontrol agent. However, little is known concerning the bacterial molecular basis for the improvement of plant fitness. Thus, it is highly desirable to develop techniques that can contribute to the elucidation of the genetic basis for the mechanisms involved in beneficial bacterium-plant interactions. In this context, CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 is a powerful tool based on programmable molecular scissors that perform precise incisions in any DNA sequence. CRISPR-Cas9 can alter gene sequences and constitutes a cutting-edge tool to elucidate the role and function of bacterial genes associated with the benefits of plant interactions. The method described here uses a feasible CRISPR-Cas9 system in a double plasmid, one plasmid harboring the Cas9 endonuclease and the other the sgRNA, to promote gene knockout/editing in the Bacillus genus. This approach favors high efficiency in generating mutants for one or more genes in continuous or multiplex editing. Additionally, due to its universality, it can be applied to genera other than Bacillus.

Draft Genome Sequence of Collimonas pratensis Strain PMB3(1), an Effective Mineral-Weathering and Chitin-Hydrolyzing Bacterial Strain

We announce the draft genome sequence of Collimonas pratensis PMB3(1), isolated from the Scleroderma citrinum mycorrhizosphere. In addition to its mineral-weathering effectiveness and antifungal activity, this strain is characterized by genomic features that give it great potential as a biocontrol and plant growth-promoting agent in nutrient-poor soils.

A novel streptomyces rhizobacteria from desert soil with diverse anti-fungal properties

The Baja California desert harsher environment harbors a limited biodiversity due to extreme conditions like low moisture of sandy soils and high soil temperature. In the present study, actinobacteria from soil of Baja California desert was isolated and their properties as plant growth promoter and antifungal activity were evaluated. Streptomyces netropsis strain A-ICA was isolated and identified based on 16 S rDNA sequences from rhizosphere of native plant Larrea tridentata. The cell suspension and the cell-free supernatant of its culture showed significant antifungal activity against Macrophomina phaseolina, Fusarium oxysporum, Fusarium solani, Fusarium equiseti, Botrytis cinerea, Alternaria alternata and Colletotrichum gloeosporioides. Additionally, the results showed the potential of this strain for production of phytohormones (indol acetic acid and giberrelins) and exhibited highest concentration of soluble-P with the biggest drop in pH. Overall, the results of this study indicate that potential of S. netropsis strain A-ICA isolated from Baja California desert as a significant plant growth promoter and biocontrol agent to reduce growth of phytopathogens.