Biology subjects

Chauhan, N. S.

Publications and source records attributed to Chauhan, N. S..

4 recordsLinked to original sources

bioRxiv2026

Agroforestry reshapes soil bacterial communities to enhance Ricinus communis oil quality and bioactivity over monocropping: comparative metagenomics and culture-dependent insights

An agroforestry (AF) system improves crop quality, ecosystem services, and microbial resilience, but its effects on oilseed bioactivity and soil microbiomes are still underexplored. This study compared AF and monocropping systems for castor (Ricinus communis L.) grown in Rajasthan, India, to evaluate plant productivity, seed oil composition, antimicrobial properties, and soil bacterial communities. AF enhanced seed morphology and germination. Castor oil from agroforestry had a 2.4-fold higher phenolic content, 2% more ricinoleic acid, and lower levels of oleic and linoleic acids compared to monocropping, confirmed by infrared spectroscopy and gas chromatography, along with increased expression of the RcDGAT2 gene involved in fatty acid biosynthesis. This led to improved antimicrobial activity against Bacillus mobilis and Pseudomonas fluorescens. Full-length 16S rRNA gene sequencing on the Nanopore platform identified 17 bacterial phyla in soil microbiomes, with Proteobacteria and Firmicutes as the dominant phyla. While alpha diversity was similar, AF soils showed distinct taxonomic shifts, enriching bacteria such as Alkalimonas, Aureimonas, Blastopirellula, Glutamicibacter, Rhizobium, Rhizomicrobium, and Rhodovulum, linked to nutrient cycling and plant growth promotion. Isolated rhizospheric/root endophytic Bacillus safensis and Enterobacter cloacae from AF castor exhibited plant growth-promoting traits via biochemical tests and whole-genome sequencing; their oil biosynthesis genes likely contribute to host oil quality by enhancing precursor supply and phenolic pathways. These isolates enhanced the growth of the model plant Arabidopsis thaliana. In summary, AF enhances the bioactivity of castor oil and microbial functions by modulating plant-soil-microbe interactions, thereby supporting sustainable crop quality and soil health.

microbiology↗

bioRxiv2025

A desert endophyte, Priestia megaterium SI1-IITJ, improves fluoride stress tolerance by reducing fluoride content of plant tissues and perturbing salt tolerance and defense genes of Arabidopsis thaliana

We isolated a fluoride (F-)-resistant bacterium, Priestia megaterium SI1-IITJ, from thse internal root tissues of several Thar Desert plants, Aerva javanica, Cyperus conglomeratus, Senna tora, and Tephrosia purpurea, tolerating up to 100 mM NaF. The root endophytic behavior of the isolate was confirmed by scanning electron microscopy. SI1-IITJ possesses plant growth-promoting properties, including auxin production (19.8 g mL-1), phosphate solubilization (index 3.64), ACC deaminase (0.54 mmol -ketobutyrate mL-1) and nitrate reductase (0.65 mol mL-1 nitrite) activities, revealed by biochemical tests and whole genome sequencing. SI1-IITJ extrudes F- from the cell, possibly through an F- efflux transporter, CrcB, identified in its genome. Significant growth improvements were observed in Arabidopsis thaliana under F- stress in hydroponics and soil culture upon coculture with SI1-IITJ, which improved the chlorophyll content by 1.6%, total nitrogen by 30.4%, and reduced reactive oxygen species by 48.9% and F- content by 63.9% in plant tissues. A differential gene expression analysis of A. thaliana by transcriptome sequencing indicated an unperturbed F- exporter, AtFEX1, but up-regulation of 55 genes regulating root meristem growth, cell wall modification, chlorophyll biosynthesis, Fe homeostasis, and high salt- and abiotic stress-responsive genes. On the other hand, 103 genes were down-regulated, suppressing systemic acquired resistance, plant defense, and H2O2 production. In conclusion, our results provide genomic insights into the mechanisms of F- toxicity alleviation and plant growth enhancement by a desert PGPR, highlighting Priestia megaterium SI1-IITJ as a potential biofertilizer for mitigating F- stress in plants.

