Biochemical and Molecular Characterization, and Bioprospecting of Drought Tolerant Actinomycetes from Maize Rhizosphere Soil

AbstractDrought is a major limitation to maize cultivation around the globe. Seven actinomycetes strains were isolated from maize rhizosphere soils in Mahikeng, North-West Province, South Africa. The isolates were biochemically characterized and identified with 16S rRNA gene sequence analysis. Isolates were also screened in vitro for abiotic stress tolerance to different concentrations of NaCl, pH, and polyethylene glycol (PEG 8000), as well as for biosynthesis of drought tolerance genes namely Glutathione peroxidase (GPX), Glycine-rich RNA binding protein (GRP), Desiccation protectant protein (DSP), Guanosine triphosphate binding protein (GTP) and plant growth-promoting genes:1-aminocyclopropane-1-carboxylate deaminase (accd) and siderophore biosynthesis (Sid). About 71.43% of isolates were of the genus Streptomyces (99-100% similarity), while 14.29% belong to the genus Arthrobacter (R15) and 14.29% to the genus Microbacterium (S11) respectively (99% similarity). Five isolates had their optimum growth at 35°C. Arthrobacter arilaitensis (R15) grew and tolerated 5%, 10%, and 20% PEG at 120 h. Root length increased by 110.53% in PEG treated maize seeds (−0.30 MPa) inoculated with Streptomyces pseudovenezuelae (S20) compared to the un-inoculated control. Likewise, germination percentage and vigor index increased by 37.53% and 194.81% respectively in PEG treated seeds inoculated with S20 than the un-inoculated PEG treated seeds. ACC deaminase gene was amplified in all the isolates, while the gene for siderophore biosynthesis was amplified in 85.71% of the isolates. Genes for the synthesis of GPX, GRP, DSP and GTP were amplified in Arthrobacter arilaitensis (R15) and Streptomyces pseudovenezuelae (S20) which lacked GTP. The amplification of drought-tolerant and plant growth-promoting primers indicates the possible presence of these genes in the isolates. These isolates have the potential for use as bio-inoculants, not only to improve drought tolerance in maize but also to be utilized as biofertilizers and biocontrol agents to facilitate growth promotion.

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Drought-tolerant plant growth-promoting rhizobacteria isolated from jujube (Ziziphus jujuba) and their potential to enhance drought tolerance

Plant and Soil ◽

10.1007/s11104-020-04582-5 ◽

2020 ◽

Vol 452 (1-2) ◽

pp. 423-440 ◽

Cited By ~ 3

Author(s):

Min Zhang ◽

Lin Yang ◽

Ruqian Hao ◽

Xiaoxiong Bai ◽

Ying Wang ◽

...

Keyword(s):

Drought Tolerance ◽

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Drought Tolerant ◽

Tolerant Plant ◽

Plant Growth Promoting ◽

Ziziphus Jujuba ◽

Growth Promoting

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Rhizobacteria Associated with Spilanthes acmella Murr. Confer Drought-Tolerance and Plant Growth Promotion

