Novel nucleus-localized GRAM protein encoding OsGRAM57 gene enhances salt tolerance through ABA-dependent pathway and modulated carbohydrate metabolism.

GRAM (Glucosyltransferases-like GTPase activators and Myotubularin) domain-encoding proteins play pivotal roles in plant growth and responses to biotic stresses. Yet, their influence on abiotic stress responses has remained enigmatic. This study unveils a novel nucleus-localized OsGRAM57, a GRAM protein-encoding gene and its profound regulatory functions in enhancing salt stress tolerance using Arabidopsis thaliana as a model plant. OsGRAM57-OEX (OsGRAM57-OEX) lines displayed significant enhancement in salt tolerance, modulated physiological, biochemical, K+/Na+ ratios, and enzymatic indices as compared to their wild-type (WT). Furthermore, OsGRAM57-OEX seedlings demonstrate increased levels of endogenous abscisic acid (ABA) and other phytohormones, while metabolic profiling revealed enhanced carbohydrate metabolism. Delving into the ABA signaling pathway, OsGRAM57 emerged as a central regulator, orchestrating the expression of genes crucial for salt stress responses, carbohydrate metabolism, and ABA signaling. The observed interactions with target genes and transactivation assays provided additional support for OsGRAM57's pivotal role. These findings underscore OsGRAM57's positive influence on the ABA pathway and affirm its capacity to enhance salt tolerance through an ABA-dependent pathway and fine-tuned carbohydrate metabolism. In summary, this new study reveals the previously undiscovered regulatory roles of OsGRAM57 in Arabidopsis abiotic stress responses, offering promising ways for strengthening plant resilience in the face of adverse environmental conditions.

Endophytic bacilli from Cyamopsis tetragonoloba (L.) Taub. induces plant growth and drought tolerance.

Cyamopsis tetragonoloba (L.) Taub. (guar) is a commercially important crop known for its galactomannan content in seeds. Drought stress is a significant global concern that compromises the productivity of major legumes including guar. The endophytic microbes associated with plants play a significant role in enhancing plant growth and modulating the impact of abiotic stress(s). The present study involved the isolation of 73 endophytic bacteria from the guar seeds of drought-tolerant (RGC-1002 and RGC-1066) and sensitive (Sarada and Varsha) varieties. Based on multiple PGP attributes and drought tolerance, at 50% PEG6000 w/v, 11 efficient isolates were selected and identified through 16S rRNA gene sequencing. Isolates belonging to ten different species of bacilli including Cytobacillus oceanisediminis, Mesobacillus fermenti, Peribacillus simplex from sensitive and Bacillus zanthoxyli, B. safensis, B. velezensis, B. altitudinis, B. licheniformis, B. tequilensis, and B. paralicheniformis isolated from tolerant varieties. A greenhouse experiment with a drought-sensitive guar variety demonstrated that inoculation of selected isolates showed comparatively better plant growth, higher relative water content (RWC), decreased carbon isotope discrimination ratio (Δ13C), increased chlorophyll, carotenoids, anthocyanin, and proline content, decreased malondialdehyde (MDA) and modulated defense enzymes as compared to their uninoculated controls. Tolerant variety isolates B. tequilensis NBRI14G and B. safensis NBRI10R showed the most promising results in improving plant growth and also drought stress tolerance in guar plants. This study represents for the first time that seed endophytic bacterial strains from guar can be utilized to develop the formulation for improving the productivity of guar under drought-stress conditions.

Paenibacillus lentimorbus alleviates nutrient deficiency-induced stress in Zea mays by modulating root system architecture, auxin signaling, and metabolic pathways.

