Search

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.

Nutrients are the finite natural resources that are essential for productivity and development of rice and its deficiency causes compromised yield along with reduced immunity against several biotic and abiotic stresses. In this study, the potential of Trichoderma reesei has been investigated as a biofertilizer (BF) to ameliorate nutrient stress in different rice cultivars at physiological, biochemical and molecular levels. The results indicated that cultivar Heena is much more compatible with BF as compared to cultivar Kiran at 50% nutrient limiting condition. Enhancement in physiological attributes and photosynthetic pigments were observed in BF treated Heena seedlings. The localization of biofertilizer in treated roots was further validated by scanning electron micrographs. This result correlated well with the higher levels of Indole acetic acid and Gibberellic acid in biofertilizer treated rice. Similarly, the uptake of micro-nutrients such as Fe, Co, Cu and Mo was found to be 1.4-1.9 fold higher respectively in BF treated Heena seedlings under 50% nutrient deficient condition. Furthermore, different stress ameliorating enzymes Guaiacol peroxidase, Super oxide dismutase, Total Phenolic Content, Phenol Peroxidase, Phenylalanine ammonia lyase and Ascorbate peroxidase in Heena seedlings were also increased by 1.8, 1.4, 1.2, 2.4, 1.2, and 8.3-fold respectively, at 50% nutrient deficient condition. The up-regulation of different micro and macro-nutrients allocation and accumulation; metal tolerance related; auxin synthesis genes in BF treated Heena as compared to 50% nutrient deficient condition was further supported by our findings that the application of biofertilizer efficiently ameliorated the deficiency of nutrients in rice.

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.

Herein, we describe the enhanced antifungal activity of silver nanoparticles biosynthesized by cell free filtrate of Trichoderma viride (MTCC 5661) in comparison to chemically synthesized silver nanoparticles (CSNP) of similar shape and size. Biosynthesized silver nanoparticles (BSNP) enhanced the reduction in dry weight by 20 and 48.8% of fungal pathogens Fusarium oxysporum and Alternaria brassicicola respectively in comparison to their chemical counterparts (CSNP). Nitroblue tetrazolium and Propidium iodide staining demonstrated the higher generation of superoxide radicals lead to higher death in BSNP treated fungus in comparison to CSNP. Scanning electron microscopy of A. brassicicola revealed the osmotic imbalance and membrane disintegrity to be major cause for fungal cell death after treatment with BSNP. To gain an insight into the mechanistic aspect of enhanced fungal cell death after treatment of BSNP in comparison to CSNP, stress responses and real time PCR analysis was carried out with A. brassicicola. It revealed that generation of ROS, downregulation of antioxidant machinery and oxidative enzymes, disruption of osmotic balance and cellular integrity, and loss of virulence are the mechanisms employed by BSNP which establishes them as superior antifungal agent than their chemical counterparts. With increasing drug resistance and ubiquitous presence of fungal pathogens in plant kingdom, BSNP bears the candidature for new generation of antifungal agent.

The present study aims to explore the alternative way to improve the quality and productivity of rice grown under CO2 stress through an external supplement of Trichoderma as a biofertilizer (BF). The impact of BF-treated rice under elevated CO2 (eCO2) was examined by different plant growth parameters, physiological observations, scanning electron microscopy, microbial community profiling and expression levels of stress-related genes. The effect of eCO2 on percent change in yielding attributes of rice (Heena and Kiran) was found higher in control, whereas it was reduced in the presence of BF. Photosynthetic rate, stomatal conductance and transpiration rate were higher in BF-treated rice under eCO2 condition. SEM analysis of BF-treated roots exhibits an increase in the number of metaxylem along with its diameter with thicker and rigid sclerenchymatous cells. Expression analysis of stress-related genes showed an increase in their mRNA transcripts under eCO2 condition. A significant change in the microbial community was found in the rhizospheric region of Heena treated with BF under eCO2. The current study demonstrates the potential of BF in ameliorating the stress generated as a result of CO2 enrichment.

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.

Background Indian rivers are a major source of livelihood as river water is used for drinking, agriculture, and religious purposes to a large population. In this study, we report comparative microbial structures and functional potential of four major rivers of India, namely Ganga, Narmada, Cauvery, and Gomti. Comparative microbiome study of these geographically distinct rivers was performed using the samples collected from the source to the downstream sites of each river. We employed metagenomic approach to comprehensively determine the taxonomic and functional potential of river microbiome. Results In this study, we report the pollution influences on microbial composition and functional potential of four distantly located rivers. Results revealed significant microbial diversity in contaminated locations as compared to the upstream samples. A total number of 37 bacterial phyla were detected out of which Proteobacteria, Actinobacteria, Bacteroidetes, Planctomycetes, and Verrucomicrobia were abundant. Microbial diversity in respect to anthropogenic activities revealed the prevalence of Acidobacteria, Actinobacteria, Verrucomicrobia, Firmicutes, and Nitrospirae phyla, whereas a decline in Proteobacteria and Bacteroides. Virulent and temperate bacteriophages were found high in Ganga when compared to others. Interestingly, the abundance of bacteriophage decreased with increasing pollution load in the river Ganga, unlike in other rivers. The carbon utilization studies indicated a correlation with functional genes occurred in metal contaminated sites. Ganga water has relatively higher trace elements at pristine-upstream than in the Narmada and Cauvery, indicating its origin from Himalayan rocky mountains and also both Ganga and Cauvery rivers found to harbour a large number of metal resistance genes. Conclusion Our findings indicate a correlation between pollution and the microbiome composition. The insights obtained suggest the role of high abundance of microbial communities with implications for human health and demonstrate the functional capabilities contributed by the microbial communities. Among the four rivers studied, the distinctiveness of Ganga in comparison to others, particularly upstream of Ganga revealed a highly dynamic microbial structure. Bhagirathi and Alaknanda confluence to form Ganga, the microbiome revealed that Alaknanda has the foremost contribution to Ganga with respect to microbial community, bacteriophages, and the type of trace elements and heavy metals detected.

