IAA Production Research Articles

Novel synergism of Cedecea lapagei KU14 and Bacillus subtilis KU21 for sustainable productivity of Rosmarinus officinalis in Northwest Himalayas

The current study aimed to assess the scope of native potential endophytic bacteria Bacillus subtilis KU21, Pseudomonas aeruginosa SI12 and Cedecea lapagei KU14 for synergistic effect to develop as consortium biofertilizer of rosemary. All the three strains were assessed for multiple plant growth promoting (PGP) traits viz., P solubilization, siderophore and Indole-3-acetic acid production (IAA). Consortia of strains (KU21, SI12 and KU14) showed significantly high production of IAA, siderophore production and P-solubilization over the single inoculants. All the isolates i.e., KU21, SI12 and KU14 individually and their consortia were assessed for in vivo growth studies of rosemary under net house conditions. Combined application of these strains significantly increased growth parameters of rosemary over single inoculation and untreated control. Based on the results, two consortia i.e., B. subtilis KU21+ C. lapagei KU14 and B. subtilis KU21+ C. lapagei KU14+ P. aeruginosa SI12 were further evaluated under field conditions. The combined application of B. subtilis KU21+ C. lapagei KU14 significantly improved rosemary growth parameters (at vegetative and flowering stage), nutrient acquisition, and soil quality parameters over uninoculated control. This is the first field report that describes the efficacy of novel endophytic strains i.e., B. subtilis KU21+ C. lapagei KU14 for improving rosemary production and soil health simultaneously, hence may be recommended for sustainable production of R. officinalis in Northwest Himalayan region.

Molecular Identification of Endophytic Bacteria from Silybum marianum and Their Effect on Brassica napus Growth under Heavy Metal Stress

Silybum marianum has been used for a variety of purposes all over the world. This plant is used to treat cancer, liver disease, and inflammation. Eleven endophytic bacteria were isolated from S. marianum collected from heavy metal polluted sites and identified using 16s rRNA sequencing in the current investigation. Three isolates stood out for having many features, including heavy metal resistance, plant growth stimulation, plant hormones, heavy metal toxicity remediation, and antibacterial action. SJLC (6.06 µg/L) and SJRB (5.98 µg/L) were the greatest producers of IAA among the isolates and were identified as Bacillus sp. and Lysinibacillus sp., respectively. Root and shoot length have improved as a result of IAA production. The SJLC was found to be effective against four of the pathogens tested. The strain SJLC showed the most activity against Bacillus cereus with a 20 mm zone of inhibition, followed by the isolate SJRB, which showed a 16 mm zone of inhibition against B. cereus. The same isolates also show inhibition against X. campestris. Almost majority of the Brassica napus plants inoculated with bacterial isolates were able to translocate and degrade heavy metals like Cr. Therefore, it was concluded that these isolates are capable to grow in highly polluted environments.

Alleviation of cold stress in wheat with psychrotrophic phosphorus solubilizing Acinetobacter rhizosphaerae EU-KL44.

Low-temperature stress can seriously impair plant physiology. Chilling injury leads to a complex array of cellular dysfunctions, and symptoms include chlorosis, sterility, loss of vigor, wilting, and even death of the plants. Furthermore, phosphorus limitations additionally halt the growth of plants. Low-temperature adaptive plant growth-promoting microbes through various direct and indirect mechanisms help in the survival of plants under stress conditions. The present investigation deals with isolation of P-solubilizing psychrotrophic bacteria from diverse cultivars of wheat grown in the Keylong region of Himachal Pradesh. A total of 33 P-solubilizing bacterial isolates were obtained. P-solubilizers were screened for different plant growth-promoting (PGP) attributes of K and Zn solubilization, production of IAA, siderophores, and different hydrolytic enzymes. Among 33 P-solubilizers, 8 efficient strains exhibiting multiple PGP attributes were used as bioinoculants for wheat under low-temperature stress in different in vitro and in vivo experiments. The psychrotrophic bacterial isolates positively influenced the growth and physiological parameters as well as nutrient uptake and yield of wheat and efficiently alleviated low-temperature stress. The potential of low-temperature stress adaptive and PGP microbes can be utilized in agricultural sector for amelioration of low-temperature stress and plant growth promotion. The present study deals with the isolation of psychrotrophic P-solubilizers with multiple PGP attributes and their role in alleviation of cold stress in wheat.

