Browsing by Author "Sandhya Mishra"

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Antibacterial and biofilm inhibition activity of biofabricated silver nanoparticles against Xanthomonas oryzae pv. oryzae causing blight disease of rice instigates disease suppression
(Springer, 2020) Sandhya Mishra; Xiaodong Yang; Shatrupa Ray; Leonardo Fernandes Fraceto; H.B. Singh
Antimicrobial activity of silver nanoparticles (AgNPs) has been well documented in earlier studies. As their efficient role in combating phytopathogens has begun recently, there is a huge scope to explore their effectiveness in agriculture. Considering the strong antifungal activity of biosynthesized AgNPs (as reported in our previous study), our main aim is to elucidate their antibacterial activity against bacterial plant pathogens to authenticate their wide range of agricultural applications. The present manuscript highlights the potential role of biosynthesized AgNPs against Xanthomonas oryzae pv. oryzae (Xoo) causing disastrous sheath blight disease of rice worldwide. We observed strong antibacterial activity of biosynthesized AgNPs (size ~ 12 nm) against Xoo at 20, 30 and 50 µg/mL concentrations. The significant inhibitory impact of AgNPs on biofilm formation by Xoo was noted even at the lower dose of 5 µg/mL (p = 0.001). Maximum biofilm inhibition (p = 0.000) was caused at 50 µg/mL concentration of AgNPs in comparison to control. Furthermore, disease suppression by biosynthesized AgNPs was authenticated under greenhouse conditions. Foliar spray of AgNPs significantly reduced the blight symptoms in rice sheaths as shown by 9.25% DLA (% Diseased leaf area) as compared to 33.91% DLA in Xoo inoculated rice plants. Altogether, our data suggest that biosynthesized AgNPs based nanoformulation can be applied for successful management of blight disease of rice. In addition, the antibiofilm strategies instigated by AgNPs can be exploited against a wide range of bacterial phytopathogens. In light of rapidly emerging antibiotic-resistant microbial strains, the current work provides an alternate effective platform for the application of nanoformulation for augmenting sustainability in the agriculture. © 2020, Springer Nature B.V.
Biofabricated silver nanoparticles act as a strong fungicide against Bipolaris sorokiniana causing spot blotch disease in wheat
(Public Library of Science, 2014) Sandhya Mishra; Braj Raj Singh; Akanksha Singh; Chetan Keswani; Alim H. Naqvi; H.B. Singh
The present study is focused on the extracellular synthesis of silver nanoparticles (AgNPs) using culture supernatant of an agriculturally important bacterium, Serratia sp. BHU-S4 and demonstrates its effective application for the management of spot blotch disease in wheat. The biosynthesis of AgNPs by Serratia sp. BHU-S4 (denoted as bsAgNPs) was monitored by UV-visible spectrum that showed the surface plasmon resonance (SPR) peak at 410 nm, an important characteristic of AgNPs. Furthermore, the structural, morphological, elemental, functional and thermal characterization of bsAgNPs was carried out using the X-ray diffraction (XRD), electron and atomic microscopies, energy dispersive X-ray (EDAX) spectrometer, FTIR spectroscopy and thermogravimetric analyzer (TGA), respectively. The bsAgNPs were spherical in shape with size range of ∼10 to 20 nm. The XRD and EDAX analysis confirmed successful biosynthesis and crystalline nature of AgNPs. The bsAgNPs exhibited strong antifungal activity against Bipolaris sorokiniana, the spot blotch pathogen of wheat. Interestingly, 2, 4 and 10 m g/ml concentrations of bsAgNPs accounted for complete inhibition of conidial germination, whereas in the absence of bsAgNPs, conidial germination was 100%. A detached leaf bioassay revealed prominent conidial germination on wheat leaves infected with B. sorokiniana conidial suspension alone, while the germination of conidia was totally inhibited when the leaves were treated with bsAgNPs. The results were further authenticated under green house conditions, where application of bsAgNPs significantly reduced B. sorokiniana infection in wheat plants. Histochemical staining revealed a significant role of bsAgNPs treatment in inducing lignin deposition in vascular bundles. In summary, our findings represent the efficient application of bsAgNPs in plant disease management, indicating the exciting possibilities of nanofungicide employing agriculturally important bacteria. © 2014 Mishra et al.