Despite the vast exploration of endophytic microbes for growth enhancement in various crops, knowledge about their impact on the production of therapeutically important secondary metabolites is scarce. In the current investigation, chitinolytic bacterial endophytes were isolated from selected medicinal plants and assessed for their mycolytic as well as plant growth promoting potentials. Among them the two most efficient bacterial endophytes namely Bacillus amyloliquefaciens (MPE20) and Pseudomonas fluorescens (MPE115) individually as well as in combination were able to modulate withanolide biosynthetic pathway and tolerance against Alternaria alternata in Withania somnifera. Interestingly, the expression level of withanolide biosynthetic pathway genes (3-hydroxy-3-methylglutaryl co-enzyme A reductase, 1-deoxy-D-xylulose-5-phosphate reductase, farnesyl di-phosphate synthase, squalene synthase, cytochrome p450, sterol desaturase, sterol Δ-7 reductase and sterol glycosyl transferases) were upregulated in plants treated with the microbial consortium under A. alternata stress. In addition, application of microbes not only augmented withaferin A, withanolide A and withanolide B content (1.52-1.96, 3.32-5.96 and 12.49-21.47 fold, respectively) during A. alternata pathogenicity but also strengthened host resistance via improvement in the photochemical efficiency, normalizing the oxidized and non-oxidized fraction, accelerating photochemical and non-photochemical quantum yield, and electron transport rate. Moreover, reduction in the passively dissipated energy of PSI and PSII in microbial combination treated plants corroborate well with the above findings. Altogether, the above finding highlights novel insights into the underlying mechanisms in application of endophytes and emphasizes their capability to accelerate biosynthesis of withanolides in W. somnifera under biotic stress caused by A. alternata.

Rice grown in arsenic (As) contaminated areas contributes to high dietary exposure of As inducing multiple adverse effects on human health. The As contamination and application of phosphate fertilizers during seedling stage creates a high P and As stress condition. The flooded paddy fields are also conducive for algal growth and microbial activity. The present study proposes potential role of microalgae, Chlorella vulgaris (CHL) and bacteria, Pseudomonas putida (RAR) on rice plant grown under excess As and phosphate (P) conditions. The results show synchronized interaction of CHL + RAR which, reduces As uptake through enhanced P:As and reduced As:biomass ratio by modulating P trafficking. Gene expression analysis of different phosphate transporters exhibited correlation with reduced As uptake and other essential metals. The balancing of reactive oxygen species (ROS), proline accumulation, hormone modulation, and As sequestration in microbial biomass were elucidated as possible mechanisms of As detoxification. The study concludes that RAR and CHL combination mitigates the As stress during P-enriched conditions in rice by: (i) reducing As availability, (ii) modulating the As uptake, and (iii) improving detoxification mechanism of the plant. The study will be important in assessing the role and applicability of P solubilizing biofertilizers in these conditions.

In recent years, due to the rise in food consumption, much of the attention has been focused to increase the yield of the agricultural crops which resulted in compromised nutritional quality. Efforts have to be undertaken to enhance the nutritional attributes of legumes, cereals and staple food crops by increasing amino acids and mineral content. In the present study, we evaluated a protoplast fusant (H. lixii MTCC 5659) for its ability to enhance nutritional value and defence activity in chickpea. Essential amino acids; methionine (9.82 mg kg−1 dw), cysteine (2.61 mg kg−1 dw), glycine (11.34 mg kg−1 dw), valine (9.26 mg kg−1 dw), and non-essential amino acids; aspartic acid (39.19 mg kg−1 dw) and serine (17.53 mg kg−1 dw) were significantly higher in seeds of fusant inoculated chickpea. Fusant significantly improved accumulation of mineral nutrients i.e. Cu (157.73 mg kg−1 dw), Co (0.06 mg kg−1 dw), Ni (1.85 mg kg−1 dw), Zn (157.73 mg kg−1 dw) and S (16.29 mg kg−1 dw) in seeds. Biocontrol and defence activities of chickpea increased from 20 to 35% in fusant inoculated plants suggesting its potential to ameliorate biotic stress. To the best of our knowledge, this is the first report of an increase in amino acids and mineral content of chickpea by fusant inoculation.

Toxic metalloids including arsenic (As) can neither be eliminated nor destroyed from environment; however, they can be converted from toxic to less/non-toxic forms. The form of As species and their concentration determines its toxicity in plants. Therefore, the microbe mediated biotransformation of As is crucial for its plant uptake and toxicity. In the present study the role of As tolerant Trichoderma in modulating As toxicity in chickpea plants was explored. Chickpea plants grown in arsenate spiked soil under green house conditions were inoculated with two plant growth promoting Trichoderma strains, M-35 (As tolerant) and PPLF-28 (As sensitive). Total As concentration in chickpea tissue was comparable in both the Trichoderma treatments, however, differences in levels of organic and inorganic As (iAs) species were observed. The shift in iAs to organic As species ratio in tolerant Trichoderma treatment correlated with enhanced plant growth and nutrient content. Arsenic stress amelioration in tolerant Trichoderma treatment was also evident through rhizospheric microbial community and anatomical studies of the stem morphology. Down regulation of abiotic stress responsive genes (MIPS, PGIP, CGG) in tolerant Trichoderma + As treatment as compared to As alone and sensitive Trichoderma + As treatment also revealed that tolerant strain enhanced the plant's potential to cope with As stress as compared to sensitive one. Considering the bioremediation and plant growth promotion potential, the tolerant Trichoderma may appear promising for its utilization in As affected fields for enhancing agricultural productivity.

Impact of elevated CO2 (free air CO2 enrichment) was studied on wheat (Triticum aestivum L. var Kundan) growth, yield and proteome. Elevated CO2 significantly impacted both underground (+24%) and aboveground (+15%) biomass. Grain weight/plant and harvest index were increased by 35% and 11.4%, respectively under high CO2. On the other hand, seed protein content was decreased by 19% under CO2 enrichment while seed starch and soluble sugar contents were increased by 8% and 23%, respectively. Wheat leaf proteomics revealed that 50 proteins were showing differential expression. Twenty proteins were more abundant while 30 were less abundant. Thirty two proteins were identified by MALDI TOF TOF. More abundant proteins were related to defense, photosynthesis, energy metabolism etc. While less abundant proteins were related to glycolysis and gluconeogenesis. Wheat grain proteomics revealed that out of 49 differentially abundant proteins, 24 were more in abundance and 25 were less in abundance in wheat grains under eCO2 condition. Thirty three proteins were identified and functionally characterized. They were found to be involved mainly in carbon metabolism, storage, defence and proteolysis. Gluten proteins are the major component of wheat storage proteins. Our results showed that both high and low molecular weight glutenins were more in eCO2 wheat seeds while there was no change in gliadin evels. This might alter wheat dough strength. Concentration of grain Cr and As was increased at eCO2 while that of Fe, Cu, Zn and Se were found to be decreased. Dynamics of carbon utilization and metabolic abilities of soil microbes under eCO2 were significantly altered. Our study showed that altered wheat seed composition is cause for concern vis-a-vis nutrition and health and for industries which may have implications for agriculturally dominated country like India.