PGPR Promotes the Recovery of Submerged Macrophytes via Indigenous Microbiome Modulations under Combined Abiotic Stress

The restoration of submerged macrophytes is commonly limited by abiotic stress. Here, we isolated PGPR strains from the rhizosphere of submerged macrophytes using ACC deaminase selective medium, and evaluated their growth promoting effects on Vallisneria natans (V. natans) under low light intensity and (or) high sediment organic matter load, and also explored the indigenous microbiome response of V. natans seedlings to PGPR inoculants. Ten isolates were chosen from the 252 isolated strains based on the ACC deaminase activity and the production of IAA and siderophore. M1 (Pseudomonas vancouverensis) and E15 (Enterobacter ludwigii) had the best growth promoting effects under low light stress and under double stress of low light and high sediment organic matter load, and the shoot height increased by 36% and 46%, respectively. The results of indigenous microbiome analysis showed that PGPR inoculants could regulate the relative abundance of unclassified_f_Enterobacteriaceae and improve the α-diversity of the rhizosphere bacterial community. Under high sediment organic matter load, inoculation of PGPR obviously shifted the β-diversity of rhizosphere bacterial communities to promote the early growth of V. natans. This study expands the application of plant–microbe interaction in the field of freshwater ecological restoration.

Genomic Insights and Functional Analysis Reveal Plant Growth Promotion Traits of Paenibacillus mucilaginosus G78.

Paenibacillus mucilaginosus has widely been reported as a plant growth-promoting rhizobacteria (PGPR). However, the important genomic insights into plant growth promotion in this species remain undescribed. In this study, the genome of P. mucilaginosus G78 was sequenced using Illumina NovaSeq PE150. It contains 8,576,872 bp with a GC content of 58.5%, and was taxonomically characterized. Additionally, a total of 7337 genes with 143 tRNAs, 41 rRNAs, and 5 ncRNAs were identified. This strain can prohibit the growth of the plant pathogen, but also has the capability to form biofilm, solubilize phosphate, and produce IAA. Twenty-six gene clusters encoding secondary metabolites were identified, and the genotypic characterization indirectly proved its resistant ability to ampicillin, bacitracin, polymyxin and chloramphenicol. The putative exopolysaccharide biosynthesis and biofilm formation gene clusters were explored. According to the genetic features, the potential monosaccharides of its exopolysaccharides for P. mucilaginosus G78 may include glucose, mannose, galactose, fucose, that can probably be acetylated and pyruvated. Conservation of the pelADEFG compared with other 40 Paenibacillus species suggests that Pel may be specific biofilm matrix component in P. mucilaginosus. Several genes relevant to plant growth-promoting traits, i.e., IAA production and phosphate solubilization are well conserved compared with other 40 other Paenibacillus strains. The current study can benefit for understanding the plant growth-promoting traits of P. mucilaginosus as well as its potential application in agriculture as PGPR.

Characterization of Plant Growth Promoting Rhizobacteria From Seasonal Flower Beds

The present investigations were carried out to screen the PGPR isolates from five separate seasonal flower beds (Catharanthus roseus, Portulaca grandiflora, Celosia argentea, Gomphrena globosa and Impatiens balsamina) of Curzon Hall, University of Dhaka. The bacterial load of the collected soil samples ranged in between 7.60 ± 6.01 × 106 and 9.49 ± 5.44× 108 cfu/g, 5.34 ± 4.06×106 and 13.4 ± 4.8×106 cfu/g and 1.01 ± 0.59×106 and 1.19 ± 0.95×108 cfu/g on Nutrient Agar (NA), Luria-Bertani (LB) and Yeast Extract Mannitol Agar (YEMA), respectively. All the selected eight isolates were Gram positive and rod shaped. All isolates were found to be IAA producer and 7 showed varying levels of phosphate solubilizing activity. IAA production and phosphate (P) solubilization of the selected isolates ranged in between 9.76 ± 5.98 to 17.99 ± 1.865 U/ml, and 1.17 ± 0.59 to 1.84 ± 0.499 mg/l. Maximum production of both IAA and phosphate solubilization was achieved in 24h of incubation period at 37°C and pH 7.0. Germination test against Mung Bean (Vigna radiata) revealed positive plant growth promoting activities and could be used as PGPR inoculant. Dhaka Univ. J. Biol. Sci. 31(2): 321-328, 2022 (July)