KEY MESSAGE: Paenibacillus lentimorbus reprograms auxin signaling and metabolic pathways for modulating root system architecture to mitigate nutrient deficiency in maize crops. The arable land across the world is having deficiency and disproportionate nutrients, limiting crop productivity. In this study, the potential of plant growth-promoting rhizobacteria (PGPR) viz., Pseudomonas putida, Paenibacillus lentimorbus, and their consortium was explored for growth promotion in maize (Zea mays) under nutrient-deficient conditions. PGPR inoculation improved the overall health of plants under nutrient-deficient conditions. The PGPR inoculation significantly improved the root system architecture and also induced changes in root cortical aerenchyma. Based on plant growth and physiological parameters inoculation with P. lentimorbus performed better as compared to P. putida, consortium, and uninoculated control. Furthermore, expression of auxin signaling (rum1, rul1, lrp1, rtcs, rtcl) and root hair development (rth)-related genes modulated the root development process to improve nutrient acquisition and tolerance to nutrient-deficient conditions in P. lentimorbus inoculated maize plants. Further, GC-MS analysis indicated the involvement of metabolites including carbohydrates and organic acids due to the interaction between maize roots and P. lentimorbus under nutrient-deficient conditions. These findings affirm that P. lentimorbus enhance overall plant growth by modulating the root system of maize to provide better tolerance to nutrient-deficient condition.

Bio-stimulants from medicinally and nutritionally significant plant extracts mitigate drought adversities in Zea mays through enhanced physiological, biochemical, and antioxidant activities.

Drought stress poses a substantial threat to global plant productivity amid increasing population and rising agricultural demand. To overcome this problem, the utilization of organic plant growth ingredients aligns with the emphasis on eco-friendly farming practices. Therefore, the present study aimed to assess the influence of 30 botanical extracts on seed germination, seedling vigor, and subsequent maize plant growth under normal and water deficit conditions. Specifically, eight extracts showed significant enhancement in agronomical parameters (ranging from ∼2 % to ∼ 183 %) and photosynthetic pigments (ranging from ∼21 % to âˆ¼ 195 %) of seedlings under drought conditions. Extended tests on maize in a greenhouse setting confirmed that the application of six extracts viz Moringa oleifera leaf (MLE), bark (MBE), Terminalia arjuna leaf (ALE), bark (ABE), Aegel marmelos leaf (BLE), and Phyllanthus niruri leaf (AmLE) improved plant growth and drought tolerance, as evident in improved physio-biochemical parameters. GC-MS analysis of the selected extracts unveiled a total of 51 bioactive compounds, including sugars, sugar alcohols, organic acids, and amino acids, and might be playing pivotal roles in plant acclimatization to drought stress. In conclusion, MLE, MBE, BLE, and ABE extracts exhibit significant potential for enhancing seedling establishment and growth in maize under both normal and water deficit conditions.

Endophytic Alkalotolerant Plant Growth-Promoting Bacteria Render Maize (Zea mays L.) Growth Under Alkaline Stress.

This study investigates the role of bacterial endophytes from extreme alkaline environments in alleviating alkaline stress and plant development. Stressful environmental factors, such as soil acidity and alkalinity/sodicity, frequently affect plant development. In the present study, alkaline-tolerant endophytic strains were isolated from three plant species Saccharum munja, Calotropis procera, and Chenopodium album, and 15 out of the total of 48 isolates were selected for further examination of their abiotic stress tolerance. Molecular analysis based on 16S rRNA gene sequencing revealed strains from Enterobacter, Acinetobacter, Stenotrophomonas, Bacillus, Lysinibacillus, and Mammaliicoccus genera. Out of 15 isolates based on their quantitative PGP traits and abiotic stress tolerance, 6 were finally selected for greenhouse experiments. Under alkaline conditions, results demonstrated that the strains from the genera Enterobacter, Bacillus, Stenotrophomonas, and Lysinibacillus had beneficial effects on maize growth. These findings suggest that using a combination of bacteria with multiple plant growth-promoting attributes could be a sustainable approach to enhance agricultural yield, even in a challenging alkaline environment. The study concludes that the application of bacterial endophytes from plants growing in extremely alkaline environments might provide other plants with similar stress-tolerance abilities. The outcome of the study provides a basis for future exploration of the mechanisms underlying endophyte-induced stress tolerance.

Arsenic stress management through arsenite and arsenate-tolerant growth-promoting bacteria in rice.