Biosynthesized silver nanoparticles as a nanoweapon against phytopathogens: exploring their scope and potential in agriculture
(Springer Verlag, 2015) Sandhya Mishra; H.B. Singh
The beneficial use of silver nanoparticles (AgNPs) in agroecosystems is not fully explored with partial information available, of which most of the studies are limited to laboratory conditions and only few involve natural ecosystems. AgNPs, being the most popular metallic nanoparticles exhibiting antimicrobial property, are predominantly used for plant disease management. Owing to the ill hazards of chemically synthesized AgNPs, their biosynthesis using environment-friendly biomolecules is gaining noteworthy attention. In addition, considering the advantages of nanoformulations over biopesticides, there is no doubt that biosynthesized AgNP-based biopesticides could revolutionize the agricultural sector in the future. Though enhanced commercial use of AgNPs has generated biosafety issues in modern scenario but expecting their significant contribution towards agricultural sector, it is too early to predict the risk factor associated with their usage. To unveil the toxicity factor of AgNPs, we need to focus and understand the major interactions of AgNPs in agroecosytems. Hence, the present review highlights (i) the potential application of AgNPs in the agricultural sector particularly for plant disease management, (ii) significance of biosynthesized AgNPs using microbes and plants over their chemical synthesis, (iii) major interactions of AgNPs in agroecosystems (with soil, soil biota, and plants) with emphasis to deal with toxicity-determining factors, and (iv) identifying future research work holding promising applications of biosynthesized AgNPs in agroecosystems. © 2014, Springer-Verlag Berlin Heidelberg.
Creating a global database “Nanomaterials in the soil environment”: future need for the terrestrial ecosystem
(Joint Center on Global Change and Earth System Science of the University of Maryland and Beijing Normal University, 2019) Sandhya Mishra; Harikesh Bahadur Singh; Xiaodong Yang
The revolutionary nanotechnology has generated environment safety concerns due to accumulation and toxicity behavior of nanomaterials. Given the wide application of various nanomaterials in daily products of our life, their environmental release is exceedingly obvious. Moreover, soil is the major sink for nanomaterials after their intentional or inadvertent release into the environment. Enormous attempts have apparently been made to study the impact of nanomaterials in the soil environment. Besides that, our understanding is inadequate due to disparities among results and effects of nanomaterials ranging from lethal, sub-lethal, to non-toxic. Subsequently, interpreting the real potential of nanomaterials to affect the soil environment and associated ecological processes is a challenging task. The interactions of different nanomaterials within different soil environments are crucial to authenticate toxicity behavior. Correspondingly, a global perspective is required for a comprehensive understanding of the environmental impact of nanomaterials. Therefore, we propose the need for a global database of “Nanomaterials in the soil environment” based on the estimates of nanomaterials flow among the three major components, viz. soil, soil microbes, and plants. Since the soil ecosystem is the foundation for many ecological processes supporting aboveground plant community and humankind, there is a need for this global database to precisely address the environmental issues. We propose that the empirical data from this global database would be helpful in bridging the knowledge gaps in the right way. Moreover, through this challenging task, soil policy can be developed to regulate nanomaterials usage and to protect soil health and associated biodiversity. © 2019, The Joint Center on Global Change and Earth System Science of the University of Maryland and Beijing Normal University.