New Insights on Endophytic Microbacterium-Assisted Blast Disease Suppression and Growth Promotion in Rice: Revelation by Polyphasic Functional Characterization and Transcriptomics

Plant growth-promoting endophytic microbes have drawn the attention of researchers owing to their ability to confer fitness benefits in many plant species. Here, we report agriculturally beneficial traits of rice-leaf-adapted endophytic Microbacterium testaceum. Our polyphasic taxonomic investigations revealed its identity as M. testaceum. The bacterium displayed typical endophytism in rice leaves, indicated by the green fluorescence of GFP-tagged M. testaceum in confocal laser scanning microscopy. Furthermore, the bacterium showed mineral solubilization and production of IAA, ammonia, and hydrolytic enzymes. Tobacco leaf infiltration assay confirmed its non-pathogenic nature on plants. The bacterium showed antifungal activity on Magnaporthe oryzae, as exemplified by secreted and volatile organic metabolome-mediated mycelial growth inhibition. GC-MS analysis of the volatilome of M. testaceum indicated the abundance of antimicrobial compounds. Bacterization of rice seedlings showed phenotypic traits of MAMP-triggered immunity (MTI), over-expression of OsNPR1 and OsCERK, and the consequent blast suppressive activity. Strikingly, M. testaceum induced the transcriptional tradeoff between physiological growth and host defense pathways as indicated by up- and downregulated DEGs. Coupled with its plant probiotic features and the defense elicitation activity, the present study paves the way for developing Microbacterium testaceum-mediated bioformulation for sustainably managing rice blast disease.

Combined application of allantoin and strain JIT1 synergistically or additively promotes the growth of rice under 2, 4-DCP stress by enhancing the phosphate solubility, improving soil enzyme activities and photosynthesis

Environmental pollution by 2, 4 dichlorophenol (2, 4-DCP) has become a widespread concern due to its detrimental influence on human and natural ecosystem. With the increasing accumulation of 2, 4-DCP in soil, it is of great significance to explore some appropriate approaches for enhancing plant tolerance to 2, 4-DCP stress. In the current study, a strain resistant to 2, 4-DCP was obtained from the tall fescue rhizosphere soil and named as Pseudomonas sp. JIT1. The strain JIT1 exhibited several remarkable plant growth-promoting traits, including the production of IAA, fixation of biological nitrogen and solubilization of phosphate. The inoculation of strain JIT1 significantly increased biomass, photosynthesis, antioxidant levels, chlorophyll contents and the osmotic substance contents in rice seedlings exposed to 2, 4-DCP. Meanwhile, inoculation of strain JIT1 also enhanced activities of soil alkaline phosphatase, urease, sucrase and cellulase. Moreover, under 2, 4-DCP stress, the content of allantoin in seedlings significantly increased and the pretreatment of exogenous allantoin noticeably ameliorated the negative effects caused by 2, 4-DCP stress in rice seedlings. Interesting, allantoin treatment also enhanced phosphate solubilization properties of strain JIT1. The chlorophyll contents, photosynthesis and osmotic substance further increased by combination use of strain JIT1 and allantoin, which improved the growth of seedlings, most likely to be attributed to the synergistic or additive effect between allantoin and strain JIT1. The results of this study highlight the important roles of combined use of strain JIT1 and allantoin for improving the tolerance of rice to 2, 4-DCP to stress.

Screening and Identification of the Rhizosphere Fungal Communities Associated with Land Reclamation in Egypt