Arsenic (As) contamination is a major problem affecting soil and groundwater in India, harming agricultural crops and human health. Plant growth-promoting rhizobacteria (PGPR) have emerged as promising agents for reducing As toxicity in plants. This study aimed to isolate and characterize As-tolerant PGPR from rice field soils with varying As levels in five districts of West Bengal, India. A total of 663 bacterial isolates were obtained from the different soil samples, and 10 bacterial strains were selected based on their arsenite (As-III) and arsenate (As-V) tolerant ability and multiple PGP traits, including phosphate solubilization, production of siderophore, indole acetic acid, biofilm formation, alginate, and exopolysaccharide. These isolates were identified by 16S rRNA gene sequencing analysis as Staphylococcus sp. (4), Niallia sp. (2), Priestia sp. (1), Bacillus sp. (1), Pseudomonas sp. (1), and Citricoccus sp. (1). Among the selected bacterial strains, Priestia flexa NBRI4As1 and Pseudomonas chengduensis NBRI12As1 demonstrated significant improvement in rice growth by alleviating arsenic stress under greenhouse conditions. Both strains were also able to modulate photosynthetic pigments, soluble sugar content, proline concentration, and defense enzyme activity. Reduction in As-V accumulation inoculated with NBRI4As1 was recorded highest by 53.02% and 31.48%, while As-III by NBRI12As1 38.84% and 35.98% in the roots and shoots of rice plants, respectively. Overall, this study can lead to developing efficient As-tolerant bacterial strains-based bioinoculant application packages for arsenic stress management in rice.

Ochrobactrum sp. NBRISH6 Inoculation Enhances Zea mays Productivity, Mitigating Soil Alkalinity and Plant Immune Response.

Intensifying sodic land characterized by high alkaline pH is an incipient environmental hazard-limiting agricultural potential. In this study, we investigated the effects of plant growth-promoting bacteria Ochrobactrum sp. strain NBRISH6 on the growth and physiology of maize (Zea mays L.) grown under alkaline stress at two soil pH levels. Additionally, we also studied the effects of NBRISH6 on soil fertility parameters. A greenhouse experiment was designed using two live soils (pH 8.2 and 10.2) in earthen pots using maize as a host. Results revealed a significant increase in plant growth and a decrease in defense enzymes in both soil types due to NBRISH6 inoculation as compared to non-treated control. Furthermore, activities of all soil enzymes along with bacterial diversity increased in NBRISH6 treatment under normal as well as stressed conditions. In addition, field evaluation of NBRISH6 inoculation using maize was carried out under normal and alkaline conditions, which resulted in significant enhancement of all vegetative parameters as compared to respective controls. Therefore, the study suggested that Ochrobactrum sp. NBRISH6 can be used to develop a bioinoculant formulation to ameliorate abiotic stresses and enhanced crop productivity.

Correction to: Identification and validation of reference genes in vetiver (Chrysopogon zizanioides) root transcriptome.

[This corrects the article DOI: 10.1007/s12298-023-01315-7.].

The Efficacy of the Three Types of Plaque Control Methods During Fixed Orthodontic Treatment: A Randomized Controlled Trial.