Deciphering the Pathogenic Behaviour of Phyto-Pathogens Using Molecular Tools
(Wiley Blackwell, 2014) H.B. Singh; Akansha Jain; Amrita Saxena; Akanksha Singh; Chetan Keswani; Birinchi Kumar Sarma; Sandhya Mishra
The early detection and identification of plant pathogens are an integral part of successful disease management. Rapid identification of a plant pathogen provides appropriate control measures that could be applied prior to further spread of the disease or its introduction. The classical approach to plant disease diagnosis at the preliminary stage involved identification by visual symptoms followed by laboratory identification using selective media and microscopy to identify the infecting pathogens. But the conventional methods are a relatively slow process and often require skilled taxonomists for reliable identification of the pathogens. Therefore, in the past decade, major focus has shifted to the development of rapid, accurate and low cost methods with application in plant pathogen diagnosis. These methods include enzyme-linked immunosorbant assay (ELISA), the use of monoclonal antibodies, and DNA and PCR-based technologies which increase the sensitivity of pathogen detection. Rapid diagnosis and on-site quantification of phytopathogens and mapping them at locations of high disease incidence would enable the timely forecast of the advent of disease and would enable the farmers, agricultural authorities and research institutions to perform various management practices to control the disease. The present chapter deals with recent advances in molecular methods developed to detect and identify the four major classes of plant pathogens:viz. bacteria, fungi, nematodes and virus. © 2014 by John Wiley & Sons, Ltd. All rights reserved.
Differential Reprogramming of Defense Network in Capsicum annum L. Plants Against Colletotrichum truncatum Infection by Phyllospheric and Rhizospheric Trichoderma Strains
(Springer, 2020) Amrita Saxena; Sandhya Mishra; Shatrupa Ray; Richa Raghuwanshi; Harikesh Bahadur Singh
Induction of defense response in host plants by the Trichoderma spp. has been attributed as one of the major mechanisms leading to inhibition of the pathogenic ingression. The present study sheds light on the mechanisms employed by the Trichoderma isolates, obtained from phyllosphere (BHUF4) and rhizosphere (T16A), to modulate the defense network of chili plant under Colletotrichum truncatum challenge. Plants treated with both the Trichoderma strains exhibited significant accumulation of phenols under C. truncatum challenge with maximum increment recorded for capsaicin (16.1-fold), ferulic acid (5.03-fold), quercetin (5.36-fold), salicylic acid (94.88-fold), and kaempeferol (6.22-fold). Phenol accumulation corresponded to the subsequent defense gene expression pattern. When compared to the pathogen-challenged control plants, enhanced expression of PR1, PIK1, CHI, GLU, Cdef, and SAR genes was recorded in the Trichoderma-treated plants acting as a biocontrol agent (BCA). The results of the present study suggest that to strengthen the defense pathways in the host plant, the mechanisms employed by Trichoderma isolates differ and depend upon their origin and site of application. While phyllospheric Trichoderma isolate (BHUF4) employed the systemic acquired resistance (SAR) pathway, the rhizospheric Trichoderma strain (T16A) used the induced systemic response (ISR) pathway for eliciting the defense response in the host plant under C. truncatum challenge. The study signifies how Trichoderma strains obtained from different origin and when applied at different sites in plant judiciously reprogram the defense network of the host plant to provide robust protection against phytopathogens. In the present case, overall protection is provided to the chili plants against the foliar or underground attack of C. truncatum. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
Electrodynamical coupling of earth's atmosphere and ionosphere: An overview
(Hindawi Limited, 2011) A.K. Singh; Devendraa Siingh; R.P. Singh; Sandhya Mishra
Electrical processes occurring in the atmosphere couple the atmosphere and ionosphere, because both DC and AC effects operate at the speed of light. The electrostatic and electromagnetic field changes in global electric circuit arise from thunderstorm, lightning discharges, and optical emissions in the mesosphere. The precipitation of magnetospheric electrons affects higher latitudes. The radioactive elements emitted during the earthquakes affect electron density and conductivity in the lower atmosphere. In the present paper, we have briefly reviewed our present understanding of how these events play a key role in energy transfer from the lower atmosphere to the ionosphere, which ultimately results in the Earth's atmosphere-ionosphere coupling. © 2011 A. K. Singh et al.
Evidence for positive response of soil bacterial community structure and functions to biosynthesized silver nanoparticles: An approach to conquer nanotoxicity?