Soil fungi are a wide range of microorganisms that play an essential role in enhancing the available nutrients in the soil for plants. In the current study, to study the fungal association with newly reclaimed land in Egypt, 22 composite soil samples were screened and characterized from citrus and olive orchard soil in contrast to a control soil that had never been cultivated (a nearby desert). The isolates were identified and tested for P solubilization and IAA production to highlight their potential as biofertilizers while the sampled soil was characterized. The physicochemical characteristics of the orchard’s soil sample had a high relative mean moisture content, and the C/N ratio were 45.24% and 16.8% compared with desert lands of 32.80% and 8.12%, respectively, while a higher pH was recorded for desert lands. A total of 272 fungal isolates yielded 27 filamentous fungal species. Based on ITS molecular identification, the 27 isolates belonged to phyla Ascomycota, from eight genera. Twelve species were positive in producing a phosphate clearance zone around the fungal colony growth, while ten species were able to release IAA in vitro with different tryptophan concentrations under different pH values. When known pathogenic fungi were excluded, Aspergillus tubingensis and A. fumigatus were the highest IAA producers and can solubilize phosphorus. The screening and identification of the fungal diversity of the newly reclaimed land provided insights into potential phosphate solubilizers and plant phytohormones producers (i.e., IAA). Overall, the obtained results can provide primary knowledge that indicates the great potential fungal ability to develop biofertilizers for application in improving the production of immature soil for agriculture reclamation processes and practices.

Impact of soil temperature, pH and carbon dioxide on the population and efficiency of fluorescent pseudomonad in the rhizosphere soil of Pokkali rice

The present study was aimed at the evaluation of soil temperature, pH and carbon dioxide evolution on the number and efficiency of fluorescent pseudomonads around the root system of Pokkali rice at Vytilla in Ernakulam district of Kerala. Two plots (40 m2) comprising control (without application of Pseudomonas fluorescens) and P. fluorescens treated plants were used for the field experiment. The isolates of fluorescent Pseudomonads or Pseudomonas fluorescence were counted and their efficiency was assessed for IAA, ammonia, HCN and siderophore production. Simultaneously, soil temperature, pH, and carbon dioxide evolution were also recorded. A total of 6 fluorescent pseudomonads (VPJU, VPJL, VPAU1, VPAU2, VPAU3 and VPAU4) were found during the crop period. All the isolates produced IAA and ammonia with varying degrees of intensity. Three isolates (VPAU1, VPAU3 and VPAU4) produced HCN, and no microbial isolates produced siderophore. The effect of soil temperature, pH, EC and carbon dioxide evolution was correlated with the number of fluorescent pseudomonads in the soil. The bacteria were significantly afflicted by pH and EC, whereas soil temperature and CO2 evolution did not show any effect on the number of fluorescent pseudomonads. There was no significant influence of soil temperature, pH, EC and carbon dioxide evolution on indole acetic acid production, ammonia, and HCN production. Inoculated Pseudomonas fluorescence did not survive in Pokkali rice fields. However, further studies are needed for at least three seasons in Pokkali soils to confirm the results of the present study.

A Culture-dependent Study of Bacteria Associated with the Roots of Organically and Inorganically Cultivated Rice Accessions

Rice is one of the most important staple foods consumed by the maximum human population in the world. India possesses a large number of traditionally maintained rice landraces which are cultivated using traditional practices or minimal fertilizer input. Such landraces may be associated with unique microbial flora adapted to various biotic and abiotic stresses. This work aimed to study the diversity of bacteria associated with roots of 18 randomly selected landraces from Jawhar, Maharashtra, grown under organic cultivation practices, and the cv. Indrayani from Mulshi, Maharashtra, grown using conventional cultivation practices. The cultivation-based approach yielded a total of 40 bacterial isolates. Isolates were purified and identified by sequencing the 16S rDNA region. Isolates were tested for plant growth-promoting characteristics such as nitrogen fixation, phosphate solubilization, IAA production, etc. 22 isolates tested positive for nitrogen fixation either by acetylene reduction or the presence of nifH gene, 27 had phosphate solubilization and 39 had IAA production ability. Bacterial diversity demonstrated the dominance of phylum Proteobacteria and isolates belonging to 11 genera and 23 species e.g., Stenotrophomonas sp., Bradyrhizobium sp. etc. PCA showed a clear difference between bacterial diversity associated with landraces and cv. Indrayani. Our findings provide a basis for further investigations into the role and impact of microbial communities in plant growth promotion. Rice is one of the most important staple foods consumed by the maximum human population in the world. India possesses a large number of traditionally maintained rice landraces which are cultivated using traditional practices or minimal fertilizer input. Such landraces may be associated with unique microbial flora adapted to various biotic and abiotic stresses. This work aimed to study the diversity of bacteria associated with roots of 18 randomly selected landraces from Jawhar, Maharashtra, grown under organic cultivation practices, and the cv. Indrayani from Mulshi, Maharashtra, grown using conventional cultivation practices. The cultivation-based approach yielded a total of 40 bacterial isolates. Isolates were purified and identified by sequencing the 16S rDNA region. Isolates were tested for plant growth-promoting characteristics such as nitrogen fixation, phosphate solubilization, IAA production, etc. 22 isolates tested positive for nitrogen fixation either by acetylene reduction or the presence of nifH gene, 27 had phosphate solubilization and 39 had IAA production ability. Bacterial diversity demonstrated the dominance of phylum Proteobacteria and isolates belonging to 11 genera and 23 species e.g., Stenotrophomonas sp., Bradyrhizobium sp. etc. PCA showed a clear difference between bacterial diversity associated with landraces and cv. Indrayani. Our findings provide a basis for further investigations into the role and impact of microbial communities in plant growth promotion.

