Influence of nanosilicon dioxide along with bioinoculants on Zea mays and its rhizospheric soil

Ellagic acid alleviates aluminum and/or drought stress through morpho-physiochemical adjustments and stress-related gene expression in Zea mays L

This study investigates the potential of ellagic acid (EA) to mitigate the effects of drought and aluminum (Al3+) stresses in maize by examining various morpho-physiochemical parameters and gene expressions. Maize (Zea mays L.) serves as a crucial global food source, but its growth and productivity are significantly hindered by drought and aluminum (Al3+) stresses, which lead to impaired root development, elevated levels of reactive oxygen species (ROS), diminished photosynthetic efficiency, and reduced water and mineral absorption. Recently, ellagic acid (EA), a polyphenolic compound with potent antioxidant properties, has been identified for its role in regulating plant growth and enhancing stress tolerance mechanisms. However, the specific mechanisms through which EA contributes to Al3+ and/or drought tolerance in plants remain largely unknown. The present study was conducted to examine the defensive role of EA (100 μg/mL) in some morpho-physiochemical parameters and the expression profiles of some stress-related genes (ZmCPK22, ZmXTH1, ZmHIPP4, ZmSGR, ZmpsbA, ZmAPX1, and ZmGST1) in drought (polyethylene glycol-6000 (PEG-6000), - 0.6 MPa) and aluminum chloride (AlCl3, 60 μM) stressed Zea mays Ada 523 grown in nutrient solution. Our results indicated that drought and aluminum chloride stresses affected root length, shoot height, H2O2 content, chlorophyll content (SPAD), electrolyte leakage (EL), and relative water content (RWC) of maize with several significant (P < 0.05) shifts up and down. Conversely, EA (100 μg/mL) treatment had a mitigating effect on these parameters. Moreover, EA also mitigated the antioxidant enzyme activities (superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX)), and regulated the expressions of aforementioned genes. These findings determined that EA treatment could efficiently improve the gene expressions and morpho-physiochemical parameters under drought and/or Al3+ stresses, thereby increasing the seedlings' adaptability to these stresses.

Unlocking the Potential of Nano-Enabled Precision Agriculture for Efficient and Sustainable Farming

Nanotechnology has attracted remarkable attention due to its unique features and potential uses in multiple domains. Nanotechnology is a novel strategy to boost production from agriculture along with superior efficiency, ecological security, biological safety, and monetary security. Modern farming processes increasingly rely on environmentally sustainable techniques, providing substitutes for conventional fertilizers and pesticides. The drawbacks inherent in traditional agriculture can be addressed with the implementation of nanotechnology. Nanotechnology can uplift the global economy, so it becomes essential to explore the application of nanoparticles in agriculture. In-depth descriptions of the microbial synthesis of nanoparticles, the site and mode of action of nanoparticles in living cells and plants, the synthesis of nano-fertilizers and their effects on nutrient enhancement, the alleviation of abiotic stresses and plant diseases, and the interplay of nanoparticles with the metabolic processes of both plants and microbes are featured in this review. The antimicrobial activity, ROS-induced toxicity to cells, genetic damage, and growth promotion of plants are among the most often described mechanisms of operation of nanoparticles. The size, shape, and dosage of nanoparticles determine their ability to respond. Nevertheless, the mode of action of nano-enabled agri-chemicals has not been fully elucidated. The information provided in our review paper serves as an essential viewpoint when assessing the constraints and potential applications of employing nanomaterials in place of traditional fertilizers.