(Academic Press, 2020) Sandhya Mishra; Xiaodong Yang; Harikesh Bahadur Singh
The environmental impacts of biosynthesized nanoparticles on the soil bacterial community assemblage and functions are not sufficiently understood. Given the broad application of silver nanoparticles (AgNPs), the present study aims to reveal the effects of biosynthesized AgNPs (~12 nm) on the soil bacterial community structure and functions. Specifically, we used a quantitative real-time PCR (qPCR) approach to quantify the relative abundance of bacterial taxon/group and representative functional genes (AOA, AOB, NirK, NirS, NosZ, and PhoD). Results showed high relative abundance of Actinobacteria (1.53 × 107, p = 0.000) followed by Alphaproteobacteria (1.18 × 106, p = 0.000) and Betaproteobacteria (2.01 × 106, p = 0.000) in the soil exposed to biosynthesized AgNPs (100 mg/kg soil) after 30 days of treatment. Bacteroidetes group was observed to be negatively affected by AgNPs treatment. In the case of functional genes abundance, more pronounced impact was observed after 30 days of application. The biosynthesized AgNPs treatment accounted for significant increase in the relative abundance of all targeted functional genes except NirS. We conclude that the biosynthesized AgNPs did not cause toxic effects on nitrifiers, denitrifiers and organic phosphorus metabolizing bacterial community. While AgNO3 caused higher toxicity in the soil bacterial community structure and function. Based on our findings, we propose two key research questions for further studies; (i) is there any adaptation strategy or silver resistance embraced by the soil microbial community? and (ii) are biosynthesized nanoparticles environmentally safe and do not pose any risk to the soil microbial community? There is a necessity to address these questions to predict the environmental safety of biosynthesized AgNPs and to apply appropriate soil management policies to avoid nanotoxicity. Since this study provides preliminary evidence for the positive response of the soil bacterial community structure and functions to biosynthesized AgNPs, additional investigations under different soil conditions with varying soil physico-chemical properties are required to authenticate their environmental impact. © 2019 Elsevier Ltd
Harnessing plant-microbe interactions for enhanced protection against phytopathogens
(Springer India, 2015) Sandhya Mishra; Akanksha Singh; Chetan Keswani; Amrita Saxena; B.K. Sarma; H.B. Singh
Beneficial plant-microbe interactions have utmost importance for enhancing plant growth, improving soil structure, and managing plant diseases. Not surprisingly, such mutual interactions, where plants provide nourishment to rhizospheric microbes and in return microbes help in facilitating plant growth and stress amelioration, actually lay the foundation of sustainable agriculture. To cope with the major challenge of pathogen attack, beneficial rhizospheric microbes have proven their efficacy by induced systemic resistance (ISR). Therefore, such microbes are increasingly used in the form of biofertilizers and biopesticides. Moreover, such plantmicrobe interactions elicit a range of defense- responsive activities in order to combat the pathogen challenge. The main microbes- mediated defense strategies adopted by plants include activation of antioxidant status of the plant by reprogramming defense-related enzymes, modulation of quorum sensing phenomenon, and activation of phenylpropanoid pathway leading to phenolics production, lignin deposition, and transgenerational defense response. In this chapter, we highlight the relevance of beneficial interactions between plant and microbes in enhancing plants’ innate immune system against pathogen attack. This review provides a better understanding of the recent advances and major outcome of positive plant-microbe interactions and linking their relevance to plant defense response. © 2015 Springer India. All rights reserved.
Identification and Quantification of Heterologous Compounds Parthenin and Organic Acids in Parthenium Hysterophorus L. Using HPLC-PDA-MS-MS
(Bellwether Publishing, Ltd., 2013) Abhishek Niranjan; Sandhya Mishra; Alok Lehri; Devindra V. Amla; Ram Sanmukh Upadhyay; Chandra Shekhar Nautiyal
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 2.5 μg mL-1 (coumaric acid) to 5.2 μ g mL-1 (parthenin) and recovery ranged between 90.9% to 97.3%. To the best of our knowledge this is the first report for the simultaneous separation of parthenin and organic acids. The method is applicable for screening of commercial crops, medicinal plants, and their products which might be mixed with P. hysterophorus during harvesting period. © 2013 Copyright Taylor and Francis Group, LLC.