Biointerface Research in Applied Chemistry ◽

10.33263/briac115.1315513170 ◽

2021 ◽

Vol 11 (5) ◽

pp. 13155-13170

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Plant Growth ◽

Environmental Conditions ◽

Culturable Bacteria ◽

Drought Tolerant ◽

Plant Growth Promoting ◽

Spilanthes Acmella ◽

Growth Promoting ◽

Adverse Environmental Conditions

Plant growth-promoting rhizobacteria (PGPR) exhibit biocontrol and biofertilzer traits and help plants survive adverse environmental conditions. In this study, the rhizobacteria are explored for their ability to tolerate drought stress and their potential to act as plant growth promoters. Herein, we have isolated bacterial strains from the rhizosphere of Spilanthes acmella Murr. (toothache plant) found in the Shivalik hills region of Himachal Pradesh. We screened nine drought-tolerant culturable bacteria by analyzing their ability to survive in varying concentrations of polyethylene glycol (PEG) (10% - 50%), which is further supported by their 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and their ability to release exopolysaccharides (EPS). Strains having these activities are identified by 16S rDNA analysis, which reveals that they belong to four different bacteria genera, namely Klebsiella, Enterobacter, Burkholderia, and Pantoea. These isolates also harbor plant growth-promoting traits such as solubilization of phosphate, production of indole-3-acetic acid (IAA), siderophore, ammonia, hydrogen cyanide (HCN), and antifungal activity. The Enterobacter cloacae showed maximum drought tolerance among all the other isolates. We found that the drought stress of 60% PEG inhibited wheat seedlings' growth, but the bacterization with the isolated strains stimulated seedling growth. Hence we conclude that these drought-tolerant PGPR from the rhizosphere of S. acmella Murr. can be utilized to enhance the survival and growth of plants under drought stress. The isolated strains not only exhibit the drought-tolerant ability but also show the biocontrol and biofertilizer traits. Inoculation of these strains could help the plant survive under adverse environmental conditions.

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A prospectus of plant growth promoting endophytic bacterium from orchid (Vanda cristata)

BMC Biotechnology ◽

10.1186/s12896-021-00676-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Sujit Shah ◽

Krishna Chand ◽

Bhagwan Rekadwad ◽

Yogesh S. Shouche ◽

Jyotsna Sharma ◽

...

Keyword(s):

Plant Growth ◽

Root Colonization ◽

Endophytic Bacterium ◽

Epifluorescence Microscopy ◽

In Vitro Cultivation ◽

Rrna Gene ◽

Bacillus Spp ◽

Plant Growth Promoting ◽

Growth Promoting

Abstract Background A plant growth-promoting endophytic bacterium PVL1 isolated from the leaf of Vanda cristata has the ability to colonize with roots of plants and protect the plant. PVL1 was isolated using laboratory synthetic media. 16S rRNA gene sequencing method has been employed for identification before and after root colonization ability. Results Original isolated and remunerated strain from colonized roots were identified as Bacillus spp. as per EzBiocloud database. The presence of bacteria in the root section of the plantlet was confirmed through Epifluorescence microscopy of colonized roots. The in-vitro plantlet colonized by PVL1 as well as DLMB attained higher growth than the control. PVL1 capable of producing plant beneficial phytohormone under in vitro cultivation. HPLC and GC-MS analysis suggest that colonized plants contain Indole Acetic Acid (IAA). The methanol extract of Bacillus spp., contains 0.015 μg in 1 μl concentration of IAA. PVL1 has the ability to produce antimicrobial compounds such as ethyl iso-allocholate, which exhibits immune restoring property. One-way ANOVA shows that results were statistically significant at P ≤ 0.05 level. Conclusions Hence, it has been concluded that Bacillus spp. PVL1 can promote plant growth through secretion of IAA during root colonization and ethyl iso-allocholate to protect plants from foreign infections. Thus, this study supports to support Koch’s postulates of bacteria establishment.

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Assessing the Plant Growth-promoting Traits and Host Specificity of Endophytic Bacteria of Pulse Crops

Legume Research - An International Journal ◽

10.18805/lr-4491 ◽

2021 ◽

Author(s):

R. Thamizh Vendan ◽

D. Balachandar

Keyword(s):

Plant Growth ◽

Endophytic Bacteria ◽

Gene Sequencing ◽

16S Rrna Gene Sequencing ◽

Growth And Yield ◽

Rrna Gene ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Rrna Gene Sequencing ◽