Draft Genome Sequence of Enterobacter cloacae S23 a Plant Growth-promoting Passenger Endophytic Bacterium Isolated from Groundnut Nodule Possesses Stress Tolerance Traits.

This study aims to reveal the passenger endophytic bacterium Enterobacter cloacae S23 isolated from groundnut nodules and to underpin the molecular mechanism and genes responsible for abiotic stress tolerance. A variety of microorganisms that contribute to nodulation and encourage plant development activity in addition to the nodulating Rhizobium. Passenger endophytes (PE) are endophytes that accidentally penetrate the plant without any selective pressure keeping them in the interior tissue of the plant. PE possesses characteristics that encourage plant development and boost output while reducing pathogen infection and improving biotic and abiotic stress tolerance. However, there is a lack of molecular evidence on the passenger endophyte-mediated alleviation of abiotic stresses. This study was formulated to reveal the draft genome sequence of Enterobacter cloacae S23, as well as genes and characteristics involved in plant growth promotion and stress tolerance. The data were submitted to PATRIC and the TORMES-1.0 Unicyclker tools were used to conduct a complete genome study of Enterobacter cloacae S23. The TORMES-1.0 platform was used to process the reads. RAST tool kit (RASTtk) was used to annotate the S23 sequence. The plant growth-promoting traits such as indole acetic acid production, siderophore secretion, production of extracellular polysaccharides, biofilm formation, phosphate solubilization, and accumulation of osmolytes were examined under normal, 7% NaCl and 30% polyethylene glycol amended conditions to determine their ability to withstand salt and moisture stressed conditions, respectively. We report the size of Enterobacter cloacae S23 is 4.82Mb which contains 4511 protein-coding sequences, 71 transfer RNA genes, and 3 ribosomal RNA with a G+C content of DNA is 55.10%. Functional analysis revealed that most of the genes are involved in the metabolism of amino acids, cofactors, vitamins, stress response, nutrient solubilization (kdp, pho, pst), biofilm formation (pga) IAA production (trp), siderophore production (luc, fhu, fep, ent, ybd), defense, and virulence. The result revealed that E. cloacae S23 exhibited multiple plant growth-promoting traits under abiotic stress conditions. Our research suggested that the discovery of anticipated genes and metabolic pathways might characterise this bacterium as an environmentally friendly bioresource to support groundnut growth through several mechanisms of action under multi-stresses.

Exploration of Saurashtra Soil PGPR Strain and its Attributes in Crop Productivity by Pot Plant Study

The impact of rhizobacteria with PGPR trait in current agriculture practices is expanding its horizons at large in research and practices. The urge of improvised crop productivity and disease management for economically important myriad crops like cereal plant, and angiosperms, monocots, dicots need to address in versatile manner with integrated approach. The need of a potent trait of PGPR rhizobacteria and its real time application in field trials is more challenging and to address the same, the present research study has been carried out. The present study encompassing the one phase of the project is to isolate the Rhizobial trait from the soil sample followed by the screening of the potent traits. Total 4 potent rhizobacterial isolates have been screened among 41 bacterial isolates from different sites of the Saurashtra region. Qualitative and quantitative characterization of growth promotion factors such as HCN production, ammonia production, IAA production, and siderophore production of the isolates (KS2, KC8, KC9, and KC11 showed) were carried out. Among 21 isolates the 4 isolates KS2, KC8, KC9, and KC11showed the highest growth parameter production and have been stated as PGPR traits. Employing One way ANOVA a statistical design, the shoot and root length effect has been studied in detail with the individual strains KS2, KC8, KC9, and KC11 along with control. The study is quite encouraging with improved root length 10.54±0.33 cm and shoot length 27.20 ± 0.8 cm respectively. The future prospect of this study can be highlighted in long-term with further analysis on consortial development and its field trial applications.