A simple and facile way of using biogenic silver nanoparticles (BSNP) (10–20 nm) was developed for wound healing acceleration and suppression of wound infections. The BSNP were formulated in an ointment base, and the study to accelerate the wound healing process was conducted in a rat. The pH of the BSNP ointment, pH 6.8 ± 0.5, lies in normal pH range of the human skin, with good spreadability and diffusibility. The wound closure rate, as a percentage, was highest at day 3 for a BSNP ointment-treated wound at 22.77 ± 1.60%, while in an untreated control the rate was 10.99 ± 1.74%, for Betadine 14.73 ± 2.36% and for Soframycin 18.55 ± 1.37%, compared with day 0. A similar pattern of wound closure rate was found at days 7 and 11. The antibacterial activity of BSNP was evaluated against wound-infection-causing bacteria Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by the agar diffusion method. The total bacterial counts in the wound area were enumerated by the colony forming unit method. The lowest number of bacterial counts was found in the BSNP-treated wound compared with the other groups. BSNP treatment at 7.5% concentration enhanced migration of fibroblasts in a scratch assay. These findings reveal BSNP as an efficient contrivance for wound healing acceleration and as an eco-friendly alternative therapeutic antimicrobial agent.

Betelvine is prone to several fungal diseases including leaf spots, foot and root rot caused by Fusarium spp. due to humid conditions prevailing in fields. In the present study, a potent antagonistic bacterial endophyte and a virulent fungal pathogen were selected after rigorous screening of isolates from different betelvine varieties to provide an efficient biocontrol strategy in cultivation of betelvine. Wild varieties of crops are a rich source of untapped endophytes. Of the four betelvine varieties used for isolations and screening, the wild variety was richest in endophytic populations. Using 16S rRNA sequencing, the selected antagonist was identified as Bacillus sp. (NBRI-W9). The pathogen, virulent against cultivated varieties, was identified as Fusarium sp. (NBRI-PMSF12) using ITS 1 and 2 region sequencing. Under in vitro and field conditions, NBRI-W9 was able to induce early rooting, provide plant growth promotion, increase leaf size and yield (leaf number) and provide biocontrol against the Fusarium sp. infection. NBRI-W9 treatments showed bacterial colonization on the leaf surface preferably in the vicinity of pearl glands and the collenchyma region in scanning electron microscope (SEM) studies. NBRI-W9 was observed to directly enter the leaf by degrading cell walls and colonize the subcellular layers. SEM analysis showed direct confrontation of NBRI-W9 with Fusarium on the leaf surface and in the collenchyma region as one of the probable modes of biocontrol.

A rapid and reliable method was developed and validated for determining betulin and betulinic acid in bark in Betula utilis by high-resolution magic angle spinning 1H nuclear magnetic resonance (HR-MAS NMR) spectroscopy. HR-MAS NMR spectroscopy clearly distinguished the resonances of betulin and betulinic acid in the bark of all accessions of B. utilis. The concentrations of betulin and betulinic acid were calculated and added to the spectra. The determination of the targeted metabolites in chloroform extract of bark of each accession of B. utilis was performed by high-performance liquid chromatography (HPLC). Quantitatively, betulin was present at higher concentrations than betulinic acid in all accessions. The HR-MAS NMR and HPLC results showed that betulin and betulinic acid varied significantly among accessions of B. utilis. Principal component analysis of the NMR and HPLC results provided classification into three metabolic groups in which the betulin concentration was high, moderate, or low....

The deterioration of water quality of river Ganga is a huge concern for Govt. of India. Apart from various pollution sources, the religious and ritualistic activities also have a good share in deteriorating Ganga water quality. Thus, the aim of the present study was to evaluate the changes in physico-chemical properties, microbial diversity and role of bacteriophages in controlling bacterial population of Ganga water during mass ritualistic bathing on the occasion of Maha-Kumbh in 2013. The BOD, COD, hardness, TDS and level of various ions significantly increased, while DO decreased in Ganga water during Maha-Kumbh. Ganga water was more affluent in trace elements than Yamuna and their levels further increased during Maha-Kumbh, which was correlated with decreased level of trace elements in the sediment. The bacterial diversity and evenness were increased and correlated with the number of devotees taking a dip at various events. Despite enormous increase in bacterial diversity during mass ritualistic bathing, the core bacterial species found in pre-Kumbh Ganga water were present in all the samples taken during Kumbh and post-Kumbh. In addition, the alteration in bacterial population during mass bathing was well under 2 log units which can be considered negligible. The study of bacteriophages at different bathing events revealed that Ganga was richer with the presence of bacteriophages in comparison with Yamuna against seven common bacteria found during the Maha-Kumbh. These bacteriophages have played a role in controlling bacterial growth and thus preventing putrefaction of Ganga water. Further, the abundance of trace elements in Ganga water might also be a reason for suppression of bacterial growth. Thus, the current study showed that Ganga has characteristic water quality in terms of physico-chemical property and microbial diversity that might have a role in the reported self-cleansing property of Ganga; however, the increased pollution load has surpassed its self-cleansing properties. Since water has been celebrated in all cultures, the outcome of the current study will not only be useful for the policy maker of cleaning and conservation of Ganga but also for restoration of other polluted rivers all over the world.

Endophytes have been explored and found to perform an important role in plant health. However, their effects on the host physiological function and disease management remain elusive. The present study aimed to assess the potential effects of endophytes, singly as well as in combination, in Withania somnifera (L.) Dunal, on various physiological parameters and systemic defense mechanisms against Alternaria alternata . Seeds primed with the endophytic bacteria Bacillus amyloliquefaciens and Pseudomonas fluorescens individually and in combination demonstrated an enhanced vigor index and germination rate. Interestingly, plants treated with the two-microbe combination showed the lowest plant mortality rate (28%) under A. alternata stress. Physiological profiling of treated plants showed improved photosynthesis, respiration, transpiration, and stomatal conductance under pathogenic stress. Additionally, these endophytes not only augmented defense enzymes and antioxidant activity in treated plants but also enhanced the expression of salicylic acid- and jasmonic acid-responsive genes in the stressed plants. Reductions in reactive oxygen species (ROS) and reactive nitrogen species (RNS) along with enhanced callose deposition in host plant leaves corroborated well with the above findings. Altogether, the study provides novel insights into the underlying mechanisms behind the tripartite interaction of endophyte- A. alternata - W. somnifera and underscores their ability to boost plant health under pathogen stress. IMPORTANCE W. somnifera is well known for producing several medicinally important secondary metabolites. These secondary metabolites are required by various pharmaceutical sectors to produce life-saving drugs. However, the cultivation of W. somnifera faces severe challenge from leaf spot disease caused by A. alternata . To keep pace with the rising demand for this plant and considering its capacity for cultivation under field conditions, the present study was undertaken to develop approaches to enhance production of W. somnifera through intervention using endophytes. Application of bacterial endophytes not only suppresses the pathogenicity of A. alternata but also mitigates excessive ROS/RNS generation via enhanced physiological processes and antioxidant machinery. Expression profiling of plant defense-related genes further validates the efficacy of bacterial endophytes against leaf spot disease.