Integrated approach of Agri-Nanotechnology: Challenges and future trends
(Frontiers Research Foundation, 2017) Sandhya Mishra; Chetan Keswani; P.C. Abhilash; Leonardo F. Fraceto; Harikesh Bahadur Singh
Nanotechnology representing a new frontier in modern agriculture is anticipated to become a major thrust in near future by offering potential applications. This integrating approach, i.e., agri-nanotechnology has great potential to cope with global challenges of food production/security, sustainability and climate change. However, despite the potential benefits of nanotechnology in agriculture so far, their relevance has not reached up to the field conditions. The elevating concerns about fate, transport, bioavailability, nanoparticles toxicity and inappropriateness of regulatory framework limit the complete acceptance and inclination to adopt nanotechnologies in agricultural sector. Moreover, the current research trends lack realistic approach that fail to attain comprehensive knowledge of risk assessment factors and further toxicity of nanoparticles toward agroecosystem components viz. plant, soil, soil microbiomes after their release into the environment. Hence in the present review we attempt to suggest certain key points to be addressed in the current and future agri-nanotechnology researches on the basis of recognized knowledge gaps with strong recommendation of incorporating biosynthesized nanoparticles to carry out analogous functions. In this perspective, the major points are as follows: (i) Mitigating risk assessment factors (responsible for fate, transport, behavior, bioavailability and toxicity) for alleviating the subsequent toxicity of nanoparticles. (ii) Optimizing permissible level of nanoparticles dose within the safety limits by performing dose dependent studies. (iii) Adopting realistic approach by designing the experiments in natural habitat and avoiding in vitro assays for accurate interpretation. (iv) Most importantly, translating environmental friendly and non-toxic biosynthesized nanoparticles from laboratory to field conditions for agricultural benefits. © 2017 Mishra, Keswani, Abhilash, Fraceto and Singh.
Modulation in phenolic root exudate profile of Abelmoschus esculentus expressing activation of defense pathway
(Elsevier GmbH, 2018) Shatrupa Ray; Sandhya Mishra; Kartikay Bisen; Surendra Singh; Birinchi Kumar Sarma; Harikesh Bahadur Singh
Phenolics play a key role in communication between plants and microbes in the rhizosphere. In this study, shikimic, gallic, fumaric, ferulic, vanillic acid and quercetin in root exudates of Abelmoschus esculentus act as chemoattractants of endophytic Alcaligenes faecalis strains, BHU 12, BHU 16 and BHU M7. In vitro chemotaxis assay showed that BHU 12 expressed highest chemotactic movement (CFU ∼50 × 1012) towards A.esculentus root exudates followed by BHU 16 and BHU M7 (CFU∼ 9 × 1012), thereby confirming their ability to colonize the host rhizoplane region. However, BHU 16 expressed highest biofilm formation ability followed by BHU 12 and BHU M7. Assessment of chemotactic and biofilm formation potential towards individual phenolic acids revealed BHU 12 to be maximally attracted towards 1 μM shikimic acid (2 × 1015) while BHU 16 towards 1 mM vanillic acid (6.5 × 1012) and BHU M7 towards 1 mM ferulic acid (3.5 × 1012), thereby confirming the phenolic acid components responsible for particularly attracting the endophytic isolates. Upon colonization, the endophytic isolates modified the phenolic profiles of root exudates in planta in a manner so as to plausibly attract more of the beneficial rhizospheric microbiota as well as self-fortification against pathogenic microbes. This hypothesis was verified by monitoring the changes in phenolic components of A. esculentus root exudate owing to S. rolfsii infection, a disastrous soil-borne pathogen. Thus, on the whole, the work provides intricate details of plant-endophyte interactions for biotic stress management through careful manipulation of root exudates, thereby aiding in sustainable agriculture. © 2017