Co-inoculation of multi-trait plant growth promoting rhizobacteria promotes growth and nutrient assimilation of transplant Aman rice (cv. BRRI dhan49)

BACKGROUND: Plant growth-promoting rhizobacteria (PGPR) are the rhizosphere bacteria that can enhance plant growth by a wide variety of mechanisms. This study was conducted to assess the effects of plant growth-promoting rhizobacteria on growth and nutrient assimilation of rice. METHODOLOGY: Seeds of transplant Aman rice (cv. BRRI dhan49) were collected from Bangladesh Rice Research Institute (BRRI). Pot experiment was conducted with rice plant inoculated with two PGPR isolates MQ1 (Zinc solubilizing, IAA producing, phosphate solubilizing and N2-fixing) and MQ2 (Zinc solubilizing, phosphate solubilizing and N2-fixing) with addition of three different levels of chemical fertilizers (FR0.0 no fertilizer, FR0.5 half of the recommended dose, FR1.0 full of the recommended dose of fertilizers) following Completely Randomized Design with three replications. Plant height at different days after transplanting, number of tillers hill-1 and biomass yield were recorded. Plant samples were analyzed for N, P, Ca, Mg, S, Fe, Zn, Mn, Cu and Cd contents. KEY FINDINGS: Rice plants inoculated with the PGPR both individually or in consortium along with different doses of fertilizers showed an improved plant growth and increased biomass production. Highest plant height (74.057±3.164 cm) and maximum number of tillers hill-1 (13.000±2.082) were recorded in PGPRMQ1RF1.0 treatment and the highest biomass production (10.275±0.541 t ha-1) was recorded in PGPRCONS.RF1.0. Nitrogen content and uptake of the individual PGPR treated rice plants was also found to be higher in comparison with the uninoculated control plants. Besides these iron and zinc content of the treated rice plants was also found to be higher in comparison with the uninoculated control plants. N (0.268±0.046), P (0.626±0.095), Fe (6.062094±A), Zn (1.237±0.197) and Mn (11.908±1.879) uptake were observed higher in PGPRMQ1RF1.0 treatment. CONCLUSION: PGPR inoculation has immense potential to be used as agricultural crop inoculants as they promote plant growth as well as nutrient assimilation of rice.

Plant growth promoting, biochemical and antifungal properties of microbes isolated from cow dung

Cow dung is a rich source of microbial diversity and being used since long time in India for seed treatment, plastering cut ends of vegetative propagated plant parts and sprinkling of diluted solution on crops. In present study, microbes from fresh cow dung of indigenous cow were isolated and biochemically characterized. Cow dung enriched with diversity of microorganisms in different medium i.e 38 x 106cfu g-1 (Nutrient agar), 26.0 x 106 cfu g-1 (Actinomycetes isolation agar), 36 x 106 cfu g-1 (Kings B agar), 16 x 106 cfu g-1(CV agar),13 x 106 cfu g-1 (Methyl red), 15 x 106 cfu g-1 (Pikovskyas agar), 30 x 106 cfu g-1 (CRYEMA), Azospirillum 70 x 106 cfu g-1 (N-free maleate) and 30 x 106 cfu g-1(Jenson agar medium). Based on microbial enumeration, total 18 bacterial isolates were selected for biochemical, PGPR characterization and biocontrol activity. All isolates were tested positive for phosphate and Zn solubilisation. Isolate CD2, CD5, CD13, CD14 and CD19 were tested highly positive for zinc, phosphate, K-solubilisation, IAA and amylase production. Test isolates CD2, CD5, CD6, CD7, CD10 and CD13 were tested highly positive for β-galactosidase activity, ornithine utilization, nitrate reduction, citrate utilization, malonate utilization, esculin hydrolysis, trehalose, glucose and lactose utilization. All isolated microbes tested for biocontrol activity (antifungal property) against standard pathogen procured from microbial type culture collection (MTCC), i.e. C. gloeosporioides (MTCC 2190), F. oxysporum (MTCC 10247), C. fimbriota (MTCC 2281) and P. aphanidermatum (MTCC 284). CD2, CD34 and CD20 isolates significantly inhibited the growth of C. gloeosporioides and P. aphanidermatum. Result of the study advocates that cow dung and cow dung based formulations are cheap source for soil, plant health and management of Colletotrichum gloeosporioides, P. aphanidermatum and Fusarium oxysporum in various crops.