BACKGROUND: When intraoral orthodontic devices are used, it becomes significantly more difficult to remove plaque effectively. Dentists and orthodontic specialists can come up with more effective preventive strategies while patients are undergoing fixed orthodontic work if they have a deeper understanding of the present scenario. In addition, individuals will become more aware of the importance of good dental hygiene habits as a result of this. OBJECTIVE: To assess and compare the effectiveness of a manual toothbrush, machine-driven toothbrush, and conventional mechanical toothbrush coupled with mouth rinse in removing plaque and maintaining gingival health in patients undergoing fixed orthodontic treatment. METHODS AND MATERIALS: In this research, a total of 222 individuals who met the eligibility and exclusion requirements were randomly selected and offered their written consent. There were a total of 74 participants for each of the three different categories. Category A used a physically driven toothbrush. Category B used a motorized toothbrush. Category C used a physically driven toothbrush together with mouthwash containing 0.2% chlorhexidine gluconate. All study participants were assessed at baseline, one-month follow-up, and two-month follow-up to document the preliminary information, including that of the modified papillary bleeding index (MPBI) by Muhlemann, plaque index (PI) introduced by Silness and Loe, and gingival index (GI) introduced by Loe and Silness. RESULTS: In this study, the mean PI scores at the one-month and two-month follow-ups were minimum in Category C, while it was maximum in Category A at the two-month follow-up. The mean GI scores at the two-month follow-up were minimum in Category C, while it was maximum in Category A at the two-month follow-up. The mean MPBI scores at the two-month follow-up were minimum in Category C, while it was maximum in Category A. It was observed that participants in this trial who only used a typical mechanical brush experienced an increase in PI and GI scores after one and two months of follow-up. At the one-month and two-month follow-ups, it was noted that the values of PI, GI, and MPBI significantly decreased in the study participants using automated toothbrushes as well as in study participants using manual toothbrushes in conjunction with chlorhexidine mouthwash as compared to baseline values. However, when the three categories were compared, it was found that the research participants utilizing both a manual toothbrush and 0.2% chlorhexidine experienced the highest decreases in PI, GI, and MPBI values. CONCLUSION: The reduction in the scores of PI, GI, and MPBI was maximum in orthodontic patients after two months when they apply manual toothbrushing along with 0.2% chlorhexidine.

Identification and validation of reference genes in vetiver (Chrysopogon zizanioides) root transcriptome.

Vetiver [Vetiveria zizanioides (L.) Roberty] is a perennial C-4 grass traditionally valued for its aromatic roots/root essential oil. Owing to its deep penetrating web-forming roots, the grass is now widely used across the globe for phytoremediation and the conservation of soil and water. This study has used the transcriptome data of vetiver roots in its two distinct geographic morphotypes (North Indian type A and South Indian type B) for reference gene(s) identification. Further, validation of reference genes using various abiotic stresses such as heat, cold, salt, and drought was carried out. The de novo assembly based on differential genes analysis gave 1,36,824 genes (PRJNA292937). Statistical tests like RefFinder, NormFinder, BestKeeper, geNorm, and Delta-Ct software were applied on 346 selected contigs. Eleven selected genes viz., GAPs, UBE2W, RP, OSCam2, MUB, RPS, Core histone 1, Core histone 2, SAMS, GRCWSP, PLDCP along with Actin were used for qRT-PCR analysis. Finally, the study identified the five best reference genes GAPs, OsCam2, MUB, Core histone 1, and SAMS along with Actin. The two optimal reference genes SAMS and Core histone 1 were identified with the help of qbase + software. The findings of the present analyses have value in the identification of suitable reference gene(s) in transcriptomic and molecular data analysis concerning various phenotypes related to abiotic stress and developmental aspects, as well as a quality control measure in gene expression experiments. Identifying reference genes in vetiver appears important as it allows for accurate normalization of gene expression data in qRT-PCR experiments. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01315-7.

Bacillus amyloliquefaciens modulate sugar metabolism to mitigate arsenic toxicity in Oryza sativa L. var Saryu-52.

In the current study, plant growth-promoting rhizobacterium Bacillus amyloliquefaciens SN13 (SN13) was evaluated for arsenic (As) toxicity amelioration potential under arsenate (AsV) and arsenite (AsIII) stress exposed to rice (Oryza sativa var Saryu-52) plants for 15 days. The PGPR-mediated alleviation of As toxicity was demonstrated by modulated measures such as proline, total soluble sugar, malondialdehyde content, enzymatic status, relative water content, and electrolytic leakage in treated rice seedlings under arsenic-stressed conditions as compared to the respective control. SN13 inoculation not only improved the agronomic traits but also modulated the micronutrient concentrations (Fe, Mo, Zn, Cu, and Co). The desirable results were obtained due to a significant decrease in the AsIII and AsV accumulation in the shoot (47 and 10 mg kg-1 dw), and the root (62 and 26 mg kg-1 dw) in B. amyloliquefaciens inoculated seedlings as compared to their uninoculated root (98 and 43 mg kg-1 dw) and shoot (57 and 12 mg kg-1 dw), respectively. Further, metabolome (GC-MS) analysis was performed to decipher the underlying PGPR-induced mechanisms under arsenic stress. A total of 67 distinct metabolites were identified, which influence the metabolic and physiological factors to modulate the As stress. The expression analysis of metabolism- and stress-responsive genes further proclaimed the involvement of SN13 through modulating the carbohydrate metabolism in rice seedlings, to enable improved growth and As stress tolerance.