Potential of biosynthesized silver nanoparticles using Stenotrophomonas sp. BHU-S7 (MTCC 5978) for management of soil-borne and foliar phytopathogens
(Nature Publishing Group, 2017) Sandhya Mishra; Braj Raj Singh; Alim H. Naqvi; H.B. Singh
Stenotrophomonas sp. is emerging as a popular microbe of global concern with various potential ecological roles. Biosynthesis of gold and silver nanoparticles (AgNPs) using this bacterial strain has shown promising applications in life sciences. However, there is no report on efficient agricultural applications of biosynthesized AgNPs using Stenotrophomonas sp. In this regard, successful biosynthesis of AgNPs using Stenotrophomonas sp. BHU-S7 (MTCC 5978) was monitored by Uv-visible spectrum showing surface plasmon resonance (SPR) peak at 440 nm. The biosynthesized AgNPs were spherical with an average mean size of ∼12 nm. The antifungal efficacy of biosynthesized AgNPs against foliar and soil-borne phytopathogens was observed. The inhibitory impact of AgNPs (2, 4, 10 μg/ml) on conidial germination was recorded under in vitro conditions. Interestingly, sclerotia of Sclerotium rolfsii exposed to AgNPs failed to germinate on PDA medium and in soil system. Moreover, AgNPs treatment successfully managed collar rot of chickpea caused by S. rolfsii under greenhouse conditions. The reduced sclerotia germination, phenolic acids induction, altered lignification and H2O2 production was observed to be the probable mechanisms providing protection to chickpea against S. rolfsii. Our data revealed that AgNPs treated plants are better equipped to cope with pathogen challenge pointing towards their robust applications in plant disease management. © 2017 The Author(s).
Pseudomonas putida NBRIC19 provides protection to neighboring plant diversity from invasive weed Parthenium hysterophorus L. by altering soil microbial community
(Polish Academy of Sciences, 2014) Sandhya Mishra; Puneet Singh Chauhan; Anil Kumar Goel; Ram Sanmukh Upadhyay; Chandra Shekhar Nautiyal
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. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Pseudomonas putida NBRIC19 provides protection to neighboring plant diversity from invasive weed Parthenium hysterophorus L. by altering soil microbial community
(2012) Sandhya Mishra; Puneet Singh Chauhan; Anil Kumar Goel; Ram Sanmukh Upadhyay; Chandra Shekhar Nautiyal
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 Pseudomonasputida 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 Commelinabenghalensis and Cynodondactylon. 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. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Remediation of heavy metal-contaminated agricultural soils using microbes
(Springer India, 2016) Braj Raj Singh; Akanksha Singh; Sandhya Mishra; Alim H. Naqvi; Harikesh Bahadur Singh
Heavy metals are widely spread and accumulated in soil due to various inappropriate human activities, because of which metal pollution in soil has become one of the most serious environmental problems today. In this chapter, various microbial remediation mechanisms to remediate heavy metal-contaminated soils have been described. Microbial remediation, an emerging cost-effective, renewable, nonintrusive and aesthetically pleasing technology, uses the remarkable ability of microbes to remove and transform heavy metals from contaminated soils. The very limited understanding pertaining to heavy metal removal and transformation is hindering its effective application. Due to its great potential as a viable alternative to conventional contaminated soil remediation techniques, microbial remediation is currently being looked upon as an exciting area of basic and applied research. © Springer India 2016.