Produkcija indolnih jedinjenja od strane rizobijalnih bakterija

Rhizobial bacteria, besides nitrogen fixation in symbiosis with legumes, can colonize the roots of nonlegumes and promote their growth by different mechanisms, independently of N2 fixation. Owing to this, rhizobia are considered a plant growth-promoting rhizobacteria (PGPR). Some of the mechanisms of PGPR activity are phytohormone production. Selection of rhizobia which possess some of PGP traits in vitro is an important step prior to testing their effects on plants in controlled conditions or field. In this work the ability of indole-3-acid (IAA) production, one of the most important phytohormone of the auxin class, was evaluated in different rhizobial strains. The investigated rhizobial strains were isolated from alfalfa (belonged to the genera Ensifer and Rhizobium) and from soybean (Bradyrhizobium and Rhizobium). Strains of all investigated genera produced IAA in the presence of L-tryptophan as precursor, where Ensifer strains produced the highest amount of IAA (more than 200 µg ml-1 ), followed by Rhizobium, while Bradyrhizobium strains produced the least amount of IAA (with some exceptions up to 15 µg ml-1 ). With the increase of L-tryptophan concentration, the amount of IAA produced usually grew. Strains with high IAA production indicate their plant growth promoting potential and represent the candidates for evaluation of their effects in non-legumes in controlled and field conditions.

Isolation, Screening, and Molecular Characterization of Rhizosphere Derived Potential Biofertilizer from Different Crops Land for Sustainable Agriculture and Environment

Overpopulation in world has created immense pressure on agricultural land to increase crops production by using excess chemical fertilizers, pesticides, and plant growth regulators. Nowadays, biofertilizer is one of the best concerns of research interest for sustainable development in agriculture and environment. About 30 soil bacteria were isolated from three different locations in Bangladesh by growing on nitrogen-free selective media and primarily had been categorized based on colony features. However, to short out the biofertilizer and biocontrol potential bacteria several assay had been conducted including nitrogen-fixing assay, ammonia production assay, phosphate solubilizing assay, IAA production assay, siderophores production assay, amylase production assay, biocontrol assay, and seed germination bioassay. Different species of Rhizobium, Bacillus, Paraburkholderia, Priestia, Arthrobacter, Pseudarthrobacter, Rhodanobacter, Flavobacterium, Mucilaginibacter, and Sphingomonas were identified by analyzing 16S rRNA gene partial sequence analysis by BLASTn that revealed many of these act as biofertilizer. Moreover, the antibiotic resistance tests of biofertilizer potential isolates and all others intensive data analysis in respect of biofertilizer functionality revealed that Paraburkholderia sacchari is the best while Priestia megaterium, Bacillus zanthoxyli, Arthrobacter globiformis, and Bacillus wiedmanni have also the potentiality to be biofertilizer. The outcome will help the researchers and industries to develop biofertilizer for crops plant.

Effects on gene expression during maize-Azospirillum interaction in the presence of a plant-specific inhibitor of indole-3-acetic acid production.

Amongst the sustainable alternatives to increase maize production is the use of plant growth-promoting bacteria (PGPB). Azospirillum brasilense is one of the most well-known PGPB being able to fix nitrogen and produce phytohormones, especially indole-3-acetic acid - IAA. This work investigated if there is any contribution of the bacterium to the plant's IAA levels, and how it affects the plant. To inhibit plant IAA production, yucasin, an inhibitor of the TAM/YUC pathway, was applied. Plantlets' IAA concentration was evaluated through HPLC and dual RNA-Seq was used to analyze gene expression. Statistical differences between the group treated with yucasin and the other groups showed that A. brasilense inoculation was able to prevent the phenotype caused by yucasin concerning the number of lateral roots. Genes involved in the auxin and ABA response pathways, auxin efflux transport, and the cell cycle were regulated by the presence of the bacterium, yucasin, or both. Genes involved in the response to biotic/abiotic stress, plant disease resistance, and a D-type cellulose synthase changed their expression pattern among two sets of comparisons in which A. brasilense acted as treatment. The results suggest that A. brasilense interferes with the expression of many maize genes through an IAA-independent pathway.