Comprehensive illustration of transcriptomic and proteomic dataset for mitigation of arsenic toxicity in rice (Oryza sativa L.) by microbial consortium.

The present article represents the data for analysis of microbial consortium (P.putida+C.vulgaris) mediated amelioration of arsenic toxicity in rice plant. In the current study the transcriptome profiling of treated rice root and shoot was performed by illumina sequencing (Platform 2000). To process the reads and to analyse differential gene expression, Fastxtoolkit, NGSQCtoolkit, Bowtie 2 (version 2.1.0), Tophat program (version 2.0.8), Cufflinks and Cuffdiff programs were used. For Proteome profiling, total soluble proteins in shoot of rice plant among different treatments were extracted and separated by 2D poly acrylamide gel electrophoresis (PAGE) and then proteins were identified with the help of MALDI-TOF/TOF. In gel based method of protein identification, the isoelectric focusing machine (IPGphor system,Bio-Rad USA), gel unit (SDS-PAGE) and MALDI-TOF/TOF (4800 proteomic analyzer Applied Biosystem, USA) were used for successful separation and positive identification of proteins. To check the differential abundance of proteins among different treatments, PDQuest software was used for data analysis. For protein identification, Mascot search engine (http://www.matrixscience.com) using NCBIprot/SwissProt databases of rice was used. The analyzed data inferred comprehensive picture of key genes and their respective proteins involved in microbial consortium mediated improved plant growth and amelioration of As induced phyto-toxicity in rice. For the more comprehensive information of data, the related full-length article entitled "Microbial consortium mediated growth promotion and Arsenic reduction in Rice: An integrated transcriptome and proteome profiling" may be accessed.

Root system architecture, physiological analysis and dynamic transcriptomics unravel the drought-responsive traits in rice genotypes.

Drought is the major abiotic factors that limit crop productivity worldwide. To withstand stress conditions, plants alter numerous mechanisms for adaption and tolerance. Therefore, in the present study, 106 rice varieties were screened for drought tolerance phenotype via exposing different concentrations of polyethylene glycol 6000 (PEG) in the hydroponic nutrient medium at the time interval of 1, 3, and 7 days to evaluate the changes in their root system architecture. Further, based on root phenotype obtained after PEG-induced drought, two contrasting varieties drought-tolerant Heena and -sensitive Kiran were selected to study transcriptional and physiological alterations at the same stress durations. Physiological parameters (photosynthesis rate, stomatal conductance, transpiration), and non-enzymatic antioxidants (carotenoids, anthocyanins, total phenol content) production indicated better performance of Heena than Kiran. Comparatively higher accumulation of carotenoid and anthocyanin content and the increased photosynthetic rate was also observed in Heena. Root morphology (length, numbers of root hairs, seminal roots and adventitious roots) and anatomical data (lignin deposition, xylem area) enable tolerant variety Heena to better maintain membrane integrity and relative water content, which also contribute to comparatively higher biomass accumulation in Heena under drought. In transcriptome profiling, significant drought stress-associated differentially expressed genes (DEGs) were identified in both the varieties. A total of 1033 and 936 uniquely upregulated DEGs were found in Heena and Kiran respectively. The significant modulation of DEGs that were mainly associated with phytohormone signaling, stress-responsive genes (LEA, DREB), transcription factors (TFs) (AP2/ERF, MYB, WRKY, bHLH), and genes involved in photosynthesis and antioxidative mechanisms indicate better adaptive nature of Heena in stress tolerance. Additionally, the QTL-mapping analysis showed a very high number of DEGs associated with drought stress at AQHP069 QTL in Heena in comparison to Kiran which further distinguishes the drought-responsive traits at the chromosomal level in both the contrasting varieties. Overall, results support the higher capability of Heena over Kiran variety to induce numerous genes along with the development of better root architecture to endure drought stress.