Silver nanoparticles mediated altered gene expression of melanin biosynthesis genes in Bipolaris sorokiniana
(Elsevier GmbH, 2015) Sandhya Mishra; H.B. Singh
Melanin production in many fungal phytopathogens has been investigated to play direct or indirect role in pathogenesis. However, in Bipolaris sorokiniana, the spot blotch pathogen of wheat, much less is known about the role melanin play in pathogenesis. As an extension of our previous report, the present study aims to investigate the plausible association between melanin production and virulence factor in B. sorokiniana. In the previous study, we carried out analysis on the antifungal efficacy of biosynthesized silver nanoparticles (AgNPs) against B. sorokiniana. The present investigation revealed the gene expression analysis of melanin biosynthesis genes viz. polyketide synthase (PKS1) and scytalone dehydratase (SCD1) under the influence of AgNPs. The 0.05. mg/ml concentration of AgNPs yielded noticeable inhibition of B. sorokiniana growth, while 0.1. mg/ml concentration of AgNPs accounted for complete inhibition of pathogen growth. In addition, the semiquantitative RT-PCR analysis exhibited reduced expression of PKS1 and SCD1 under the influence of AgNPs treatment. Furthermore, the qRT-PCR demonstrated 6.47 and 1.808 fold significant decrease in the expression pattern of PKS1 and SCD1, respectively, in B. sorokiniana treated with AgNPs. The present study provides probable understanding of molecular events underlying the antifungal role of AgNPs against B. sorokiniana. © 2015 Elsevier GmbH.
Trichoderma harzianum-based novel formulations: potential applications for management of Next-Gen agricultural challenges
(John Wiley and Sons Ltd, 2018) Leonardo F Fraceto; Cintia R Maruyama; Mariana Guilger; Sandhya Mishra; Chetan Keswani; Harikesh Bahadur Singh; Renata de Lima
Fungi of the Trichoderma spp. genus, notably Trichoderma harzianum, are commonly used for biological management of deleterious seed- and soil-borne pathogens. The global biopesticides market is booming with a major share of various commercial formulations of T. harzianum. However, there are some major drawbacks associated with these commercial formulations including short shelf life, low on-field stability and irregular performance in different agro-climatic regions. For effectively resolving these issues, new strategies are urgently required for efficient management of pathogens. The present review provides an overview of the use of Trichoderma spp., with special emphasis on T. harzianum, and discusses future trends for biological control. Technologies are described for the microencapsulation of fungi and for the biogenic synthesis of nanoparticles, with the aim of improving the biological control of pathogens and contributing to sustainable agricultural practices. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry
Unraveling the efficient applications of secondary metabolites of various Trichoderma spp.
(2014) Chetan Keswani; Sandhya Mishra; Birinchi Kumar Sarma; Surya Pratap Singh; Harikesh Bahadur Singh
Recent shift in trends of agricultural practices from application of synthetic fertilizers and pesticides to organic farming has brought into focus the use of microorganisms that carryout analogous function. Trichoderma spp. is one of the most popular genera of fungi commercially available as a plant growth promoting fungus (PGPF) and biological control agent. Exploitation of the diverse nature of secondary metabolites produced by different species of Trichoderma augments their extensive utility in agriculture and related industries. As a result, Trichoderma has achieved significant success as a powerful biocontrol agent at global level. The endorsement of Trichoderma spp. by scientific community is based on the understanding of its mechanisms of action against a large set of fungal, bacterial and in certain cases viral infections. However, it is still an agnostic view that there could be any single major mode of operation, although it is argued that all mechanisms operate simultaneously in a synchronized fashion. The central idea behind this review article is to emphasize the potentiality of applications of target specific secondary metabolites of Trichoderma for controlling phytopathogens as a substitute of commercially available whole organism formulations. With the aim to this point, we have compiled an inclusive list of secondary metabolites produced by different species of Trichoderma and their applications in diverse areas with the major emphasis on agriculture. Outlining the importance and diverse activities of secondary metabolites of Trichoderma besides its relevance to agriculture would generate greater understanding of their other important and beneficial applications apart from target specific biopesticides. © 2013 Springer-Verlag Berlin Heidelberg.
Unravelling the beneficial role of microbial contributors in reducing the allelopathic effects of weeds
(2013) Sandhya Mishra; Ram Sanmukh Upadhyay; Chandra Shekhar Nautiyal
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. © 2013 Springer-Verlag Berlin Heidelberg.