Arsenic (As) contamination of soil is a serious problem limiting the rice grain nutrients production. Aim of this study was to identify the low grain As and sufficient selenium (Se) accumulating cultivars which may be suitable for human consumption and cultivation in As prone areas. Field trials at As contaminated sites of West Bengal, India were conducted to assess total As, inorganic arsenic (iAs) and Se content in rice grains by using HPLC-ICP-MS. Over a period of two years, 89 rice cultivars were cultivated at three different sites in West Bengal (India) having variable soil-As level. Selenium and As content in rice grains of various cultivars revealed that the number of safe cultivars decreased with increasing soil As level and also showed negative corelation (R=-0.997 **) between grain As and Se accumulation. However, total As content showed a positive correlation (R=0.903 *) with grain iAs content, while Se content in rice grains was negatively affected by As uptake. Only ten cultivars viz., IET-4786, CN1646-5, CN1794-2, Dusmix-40, S. Sankar, IR-64, IET-19226, Nayanmoni, CN1643-3 and CN1646-2 accumulating low grain As had sufficient Se. Therefore, cultivation of these ten genotypes may reduce the risk of possible dietary human As exposure and thus may be recommended for the cultivation in As affected areas in India.

Thermoplastic-based materials are recalcitrant in nature, which extensive use affect environmental health. Here, we attempt to compare the response of indigenously produced bacterial consortium-I and consortium-II in degrading polyvinyl chloride (PVC). These consortia were developed by using different combination of bacterial strains of Pseudomonas otitidis, Bacillus cereus, and Acanthopleurobacter pedis from waste disposal sites of Northern India after their identification via 16S rDNA sequencing. The progressive degradation of PVC by consortia was examined via scanning electron microscopy, atomic force microscopy, UV-vis, FT-IR spectra, gel permeation chromatography, and differential scanning calorimetry analysis at different incubations and time intervals. The consortium-II was superior over consortium-I in degrading the PVC. Further, the carbon source utilization analysis revealed that the extensive use of consortia has not any effect on functional diversity of native soil microbes.

Trichoderma reesei is an industrially important fungi which also imparts stress tolerance and plant growth promotion in various crops. Arsenic (As) contamination of field soils is one of the challenging problems in agriculture, posing potential threats for both human health and the environment. Plants in association with microbes are a liable method to improve metal tolerance and enhance crop productivity. Chickpea (Cicer arietinum L.), is an important grain legume providing cheap source of protein in semi-arid regions including As affected areas. In this study we report the role of T. reesei NBRI 0716 (NBRI 0716) in supporting chickpea growth and improving soil quality in As simulated conditions. NBRI 0716 modulated the As speciation and its availability to improve grain yield and quality (amino acids and mineral content) in chickpea (C. arietinum L.) plants grown in As spiked soil (100 mg As kg(-1) soil). Arsenic accumulation and speciation results indicate that arsenate [As(V)] was the dominant species in chickpea seeds and rhizosphere soil. The Trichoderma reduced total grain inorganic As (Asi) by 66% and enhanced dimethylarsonic acid (DMA) and monomethylarsinic acid (MMA) content of seed and rhizosphere soil. The results indicate a probable role of NBRI 0716 in As methylation as the possible mechanism for maneuvering As stress in chickpea. Analysis of functional diversity using carbon source utilization (Biolog) showed significant difference in diversity and evenness indices among the soil microbial rhizosphere communities. Microbial diversity loss caused by As were prevented in the presence of Trichoderma NBRI 0716.

Different kidney bean lines (48) were evaluated for diversity in seed (physicochemical, hydration, textural and cooking) and flour (antioxidant, total phenols, minerals, protein and pasting) properties. All the lines showed significant differential accumulation of minerals i.e. Fe, Mn, Cu, Na, Zn, K, Mg and Ca. Mn content was correlated with L* and b* values while Ca and Mg contents were correlated antioxidant potential relative to the phenolic content. Antioxidant activity (AOA) was measured using 2,2-diphenylpicrylhydrazine (DPPH) antioxidant assay and total phenolic content (TPC) was measured using Folin–Ciocalteu assay. AOA and TPC ranged from 2.14 to 94.24% of DPPH inhibition and 0.07 to 7.10 mg GAE/g, respectively. Light grain lines with lower L* had lower AOA and TPC as compared to the darker grain lines with higher L*. SDS-PAGE analysis showed the presence of 26 major polypeptides ranged from 12 to 137 kDa and among them, eight polypeptides were subjected to MALDI-TOF/MS analysis. These polypeptides were identified as phaseolin (alpha-type precursor) of 200 kDa, legumin (Phaseolus vulgaris) of 86 kDa, methionine synthase (Glycine max) of 84 kDa, 5-methyltetrahydropteroyltriglutamate-homocysteineS-methyltransferase, putative (Ricinus communis) of 80 kDa, chain A purple acid phosphatase of 59 kDa, IAA-protein conjugate (P. vulgaris) of 39 kDa and lectin (P. vulgaris) of 36 kDa. It has been observed that most of the lines which show the presence of 59 kDa protein also showed the presence of high activity of antioxidant.