Omics-Based Mechanistic Insight Into the Role of Bioengineered Nanoparticles for Biotic Stress Amelioration by Modulating Plant Metabolic Pathways.

Bioengineered silver nanoparticles can emerge as a facile approach to combat plant pathogen, reducing the use of pesticides in an eco-friendly manner. The plants' response during tripartite interaction of plant, pathogen, and nanoparticles remains largely unknown. This study demonstrated the use of bioengineered silver nanoparticles in combating black spot disease caused by necrotrophic fungus Alternaria brassicicola in Arabidopsis thaliana via foliar spray. The particles reduced disease severity by 70-80% at 5 µg/ml without showing phytotoxicity. It elicited plant immunity by a significant reduction in reactive oxygen species (ROS), decreases in stress enzymes by 0.6-19.8-fold, and emergence of autophagy. Comparative plant proteomics revealed 599 proteins expressed during the interaction, where 117 differential proteins were identified. Among different categories, proteins involved in bioenergy and metabolism were most abundant (44%), followed by proteins involved in plant defense (20%). Metabolic profiling by gas chromatography-mass spectroscopy yielded 39 metabolite derivatives in non-polar fraction and 25 in the polar fraction of plant extracts. It was observed that proteins involved in protein biogenesis and early plant defense were overexpressed to produce abundant antimicrobial metabolites and minimize ROS production. Bioengineered silver nanoparticles performed dual functions to combat pathogen attack by killing plant pathogen and eliciting immunity by altering plant defense proteome and metabolome.

Characterization of plant growth-promoting alkalotolerant Alcaligenes and Bacillus strains for mitigating the alkaline stress in Zea mays.

Intensification of sodic soil due to increasing pH is an emerging environmental issue. The present study aimed to isolate and characterise alkaline stress-tolerant and plant growth-promoting bacterial strains from moderately alkaline soil (pH 8-9), strongly alkaline soil (pH 9-10), and very strongly alkaline soil (> 10). Total 68 bacteria were isolated, and screened for multiple plant growth promoting (PGP) attributes. Out of total, 42 isolates demonstrating at least three plant growth promoting PGP traits selected for further assays. Then out of 42, 15 bacterial isolates were selected based on enhanced maize plant growth under greenhouse experiment, and 16S rRNA gene sequencing revealed Bacillus spp. as a dominant genus. Furthermore, based on improved seed germination percentage and biomass of maize (Zea mays L.) under alkaline stress conditions Alcaligenes sp. NBRI NB2.5, Bacillus sp. NBRI YE1.3, and Bacillus sp. NBRI YN4.4 bacterial strains were selected, and evaluated for growth-promotion and alkaline stress amelioration under greenhouse condition. Amongst the selected 3 plant growth promoting rhizobacterial (PGPR) strains, Bacillus sp. NBRI YN4.4 significantly improved the photosynthetic pigments and soluble sugar content, and decreased proline level in inoculated maize plants as compared to uninoculated control under stress conditions. Moreover, significantly enhanced soil enzymes such as dehydrogenase, alkaline phosphatase and betaglucosidase due to inoculation of Bacillus sp. NBRI YN4.4 in maize plants grown in alkaline soil attributes to its role in improving the soil health. Therefore, alkaline stress-tolerant PGPR NBRI YN4.4 can be useful for developing strategies for the reclamation of saline/sodic soils and improving the plant growth and soil health in sustainable manner.

Revealing the complexity of protein abundance in chickpea root under drought-stress using a comparative proteomics approach.