Isolation and Characterization of Plant Growth promoting Rhizobacteria from Bamboo Rhizosphere and Their Role in Plant Growth Promotion

Plant growth-promoting rhizobacteria (PGPR) are a group of root-associated bacteria that intimately interact with the plant roots and consequently enhance growth by extemporising nutrient retrieval or phytohormone production. We isolated and screened indigenous phosphate solubilising and auxinproducing PGPR from bamboo rhizosphere. 66 soil samples from bamboo (Bambusa nutans subsp. cupulata, B. balcooa and B. tulda) rhizospheres were collected from Dhanusha, Mahottari and Sarlahi districts, Nepal. 120 isolates of PGPR were obtained by serial dilution method in (PVK) agar and Luria Bertani agar. 92 out of 120 isolates of PGPR with the ability to solubilise phosphate were selected based on the halo colony ratio in PVK agar medium and auxin production in Luria Bertani agar. Among them, six isolates having high phosphate solubilising index and high production capacity of indole-3-acetic acid were further screened. Biochemical analysis revealed that these isolates belonged to the genus Pseudomonas. Phosphate solubilising index and indole-3- acetic acid production by six isolates ranged from 4.19±0.8 to 7.65±1.3, and IAA production ranged from 72.93±0.2 to 82.48±0.9µg/ml respectively. These isolates significantly increased shoot length (13.26±0.56cm), shoot fresh weight (16.26±1.02mg), shoot dry weight (10.56±0.09mg), root length (4.9±0.5cm), root fresh weight (7.56±1.05mg), root dry weight (3.21±0.01mg), and chlorophyll ‘a’ and chlrophyll‘b’ and carotenoid (2.16±0.01mg/g, 1.19±0.06mg/g and 0.92±0.01mg/g respectively) of B. nutans subsp. cupulata seedlings. This study suggests that PGPR isolated from bamboo rhizosphere demonstrated outstanding contribution to the growth promotion of seedlings of B. nutans subsp. cupulata as compared to negative control.

Common scab disease-induced changes in geocaulosphere microbiome assemblages and functional processes in landrace potato (Solanum tuberosum var. Rongpuria) of Assam, India.

Common scab (CS) caused by pathogenic Streptomyces spp. plays a decisive role in the qualitative and quantitative production of potatoes worldwide. Although the CS pathogen is present in Assam's soil, disease signs and symptoms are less obvious in the landrace Rongpuria potatoes that indicate an interesting interaction between the plant and the geocaulosphere microbial population. Toward this, a comparative metagenomics study was performed to elucidate the geocaulosphere microbiome assemblages and functions of low CS-severe (LSG) and moderately severe (MSG) potato plants. Alpha diversity indices showed that CS occurrence modulated microbiome composition and decreased overall microbial abundances. Functional analysis involving cluster of orthologous groups (COG) too confirmed reduced microbial metabolism under disease incidence. The top-three most dominant genera were Pseudomonas (relative abundance: 2.79% in LSG; 12.31% in MSG), Streptomyces (2.55% in LSG; 5.28% in MSG), and Pantoea (2.30% in LSG; 3.51% in MSG). As shown by the high Pielou's J evenness index, the potato geocaulosphere core microbiome was adaptive and resilient to CS infection. The plant growth-promoting traits and potential antagonistic activity of major taxa (Pseudomonads, non-pathogenic Streptomyces spp., and others) against the CS pathogen, i.e., Streptomyces scabiei, point toward selective microbial recruitment and colonization strategy by the plants to its own advantage. KEGG Orthology analysis showed that the CS infection resulted in high abundances of ATP-binding cassette transporters and a two-component system, ubiquitous to the transportation and regulation of metabolites. As compared to the LSG metagenome, the MSG counterpart had a higher representation of important PGPTs related to 1-aminocyclopropane-1-carboxylate deaminase, IAA production, betaine utilization, and siderophore production.