In this study, the interaction of biosynthesized silver nanoparticles (BSNP) with native soil via plant transport was assessed in model pathosystem of Arabidopsis thaliana and Alternaria brassicicola. Foliar application of 5 μg/mL of BSNP reduced number of spores of fungi to 2.2 × 105 from 7 × 105, while numbers of lesions got reduced to 0.9/leaf in treated plants compared to 2.9/leaf in pathogen-infected plant without altering soil pH, electric conductivity, soil organic carbon and soil microbial biomass carbon. Soil enzyme activities including dehydrogenase, acid and alkaline phosphatase, urease, β-glucosidase and protease did not alter significantly in BSNP-treated plants compared to control plants. Application of BSNP did not alter the number of cultivable bacteria, fungi and actinomycetes. Effect of BSNP on uncultured bacterial diversity was measured by DGGE analysis which revealed similar banding pattern in all different treatments except in A. brassicicola-infected (AB) and A. brassicicola-infected plants treated with silver nanoparticles (AB + BSNP) after 120 days. Although AB-infected plants exhibited a decrease in bacterial diversity, treatment of AB + BSNP after 120 days demonstrated maximum bacterial diversity. McIntosh, Shannon, and Simpson diversity indices were calculated based on carbon source utilization pattern by BIOLOG analysis, revealing no significant difference among all treatments in different time intervals. BSNPs have the potential to act as strong antimicrobial agent for plant disease management without altering the native soil microflora.

Tomato suffers a huge loss every year because of early blight disease. This study focuses on efficient inhibition of Alternaria solani, the causative agent of early blight disease in tomato in vitro and in vivo. Foliar spray of 5 μg/mL of biosynthesized silver nanoparticles in A. solani infected plants resulted in significant increase of 32.58% in fresh weight and 23.52% in total chlorophyll content of tomato as compared to A. solani infected plants. A decrease of 48.57, 30, 39.59 and 28.57% was observed in fungal spore count, lipid peroxidation, proline content and superoxide dismutase respectively in infected tomato plants after treatment with synthesized silver nanoparticles as compared to A. solani infected plants. No significant variation in terms of soil pH, cultured population, carbon source utilization pattern and soil enzymes including dehydrogenase, urease, protenase and β-glucosidase was observed after foliar spray of nanoparticles. It was revealed that direct killing of pathogens, increased photosynthetic efficiencies, increased plant resistance and decrease in stress parameters and stress enzymes are the mechanisms employed by plants and nanoparticles simultaneously to combat the biotic stress. Biosynthesized silver nanoparticles bear the potential to revolutionize plant disease management, though the molecular aspects of increased resistance must be looked upon.

The major problem encountered during genetic manipulation of bacteria is the inability to get transformed because of their natural non-competency. In this study, to overcome this problem, a cost-effective method was developed by combining the properties of gold nanoparticles (GNPs) and the Yoshida effect. Various parameters, including GNP:plasmid ratio, pH and time, were optimized for stability of the GNP-plasmid conjugate. With non-competent Gram-negative cells, the efficiency ranged between 0.1 and 0.45 × 104 transformants μg-1, while the range was (0.02-0.2) × 104 transformants μg-1 with Gram-positive bacteria. GNPs can serve efficiently as a vehicle for better transformation in bacteria.

Biogenic synthesis of silver nanoparticles for enhanced antimicrobial activity has gained a lot of momentum making it an urgent need to search for a suitable biocandidate which could be utilized for efficient capping and shaping of silver nanoparticles with enhanced bactericidal activity utilizing its secondary metabolites. Current work illustrates the enhancement of antimicrobial efficacy of silver nanoparticles by reducing and modifying their surface with antimicrobial metabolites of cell free filtrate of Trichoderma viride (MTCC 5661) in comparison to citrate stabilized silver nanoparticles. Nanoparticles were characterized by visual observations, UV-visible spectroscopy, zetasizer, and transmission electron microscopy (TEM). Synthesized particles were monodispersed, spherical in shape and 10-20 nm in size. Presence of metabolites on surface of biosynthesized silver nanoparticles was observed by gas chromatography-mass spectroscopy (GC-MS), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The antimicrobial activity of both silver nanoparticles was tested against Shigella sonnei, Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) by growth inhibition curve analysis and colony formation unit assay. Further, it was noted that internalization of biosynthesized nanoparticles inside the bacterial cell was much higher as compared to citrate stabilized particles which in turn lead to higher production of reactive oxygen species. Increase in oxidative stress caused severe damage to bacterial membrane enhancing further uptake of particles and revoking other pathways for bacterial disintegration resulting in complete and rapid death of pathogens as evidenced by fluorescein diacetate/propidium iodide dual staining and TEM. Thus, study reveals that biologically synthesized silver nanoarchitecture coated with antimicrobial metabolites of T. viride was more potent than their chemical counterpart in killing of pathogenic bacteria.

The original version of this article unfortunately contained missing information at author’s affiliations. The affiliation address of the author’s Nishtha Mishra and Shipra Pandey should include “Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, U.P, India” as listed below.

Plant-growth-promoting rhizobacteria (PGPR) improve plant growth by altering the root architecture, although the mechanisms underlying this alteration have yet to be unravelled. Through microarray analysis of PGPR-treated rice roots, a large number of differentially regulated genes were identified. Ectopic expression of one of these genes, OsASR6 (ABA STRESS RIPENING6), had a remarkable effect on plant growth in Arabidopsis. Transgenic lines over-expressing OsASR6 had larger leaves, taller inflorescence bolts and greater numbers of siliques and seeds. The most prominent effect was observed in root growth, with the root biomass increasing four-fold compared with the shoot biomass increase of 1.7-fold. Transgenic OsASR6 over-expressing plants showed higher conductance, transpiration and photosynthesis rates, leading to an ˜30% higher seed yield compared with the control. Interestingly, OsASR6 expression led to alterations in the xylem structure, an increase in the xylem vessel size and altered lignification, which correlated with higher conductance. OsASR6 is activated by auxin and, in turn, increases auxin responses and root auxin sensitivity, as observed by the increased expression of auxin-responsive genes, such as SAUR32 and PINOID, and the key auxin transcription factor, ARF5. Collectively, these phenomena led to an increased root density. The effects of OsASR6 expression largely mimic the beneficial effects of PGPRs in rice, indicating that OsASR6 activation may be a key factor governing PGPR-mediated changes in rice. OsASR6 is a potential candidate for the manipulation of rice for improved productivity.