Plant Growth Promoting Traits

Background: Symbiotic associations between legumes and Rhizobia are ancient and fundamental. However, the plant growth-promoting endophytes other than Rhizobia are not yet fully explored for pulses productivity. The present study was aimed to isolate efficient endophytic bacteria from pulses, assess their diversity, screen their plant growth-promoting activities and to test their potential as bio inoculants for pulses.Methods: We have isolated several endophytic bacteria from pulse crops more specifically from blackgram (Vigna mungo) and greengram (Vigna radiata). After careful screening, 15 promising endophytic isolates were selected for this study. The identification of endophytic bacterial isolates was performed by 16S rRNA gene sequencing. The isolates were tested for their potential for the plant growth-promoting traits such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production, siderophore secretion and antifungal activity. Pot culture experiments were conducted with the screened potential endophytic cultures.Result: The 16S rRNA gene sequencing revealed that species of Enterobacter, Bacillus, Pantoea, Pseudomonas, Acromobacter, Ocrobacterium were found as endophytes in blackgram and greengram. The in vitro screening identified Bacillus pumilus (BG-E6), Pseudomonas fluorescens (BG-E5) and Bacillus licheniformis (BG-E3) from blackgram and Pseudomonas chlororaphis (GG-E2) and Bacillus thuringiensis (GG-E7) from greengram as potential plant growth-promoting endophytes. These strains showed antagonism against plant pathogenic fungi. Upon inoculation of these endophytic PGPR strains, the blackgram and greengram growth and yield got increased. Among the strains, BG-E6 recorded 14.7% increased yield in blackgram and GG-E2 accounted for a 19.5% yield increase in greengram compared to respective uninoculated control. The experimental results showed that there was a host specificity found among the endophytic bacterial cultures with pulses. The cross inoculation of endophytic strains did not perform well to enhance the growth and yield of their alternate hosts.

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Draft Genome Sequence of Plant Growth-Promoting Drought-Tolerant Bacillus sp. Strain CMAA 1363 Isolated from the Brazilian Caatinga Biome

Genome Announcements ◽

10.1128/genomea.01534-16 ◽

2017 ◽

Vol 5 (5) ◽

Cited By ~ 1

Author(s):

Vanessa Nessner Kavamura ◽

Suikinai Nobre Santos ◽

Rodrigo Gouvêa Taketani ◽

Rafael Leandro Figueiredo Vasconcellos ◽

Itamar Soares Melo

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Draft Genome ◽

Negative Effects ◽

Genomic Features ◽

Drought Tolerant ◽

Caatinga Biome ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Plant Growth Promoting Traits

ABSTRACT The strain of Bacillus sp. CMAA 1363 was isolated from the Brazilian Caatinga biome and showed plant growth-promoting traits and ability to promote maize growth under drought stress. Sequencing revealed genes involved in stress response and plant growth promotion. These genomic features might aid in the protection of plants against the negative effects imposed by drought.

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Enhancement of drought tolerance in diverse Vicia faba cultivars by inoculation with plant growth-promoting rhizobacteria under newly reclaimed soil conditions

Scientific Reports ◽

10.1038/s41598-021-02847-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Elsayed Mansour ◽

Hany A. M. Mahgoub ◽

Samir A. Mahgoub ◽

El-Sayed E. A. El-Sobky ◽

Mohamed I. Abdul-Hamid ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Severe Drought ◽

Drought Conditions ◽

Moderate Drought ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Effects Of Drought

AbstractWater deficit has devastating impacts on legume production, particularly with the current abrupt climate changes in arid environments. The application of plant growth-promoting rhizobacteria (PGPR) is an effective approach for producing natural nitrogen and attenuating the detrimental effects of drought stress. This study investigated the influence of inoculation with the PGPR Rhizobium leguminosarum biovar viciae (USDA 2435) and Pseudomonas putida (RA MTCC5279) solely or in combination on the physio-biochemical and agronomic traits of five diverse Vicia faba cultivars under well-watered (100% crop evapotranspiration [ETc]), moderate drought (75% ETc), and severe drought (50% ETc) conditions in newly reclaimed poor-fertility sandy soil. Drought stress substantially reduced the expression of photosynthetic pigments and water relation parameters. In contrast, antioxidant enzyme activities and osmoprotectants were considerably increased in plants under drought stress compared with those in well-watered plants. These adverse effects of drought stress reduced crop water productivity (CWP) and seed yield‐related traits. However, the application of PGPR, particularly a consortium of both strains, improved these parameters and increased seed yield and CWP. The evaluated cultivars displayed varied tolerance to drought stress: Giza-843 and Giza-716 had the highest tolerance under well-watered and moderate drought conditions, whereas Giza-843 and Sakha-4 were more tolerant under severe drought conditions. Thus, co-inoculation of drought-tolerant cultivars with R. leguminosarum and P. putida enhanced their tolerance and increased their yield and CWP under water-deficit stress conditions. This study showed for the first time that the combined use of R. leguminosarum and P. putida is a promising and ecofriendly strategy for increasing drought tolerance in legume crops.