plant biology↗

bioRxiv2025

Stenotrophomonas maltophilia promotes wheat growth by enhancing nutrient assimilation and rhizosphere microbiota modulation

BackgroundStenotrophomonas maltophilia has gained considerable attention for its biocontrol and biofertilizer potential in promoting plant growth. It could be employed to enhance wheat yield to ensure food security for the growing population. However, its biofertilizer potential in field conditions and its impact on wheat rhizosphere microbiota must be assessed before its employment in agriculture practices to increase wheat production. MethodsWe have assessed the role of Stenotrophomonas maltophilia on wheat seed germination, plant growth parameters, and crop yield in the field conditions. Additionally, wheat rhizosphere microbiota was explored to assess the impact of seed pretreatment with Stenotrophomonas maltophilia on the wheat rhizosphere microbiota. Results and DiscussionStenotrophomonas maltophilia strains BCM and BCM_F demonstrated superior antifungal activity, indicating their biocontrol potential. Seed pretreatment with these strains promoted nitrogen fixation and phosphate solubilization in the wheat rhizosphere showcasing biofertilizer potential. Uniquely identified OTUs in the rhizosphere microbiota of treated groups and microbial community dynamics, particularly at Feeks 3.0 and 6, indicated Stenotrophomonas maltophilia- induced microbiota restructuring. The abundance of Stenotrophomonas maltophilia 16S rRNA gene sequences at different Feeks treated with microbial indicates its stability across different plant growth stages. Their rhizospheric presence also impacted plant health indicators, including improved sugar and nitrite concentrations and significantly enhanced crop yield (P>0.05). Enhanced growth parameters and better crop yield in Stenotrophomonas maltophilia pre-inoculated seeds in field conditions indicated their potential to offer a sustainable alternative to enhance wheat production. ConclusionThe present study highlighted the biofertilizer and biocontrol potential of Stenotrophomonas maltophilia strains BCM and BCM_F in supporting sustainable agricultural practices.

microbiology↗

bioRxiv2025

Assessing wheat growth promotion potential of Delftia lacustris strain NSC through genomic and physiological characterization

BackgroundDelftia sp. has gained considerable attention for its biocontrol and biofertilizer potential to promote the growth of crops such as Oryza sativa, Brassica campestris, and Solanum lycopersicum. However, Delftia sp. supporting wheat plants is yet to be explored. MethodsDelftia strain was cultured from wheat rhizosphere using different growth conditions. The biofertilizer potential of Delftia strain was assessed through physiological, biochemical, genomic, and field experiments. Results and DiscussionPhylogenetic and phylogenomic analysis confirmed taxonomic affiliation with Delftia lacustris. In vitro phosphate solubilization (0.325IU), nitrate reduction (0.401 IU), IAA production (0.485 IU), ACC deaminase activity (0.512 EU), siderophore synthesis properties, and strong antifungal activity against Fusarium oxysporum and Rhizoctonia solani indicated its potential as an effective biofertilizer and biocontrol agent. Drought stress tolerance (up to 40% PEG), metal stress tolerance, salt stress tolerance (up to 11.69% NaCl (w/v), 11.18% KCl (w/v), 4.24% LiCl (w/v)) indicated its survivability even in hostile conditions. Genes for phosphate solubilization (PhoR, PhoB, PhoU, PstABCD), nitrogen fixation (nifC, nifU), auxin production, siderophore biosynthesis, rhizosphere colonization and antifungal properties (chitinase, PhnZ) explains Delftia lacustris bioactivities. Significantly enhanced seed germination (93.33% {+/-} 0.23), seedling growth, and biomass (P <0.05), particularly under stress conditions, indicated plant growth promotion properties of the Delftia strain. Significantly improved plant growth and yield parameters (P=0.0001) in field experiments, highlighting its potential as a biofertilizer and biocontrol agent. ConclusionDelftia lacustris strain NSC1 exhibits multifaceted biofertilizer and biocontrol potential, promoting plant growth, suppressing pathogens, and enhancing stress resilience. Its eco-friendly properties and field efficacy make it a promising alternative to chemical fertilizers for sustainable wheat production.

microbiology↗