The field of allelopathy is one of the most fascinating but controversial processes in plant ecology that offers an exciting, interdisciplinary, complex, and challenging study. In spite of the established role of soil microbes in plant health, their role has also been consolidated in studies of allelopathy. Moreover, allelopathy can be better understood by incorporating soil microbial ecology that determines the relevance of allelopathy phenomenon. Therefore, while discussing the role of allelochemicals in plant-plant interactions, the dynamic nature of soil microbes should not be overlooked. The occurrence and toxicity of allelochemicals in soil depend on various factors, but the type of microflora in the surroundings plays a crucial role because it can interfere with its allelopathic nature. Such microbes could be of prime importance for biological control management of weeds reducing the cost and ill effects of chemical herbicides. Among microbes, our main focus is on bacteria--as they are dominant among other microbes and are being used for enhancing crop production for decades--and fungi. Hence, to refer to both bacteria and fungi, we have used the term microbes. This review discusses the beneficial role of microbes in reducing the allelopathic effects of weeds. The review is mainly focused on various functions of bacteria in (1) reducing allelopathic inhibition caused by weeds to reduce crop yield loss, (2) building inherent defense capacity in plants against allelopathic weed, and (3) deciphering beneficial rhizospheric process such as chemotaxis/biofilm, degradation of toxic allelochemicals, and induced gene expression.

Arsenic, a carcinogenic metalloid severely affects plant growth in contaminated areas. Present study shows role of Trichoderma reesei NBRI 0716 (NBRI 0716) in ameliorating arsenic (As) stress on chickpea under greenhouse conditions. Arsenic stress adversely affected seed germination (25%), chlorophyll content (44%) and almost eliminated nodule formation that were significantly restored on NBRI 0716 inoculation. It also restored stem anomalies like reduced trichome turgidity and density, deformation in collenchymatous and sclerenchymatous cells induced by As stress. Semi-quantitative RT-PCR of stress responsive genes showed differential expression of genes involved in synthesis of cell wall degrading enzymes, dormancy termination and abiotic stress. Upregulation of drought responsive genes (DRE, EREBP, T6PS, MIPS, and PGIP), enhanced proline content and shrunken cortex cells in the presence of As suggests that it creates water deficiency in plants and these responses were modulated by NBRI 0716 which provides a protective role. NBRI0716 mediated production of As reductase enzyme in chickpea and thus contributed in As metabolism. The study suggests a multifarious role of NBRI0716 in mediating stress tolerance in chickpea towards As.

Chickpea, a major pulse crop, is highly prone to a devastating wilt disease commonly caused by the complex interaction of soilborne fungal pathogens of the genus Fusarium, Rhizoctonia and Sclerotinia. These pathogens collectively cause both superficial and sunken lesions resulting in symptoms like wilting and yellowing causing plant losses at seedling stage and become a major limiting factor for its growth and yield. Earlier studies demonstrated the role of composted mixture in protection against soilborne pathogens. However, there is paucity of substantial evidence for the mechanism of protection. The present study predicts the probable mechanism of cow dung-mediated reduction of wilt in Cicer arietinum. Cow dung-coated seeds sown in presence of mixture of fungi (FCD) could reduce the activities of cell wall-degrading enzymes produced by plant roots in response to pathogens, which were otherwise higher in mixture of wilt complex fungi/pathogens (FUN) treatment. Reduction in transcript accumulation of related genes followed by histological studies showed intercellular fungal colonization in FUN treatment, whereas it was undetected in FCD. Results indicate that cow dung treatment of chickpea seeds reduces activities of the cell wall-degrading enzymes in a transcriptionally regulated manner, which in turn function as biocontrol measure for disease.

Parthenium hysterophorus L., is an obnoxious weed known for its environmental health hazards and medicinal uses. These characteristics are due to presence of sesquiterpene lactones and organic acids; therefore a rapid and sensitive analytical procedure using HPLC-PDA-MS-MS was developed and optimized for separation, identification, and quantification of parthenin and six organic acids. Separation and characterization of compounds was achieved on a RP-C18 column with 1% acetic acid in water (A) and acetonitrile (B) as a mobile phase at a flow rate of 0.6 mL min−1 and by matching their UV and mass spectra with reference compounds. Six organic acids (ferulic acid, 0.1 mg g−1 to coumaric acid, 13.6 mg g−1) and parthenin (27.4 mg g−1) were characterized within 26 minutes of chromatographic separation in plant extract. The calibration curves are linear with correlation coefficients from 0.985 to 0.998, limit of detection and quantification ranged between 1.0 µg mL−1 (anisic acid) to 2.2 µg mL−1 (parthenin) and ...

Several microbes with ability to promote plant growth and their products that can stimulate plant growth have been commercialized. This chapter is mainly restricted to the bacteria that are derived from plant rhizosphere and demonstrate their beneficial effects on the root. Such group of bacteria is generally designated as PGPR (plant growth promoting rhizobacteria). Beneficial effects of this group of rhizobacteria on plant growth can be demonstrated by both direct and indirect mechanisms. Various abiotic and biotic stresses negatively influence survival, biomass production, and crop yield. This chapter begins with the description of various abiotic and biotic stress factors affecting plant growth. Tolerance to these stresses is achieved by both physiological and molecular level adaptation. To exert the beneficial effects, bacteria must colonize the root surface efficiently as the roots are the first underground part of the plant system that experiences adverse conditions. Mechanisms of abiotic and biotic stress amelioration in the rhizosphere by PGPRs are subsequently described. PGPRs often have more than one mechanism for enhancing plant growth and experimental evidence suggests that the plant growth stimulation is the net result of multiple mechanisms of action that may be activated simultaneously. Thus, to fulfill the need of food production for ever-increasing global population under extreme environmental conditions or with limited sources, PGPRs are surely a major target to be developed for the improvement of tolerance to stresses.

Biosynthesis of nanoparticles has gained great attention in making the process cost-effective and eco-friendly, but there are limited reports which describe the interdependency of physical parameters for tailoring the dimension and geometry of nanoparticles during biological synthesis. In the present study, gold nanoparticles (GNPs) of various shapes and sizes were obtained by modulating different physical parameters using Trichoderma viride filtrate. The particles were characterized on the basis of visual observation, dynamic light scattering, UV-visible spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, and X ray diffraction. While the size varied from 2–500 nm, the shapes obtained were nanospheres, nanotriangles, nanopentagons, nanohexagons, and nanosheets. Changing the parameters such as pH, temperature, time, substrate, and culture filtrate concentration influenced the size and geometry of nanoparticles. Catalytic activity of the biosynthesized GNP was evaluated by UV-visible spectroscopy and confirmed by gas chromatography-mass spectrometric analysis for the conversion of 4-nitrophenol into 4-aminophenol which was strongly influenced by their structure and dimension. Common practices for biodegradation are traditional, expensive, require large amount of raw material, and time taking. Controlling shapes and sizes of nanoparticles could revolutionize the process of biodegradation that can remove all the hurdles in current scenario.