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Effect of Pyroligneous Acid on the Microbial Community Composition and Plant Growth-Promoting Bacteria (PGPB) in Soils

Soil Systems ◽

10.3390/soilsystems6010010 ◽

2022 ◽

Vol 6 (1) ◽

pp. 10

Author(s):

Anithadevi Kenday Sivaram ◽

Logeshwaran Panneerselvan ◽

Kannappar Mukunthan ◽

Mallavarapu Megharaj

Keyword(s):

Microbial Community ◽

Plant Growth ◽

Microbial Diversity ◽

Growth And Yield ◽

Rrna Gene ◽

Plant Growth Promoting Bacteria ◽

Microbial Composition ◽

Pyroligneous Acid ◽

Plant Growth Promoting ◽

Growth Promoting

Pyroligneous acid (PA) is often used in agriculture as a plant growth and yield enhancer. However, the influence of PA application on soil microorganisms is not often studied. Therefore, in this study, we investigated the effect of PA (0.01–5% w/w in soil) on the microbial diversity in two different soils. At the end of eight weeks of incubation, soil microbial community dynamics were determined by Illumina-MiSeq sequencing of 16S rRNA gene amplicons. The microbial composition differed between the lower (0.01% and 0.1%) and the higher (1% and 5%) concentration in both PA spiked soils. The lower concentration of PA resulted in higher microbial diversity and dehydrogenase activity (DHA) compared to the un-spiked control and the soil spiked with high PA concentrations. Interestingly, PA-induced plant growth-promoting bacterial (PGPB) genera include Bradyrhizobium, Azospirillum, Pseudomonas, Mesorhizobium, Rhizobium, Herbaspiriluum, Acetobacter, Beijerinckia, and Nitrosomonas at lower concentrations. Additionally, the PICRUSt functional analysis revealed the predominance of metabolism as the functional module’s primary component in both soils spiked with 0.01% and 0.1% PA. Overall, the results elucidated that PA application in soil at lower concentrations promoted soil DHA and microbial enrichment, particularly the PGPB genera, and thus have great implications for improving soil health.

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Alone Yet Not Alone: Frankia Lives Under the Same Roof With Other Bacteria in Actinorhizal Nodules

Frontiers in Microbiology ◽

10.3389/fmicb.2021.749760 ◽

2021 ◽

Vol 12 ◽

Author(s):

Faten Ghodhbane-Gtari ◽

Timothy D’Angelo ◽

Abdellatif Gueddou ◽

Sabrine Ghazouani ◽

Maher Gtari ◽

...

Keyword(s):

16S Rrna ◽

Plant Growth ◽

16S Rrna Gene ◽

Root Nodules ◽

Actinorhizal Plants ◽

Rrna Gene ◽

Plant Growth Promoting Bacteria ◽

Metagenomic Sequencing ◽

Plant Growth Promoting ◽

Growth Promoting

Actinorhizal plants host mutualistic symbionts of the nitrogen-fixing actinobacterial genus Frankia within nodule structures formed on their roots. Several plant-growth-promoting bacteria have also been isolated from actinorhizal root nodules, but little is known about them. We were interested investigating the in planta microbial community composition of actinorhizal root nodules using culture-independent techniques. To address this knowledge gap, 16S rRNA gene amplicon and shotgun metagenomic sequencing was performed on DNA from the nodules of Casuarina glauca. DNA was extracted from C. glauca nodules collected in three different sampling sites in Tunisia, along a gradient of aridity ranging from humid to arid. Sequencing libraries were prepared using Illumina NextEra technology and the Illumina HiSeq 2500 platform. Genome bins extracted from the metagenome were taxonomically and functionally profiled. Community structure based off preliminary 16S rRNA gene amplicon data was analyzed via the QIIME pipeline. Reconstructed genomes were comprised of members of Frankia, Micromonospora, Bacillus, Paenibacillus, Phyllobacterium, and Afipia. Frankia dominated the nodule community at the humid sampling site, while the absolute and relative prevalence of Frankia decreased at the semi-arid and arid sampling locations. Actinorhizal plants harbor similar non-Frankia plant-growth-promoting-bacteria as legumes and other plants. The data suggests that the prevalence of Frankia in the nodule community is influenced by environmental factors, with being less abundant under more arid environments.

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