Global warming has reached an alarming situation, which led to a dangerous climatic condition. The irregular rainfalls and land degradation are the significant consequences of these climatic changes causing a decrease in crop productivity. The effect of drought and its tolerance mechanism, a comparative roots proteomic analysis of chickpea seedlings grown under hydroponic conditions for three weeks, performed at different time points using 2-Dimensional gel electrophoresis (2-DE). After PD-Quest analysis, 110 differentially expressed spots subjected to MALDI-TOF/TOF and 75 spots identified with a significant score. These identified proteins classified into eight categories based on their functional annotation. Proteins involved in carbon and energy metabolism comprised 23% of total identified proteins include mainly glyceraldehyde-3-phosphate dehydrogenase, malate dehydrogenase, transaldolase, and isocitrate dehydrogenase. Proteins related to stress response (heat-shock protein, CS domain protein, and chitinase 2-like) contributed 16% of total protein spots followed by 13% involved in protein metabolism (adenosine kinase 2, and protein disulfide isomerase). ROS metabolism contributed 13% (glutathione S-transferase, ascorbate peroxidase, and thioredoxin), and 9% for signal transduction (actin-101, and 14-3-3-like protein B). Five percent protein identified for secondary metabolism (cinnamoyl-CoA reductase-1 and chalcone-flavononeisomerase 2) and 7% for nitrogen (N) and amino acid metabolism (glutamine synthetase and homocysteine methyltransferase). The abundance of some proteins validated by using Western blotting and Real-Time-PCR. The detailed information for drought-responsive root protein(s) through comparative proteomics analysis can be utilized in the future for genetic improvement programs to develop drought-tolerant chickpea lines.

Drought tolerant Ochrobactrum sp. inoculation performs multiple roles in maintaining the homeostasis in Zea mays L. subjected to deficit water stress.

Plant growth-promoting rhizobacteria (PGPR) improve plant health under various biotic and abiotic stresses. However, the underlying mechanisms of the protective effects of PGPR in deficit water stress (WS) remain less explored. This study aimed to characterize the role of Ochrobactrum sp. NBRISH6 inoculation on maize (Zea mays "Maharaja") under WS conditions using multiple approaches such as physiological, anatomical, metabolic, and molecular. The effect of NBRISH6 inoculation using maize as a host plant was characterized under greenhouse conditions in deficit water stress. Results from this study demonstrated that NBRISH6 significantly lowered the expression of genes involved in the abscisic acid cycle, deficit water stress-response, osmotic stress, and antioxidant enzyme activity (superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, and polyphenol oxidase). Phytohormones, i.e. indole acetic acid (IAA) and salicylic acid (SA) levels, intercellular CO2 concentration, metabolites such as simple sugars, amino acids, aliphatic hydrocarbons, and the number of shrunken pith cells modulated in maize roots inoculated with NBRISH6. The NBRISH6 inoculation also improved the plant vegetative properties (root length, 33.80%; shoot length, 20.68%; root dry weight, 39.21%; shoot dry weight, 61.95%), shoot nutrients, xylem cells, root hairs, vapor pressure deficit (75%), intrinsic water-use efficiency (41.67%), photosynthesis rate (83.33%), and total chlorophyll (16.15%) as compared to the respective stress controls. This study provides valuable insights into mechanistic functions of PGPR in WS amelioration and promoting plant physiological response.

Betula utilis extract prolongs life expectancy, protects against amyloid-ß toxicity and reduces Alpha Synuclien in Caenorhabditis elegans via DAF-16 and SKN-1.