Spherical, rectangular, penta, and hexagonal silver nanoparticles of different dimensions were biosynthesized in an eco-friendly manner by biocontrol agent, Trichoderma viride by manipulating physical parameters, pH, temperature, and reaction time. The particles were characterized by UV–vis spectroscopy; Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Fourier Transform Infra-red Spectroscopy (FTIR). Shape and size dependent antimicrobial activity of nanoparticles against human pathogens was observed. Maximum inhibition was found with spherical nanoparticles (2–5 nm) showing 40, 51, 43, 53.9 and 55.8% against Shigella sonnei , Escherichia coli , Serratia marcescens , Staphylococcus . aureus and Pseudomonas aeruginosa respectively, where as pentagonal and hexagonal nanoparticles (50–100 nm) demonstrated 32, 41, 31, 42.84 and 42.80% of inhibition as compared to control. Nanoparticles of different geometry and dimension established enhanced antagonistic activity against pathogens with all the tested antibiotics. Excellent antimicrobial efficacy was obtained with spherical nanoparticles of 2–5 nm with ampicillin and penicillin. Shape and size played major role in enhancing antimicrobial potential of silver nanoparticles, both singly and synergistically with antibiotics which can be exploited to combat the spread of multidrug resistant pathogens.

Previous studies with Paenibacillus lentimorbus B-30488" (hereafter referred as B-30488), a plant growth promoting rhizobacteria (PGPR) isolated from cow's milk, revealed its capabilities to improve plant quality under normal and stress conditions. Present study investigates its potential as a biocontrol agent against an economically important virus, Cucumber mosaic virus (CMV), in Nicotiana tabacum cv. White Burley plants and delineates the physical, biophysical, biochemical and molecular perturbations due to the trilateral interactions of PGPR-host-CMV. Soil inoculation of B-30488 enhanced the plant vigor while significantly decreased the virulence and virus RNA accumulation by ~12 fold (91%) in systemic leaves of CMV infected tobacco plants as compared to the control ones. Histology of these leaves revealed the improved tissue's health and least aging signs in B-30488 inoculated tobacco plants, with or without CMV infection, and showed lesser intercellular spaces between collenchyma cells, reduced amount of xyloglucans and pectins in connecting primary cells, and higher polyphenol accumulation in hypodermis layer extending to collenchyma cells. B-30488 inoculation has favorably maneuvered the essential biophysical (ion leakage and photosynthetic efficiency) and biochemical (sugar, proline, chlorophyll, malondialdehyde, acid phosphatase and alkaline phosphatase) attributes of tobacco plants to positively regulate and release the virus stress. Moreover, activities of defense related enzymes (ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase and catalase) induced due to CMV-infection were ameliorated with inoculation of B-30488, suggesting systemic induced resistance mediated protection against CMV in tobacco. The quantitative RT-PCR analyses of the genes related to normal plant development, stress and pathogenesis also corroborate well with the biochemical data and revealed the regulation (either up or down) of these genes in favor of plant to combat the CMV mediated stress. These improvements led tobacco plant to produce more flowers and seeds with no negative impact on plant health. The present study may advocate the applicability of B-30488 for crop yield improvement in virus infested areas.

Members of genus Trichoderma are known worldwide for mycoparasitism. To gain a better insight into the organization and evolution of their genomes, we used an in silico approach to compare the occurrence, relative abundance and density of SSRs in Trichoderma atroviride, T. harzianum, T. reesei, and T. virens. Our analysis revealed that in all the four genome sequences studied, the occurrence, relative abundance, and density of microsatellites varied and was not influenced by genome sizes. The relative abundance and density of SSRs positively correlated with the G + C content of their genomes. The maximum frequency of SSRs was observed in the smallest genome of T. reesei whereas it was least in second smallest genome of T. atroviride. Among different classes of repeats, the tri-nucleotide repeats were abundant in all the genomes and accounts for ∼38%, whereas hexa-nuceotide repeats were the least (∼10.2%). Further evaluation of the conservation of motifs in the transcript sequences shows a 49.5% conservation among all the motifs. In order to study polymorphism in Trichoderma isolates, 12 polymorphic SSR markers were developed. Of the 12 markers, 6 markers are from T. atroviride and remaining 6 belong to T. harzianum. SSR markers were found to be more polymorphic from T. atroviride with an average polymorphism information content value of 0.745 in comparison with T. harzianum (0.615). Twelve polymorphic markers obtained in this study clearly demonstrate the utility of newly developed SSR markers in establishing genetic relationships among different isolates of Trichoderma.

Recent breakthroughs in rice arsenic (As) research demonstrate that As accumulation significantly affects trace nutrients in rice grain. In the present study we analyzed the amino acid (AA) profile of sixteen rice genotypes differing in grain As accumulation, grown at three sites with different soil As concentrations, in ascending order, Chinsurah

The ability of Paenibacillus lentimorbus B-30488 r (B-30488 r ) in reducing the early blight (EB) disease caused by Alternaria solani in tomato was assessed. Foliar application of the bacteria reduced the disease incidence by 45.3% as compared to control. In vitro studies indicated that B-30488 r effectively reduces the radial growth of A. solani in dual culture, and SEM studies demonstrated complete degradation of fungal hyphae on co-culture with B-30488 r . Both B-30488 r and A. solani exhibited high similarity in the nutrient utilization of carbon sources present in tomato tissues. Changes in gene expression studied using RT-PCR analyses indicate significant up-regulation of defense and growth-related genes in tomato plants treated with B-30488 r foliar spray and A. solani challenged plants pre-treated with B-30488 r foliar spray. Principal component analysis results indicated that tomato plants treated with A. solani affected microbial community structure and population of the rhizosphere as compared to B-30488 r . Results suggest that P. lentimorbus B-30488 r has a multiple mode of action for its biological control activity by inducing resistance in tomato plants, by degrading the pathogen cell wall, and by competing for similar sources of nutrients on the phyllosphere. Additionally, B-30488 r would not affect microbial populations on the rhizosphere of the tomato plants.

Amaranthus hypochondriacus L. infected with Ageratum enation virus (AEV) was investigated for identifying alteration in the anatomical structures, sap translocation and metabolomic variations using light microscopy, magnetic resonance imaging, NMR spectroscopy and GC–MS, respectively. Combination of GC–MS and NMR spectroscopy identified 68 polar and non-polar metabolites that were present in different levels in healthy and virus-infected A. hypochondriacus. Contrast of T1 and T2 weighted MR images showed significant differences in the spatial distribution of water, lipids and macromolecules indicating alterations in the cortical region and disruption of vascular bundles in virus-infected stem tissues. MRI observations are supported by light microscopic examination. Microscopic examination of AEV infected stem revealed severe hyperplasia with a considerable reduction in size of stem cells. The NMR spectroscopy and GC–MS analysis indicated that viral infection significantly affected the plant primary and secondary metabolism resulting in decreased glucose and sucrose content and increase in the concentration of β-sitosterol and stigmasterol. Higher accumulation of TCA cycle intermediates such as citric acid and malic acid in AEV infected plants indicated enhanced rate of respiratory metabolism. The viral stress significantly increases the concentration of erythritol and myo-inositol as compared to healthy ones. Lower concentration of glucose and sucrose in viral-infected stem tissues suggests decreased translocation of photosynthates in the plants. The results demonstrated potential of MRI, NMR spectroscopy and GC–MS for studying anatomical and metabolic variations in virus-infected plants.

Parthenium hysterophorus L. (Parthenium) is an invasive weed species which is spreading worldwide affecting natural ecological systems, biodiversity, crop production and human health. The present study was conducted to evaluate the potential of plant growth promoting Pseudomonas putida NBRIC19 in detoxifying the phytotoxic effect of Parthenium. Significant increase in C/N ratio, macronutrients, and micronutrients was observed in P. putida NBRIC19-treated soil. P. putida NBRIC19 treatment of the soil provided protection to plant communities in Parthenium invaded area, as the species diversity had increased in the treatment as compared to non-bacterized soil. P. putida NBRIC19 treatment besides Parthenium, also succeeded in controlling other weed species like Commelina benghalensis and Cynodon dactylon. In addition to this, the impact of Parthenium was also studied on functional microbial diversity based on carbon source utilization pattern. It was observed that P. putida NBRIC19 treatment of soil had shifted the microflora in such a manner that utilization of toxic allelochemicals increased to lessen their phytotoxic effect. Taken together, these results suggest that soil treatment with P. putida NBRIC19 may be used as a promising biological control measure for controlling the phytotoxic effect of Parthenium and in protecting ecosystem integrity of neighboring plants in Parthenium invaded areas.

Community level physiological profiling and pyrosequencing-based analysis of the V1-V2 16S rRNA gene region were used to characterize and compare microbial community structure, diversity, and bacterial phylogeny from soils of chemically cultivated land (CCL), organically cultivated land (OCL), and fallow grass land (FGL) for 16 years and were under three different land use types. The entire dataset comprised of 16,608 good-quality sequences (CCL, 6,379; OCL, 4,835; FGL, 5,394); among them 12,606 sequences could be classified in 15 known phylum. The most abundant phylum were Proteobacteria (29.8%), Acidobacteria (22.6%), Actinobacteria (11.1%), and Bacteroidetes (4.7%), while 24.3% of the sequences were from bacterial domain but could not be further classified to any known phylum. Proteobacteria, Bacteroidetes, and Gemmatimonadetes were found to be significantly abundant in OCL soil. On the contrary, Actinobacteria and Acidobacteria were significantly abundant in CCL and FGL, respectively. Our findings supported the view that organic compost amendment (OCL) activates diverse group of microorganisms as compared with conventionally used synthetic chemical fertilizers. Functional diversity and evenness based on carbon source utilization pattern was significantly higher in OCL as compared to CCL and FGL, suggesting an improvement in soil quality. This abundance of microbes possibly leads to the enhanced level of soil organic carbon, soil organic nitrogen, and microbial biomass in OCL and FGL soils as collated with CCL. This work increases our current understanding on the effect of long-term organic and chemical amendment applications on abundance, diversity, and composition of bacterial community inhabiting the soil for the prospects of agricultural yield and quantity of soil.

Aims: The aim of this study was to identify the gene responsible for degradation of toxic allelochemicals of Parthenium by generating Tn5-induced mutant of Pseudomonas putida NBRIC19. Furthermore, the study characterizes the mutant at physiological, biochemical and molecular level that helped in understanding the mechanisms of reducing the allelopathic inhibition of Parthenium by Ps. putida NBRIC19. Methods and Results: Tn5 mutant S-74.3 showing inability to degrade toxic allelochemicals was selected after screening 22 000 transconjugants. Tn5 flanking SucB gene (dihydrolipoamide succinyltransferase) of Ps. putida NBRIC19 was found to be responsible for the degradation of toxic allelochemicals that also affected biofilm formation, chemotaxis and alginate production under toxic environment of allelochemicals. Phenotypic microarray data revealed that the respiratory activity of Ps. putida NBRIC19 and S-74.3 differed on 47 substrates including amino acids, carboxylic acids, peptides and some chemical inhibitors. Conclusions: Study revealed that SucB gene regulates processes either directly or indirectly in Ps. putida NBRIC19, which on inactivation made the mutant less compatible for tolerating stress. Significance and Impact of the Study: This work provides the first evidence for a functional role of Ps. putida SucB gene in degradation of toxic allelochemicals of Parthenium that lead to reversal of plant growth inhibition by these toxic allelochemicals. The investigation also revealed interesting features about the involvement of microbes in plant–plant allelopathic interactions.

Plant growth promotion is a multigenic process under the influence of many factors; therefore an understanding of these processes and the functions regulated may have profound implications. Present study reports microarray analysis of Arabidopsis thaliana plants inoculated with Pseudomonas putida MTCC5279 (MTCC5279) which resulted in significant increase in growth traits as compared with non-inoculated control. The gene expression changes, represented by oligonucleotide array (24652 genes) have been studied to gain insight into MTCC5279 assisted plant growth promotion in Arabidopsis thaliana. MTCC5279 induced upregulated Arabidopsis thaliana genes were found to be involved in maintenance of genome integrity (At5g20850), growth hormone (At3g23890 and At4g36110), amino acid synthesis (At5g63890), abcissic acid (ABA) signaling and ethylene suppression (At2g29090, At5g17850), Ca+2 dependent signaling (At3g57530) and induction of induced systemic resistance (At2g46370, At2g44840). The genes At3g32920 and At2g15890 which are suggested to act early in petal, stamen and embryonic development are among the downregulated genes. We report for the first time MTCC5279 assisted repression of At3g32920, a putative DNA repair protein involved in recombination and DNA strand transfer in a process of rapid meiotic and mitotic division.