Betula utilis (BU), an important medicinal plant that grows in high altitudes of the Himalayan region, has been utilized traditionally due to it's antibacterial, hepatoprotective, and anti-tumor properties. Here, we demonstrated the longevity and amyloid-ß toxicity attenuating activity of B. utilis ethanolic extract (BUE) in Caenorhabditis elegans. Lifespan of the worms was observed under both the standard laboratory and stress (oxidative and thermal) conditions. Effect of BUE was also observed on the attenuation of age-dependent physiological parameters. Further, gene-specific mutants and green fluorescent protein (GFP)-tagged strains were used to investigate the molecular mechanism underlying the beneficial effects mediated by BUE supplementation. Our results showed that BUE (50 µg/ml) extended the mean lifespan of C. elegans by 35.99% and increased its survival under stress conditions. The BUE also reduced the levels of intracellular reactive oxygen species (ROS) by 22.47%. A delayed amyloid-ß induced paralyses was observed in CL4176 transgenic worms. Interestingly, the BUE supplementation was also able to reduce the α-synuclein aggregation in NL5901 transgenic strain. Gene-specific mutant studies suggested that the BUE-mediated lifespan extension was dependent on daf-16, hsf-1, and skn-1 but not on sir-2.1 gene. Furthermore, transgenic reporter gene expression assay showed that BUE treatment enhanced the expression of stress-protective genes such as sod-3 and gst-4. Present findings suggested that ROS scavenging activity, together with multiple longevity mechanisms, were involved in BUE-mediated lifespan extension. Thus, BUE might have potential to increase the lifespan and to attenuate neuro-related disease progression.

Bacillus amyloliquefaciens inoculation alters physiology of rice (Oryza sativa L. var. IR-36) through modulating carbohydrate metabolism to mitigate stress induced by nutrient starvation.

To avoid disproportionate usage of chemicals in agriculture, an alternative eco-friendly strategy is required to improve soil fertility, and enhance crop productivity. Therefore, the present study demonstrates the role of plant beneficial rhizobacteria viz., Paenibacillus lentimorbus B-30488 (B-30488), Bacillus amyloliquefaciens SN13 (SN13), and their consortium in rice (Oryza sativa L. var. IR-36) facing nutrient deprivation. Parameters such as proline, total soluble sugar, relative water content, electrolytic leakage and malondialdehyde content were modulated in control rice seedlings as compared to treated under nutrient starved conditions. Bacterial inoculation not only significantly improved the agronomic parameters but also concentrations, uptake and partitioning of macro-micro nutrients. To disclose PGPR induced mechanisms to low nutrient stress tolerance, GC-MS analysis was performed. Overall 43 differential metabolites were characterized. Proline, glutamine, linolenic acid, malic acid, ribitol, propanoic acid and serine were accumulated in seedlings exposed to nutrient starvation. In PGPR inoculated rice glucose, fructose, mannose, glucitol, oleic acid, gulonic acid, raffinose, inositol were accumulated that induce metabolic and physiological parameters to reduce the impact of stress. Based on results SN13 was selected for gene expression analysis of metabolism-related genes that further affirmed the ability of PGPR to modulate carbohydrate metabolism in rice seedlings under suboptimum nutrient level.

Transcriptional alterations reveal Bacillus amyloliquefaciens-rice cooperation under salt stress.

The Bacillus amyloliquefaciens-SN13 and model crop rice (Oryza sativa) were chosen to understand the complex regulatory networks that govern plant-PGPR interaction under salt stress. During stress, inoculation with SN13 significantly increased biomass, relative water content, proline and total soluble sugar in rice while decreased lipid peroxidation and electrolyte leakage. Extensive alterations in gene expression were also observed in rice root transcriptome under stress in the presence of SN13. Rhizobacteria induced changes in expression of a considerable number of photosynthesis, hormone, and stress-responsive genes, in addition to cell-wall and lipid metabolism-related genes under salt stress as compared to salt stress or SN13 inoculation alone, indicating its potential role in reducing the harmful effects of salinity. To validate RNA-seq data, qRT-PCR was performed for selected differentially expressed genes representing various functional categories including metabolism, regulation, stress-response, and transporters. Results indicate qualitative and quantitative differences between roots responses to SN13 under stressed and unstressed conditions. Functional expressions of OsNAM and OsGRAM in yeast showed enhanced tolerance to various abiotic stresses, indicating crucial SN13-rice interaction in imparting beneficial effects under stress. This is first detailed report on understanding molecular mechanism underlying beneficial plant-microbe interaction in any economically important model crop plant under abiotic stress.