Synergistic impact of nanomaterials and plant probiotics in agriculture: A tale of two-way strategy for long-term sustainability

Modern agriculture is primarily focused on the massive production of cereals and other food-based crops in a sustainable manner in order to fulfill the food demands of an ever-increasing global population. However, intensive agricultural practices, rampant use of agrochemicals, and other environmental factors result in soil fertility degradation, environmental pollution, disruption of soil biodiversity, pest resistance, and a decline in crop yields. Thus, experts are shifting their focus to other eco-friendly and safer methods of fertilization in order to ensure agricultural sustainability. Indeed, the importance of plant growth-promoting microorganisms, also determined as "plant probiotics (PPs)," has gained widespread recognition, and their usage as biofertilizers is being actively promoted as a means of mitigating the harmful effects of agrochemicals. As bio-elicitors, PPs promote plant growth and colonize soil or plant tissues when administered in soil, seeds, or plant surface and are used as an alternative means to avoid heavy use of agrochemicals. In the past few years, the use of nanotechnology has also brought a revolution in agriculture due to the application of various nanomaterials (NMs) or nano-based fertilizers to increase crop productivity. Given the beneficial properties of PPs and NMs, these two can be used in tandem to maximize benefits. However, the use of combinations of NMs and PPs, or their synergistic use, is in its infancy but has exhibited better crop-modulating effects in terms of improvement in crop productivity, mitigation of environmental stress (drought, salinity, etc.), restoration of soil fertility, and strengthening of the bioeconomy. In addition, a proper assessment of nanomaterials is necessary before their application, and a safer dose of NMs should be applicable without showing any toxic impact on the environment and soil microbial communities. The combo of NMs and PPs can also be encapsulated within a suitable carrier, and this method aids in the controlled and targeted delivery of entrapped components and also increases the shelf life of PPs. However, this review highlights the functional annotation of the combined impact of NMs and PPs on sustainable agricultural production in an eco-friendly manner.

Bionanotechnology in Agriculture: A One Health Approach

Healthy eating habits are one of the requirements for the health of society. In particular, in natura foods are increasingly encouraged, since they have a high concentration of nutrients. However, these foods are often grown in the presence of agrochemicals, such as fertilizers and pesticides. To increase crop productivity and achieve high vigor standards in less time, farmers make excessive use of agrochemicals that generate various economic, environmental, and clinical problems. In this way, bionanotechnology appears as an ally in developing technologies to improve planting conditions, ranging from the health of farmers and consumers to the production of new foods and functional foods. All these improvements are based on the better use of land use in synergy with the lowest generation of environmental impacts and the health of living beings, with a view to the study and production of technologies that take into account the concept of One Health in its processes and products. In this review article, we will address how caring for agriculture can directly influence the quality of the most desired foods in contemporary society, and how new alternatives based on nanotechnology can point to efficient and safe solutions for living beings on our planet.

Whole genome analysis for plant growth promotion profiling of Pantoea agglomerans CPHN2, a non-rhizobial nodule endophyte

Reduced agricultural production as well as issues like nutrient-depleted soils, eutrophication, and groundwater contamination have drawn attention to the use of endophyte-based bioformulations to restore soil fertility. Pantoea agglomerans CPHN2, a non-rhizobial nodule endophyte isolated from Cicer arietinum, exhibited a variety of plant growth-promoting traits. In this study, we used NextSeq500 technology to analyze whole-genome sequence information of this plant growth-promoting endophytic bacteria. The genome of P. agglomerans CPHN2 has a length of 4,839,532 bp and a G + C content of 55.2%. The whole genome comprises three different genomic fractions, comprising one circular chromosome and two circular plasmids. A comparative analysis between P. agglomerans CPHN2 and 10 genetically similar strains was performed using a bacterial pan-genome pipeline. All the predicted and annotated gene sequences for plant growth promotions (PGPs), such as phosphate solubilization, siderophore synthesis, nitrogen metabolism, and indole-3-acetic acid (IAA) of P. agglomerans CPHN2, were identified. The whole-genome analysis of P. agglomerans CPHN2 provides an insight into the mechanisms underlying PGP by endophytes and its potential applications as a biofertilizer.

Enhanced legume growth and adaptation to degraded estuarine soils using Pseudomonas sp. nodule endophytes

The joint estuary of Tinto and Odiel rivers (SW Spain) is one of the most degraded and polluted areas in the world and its recovery is mandatory. Legumes and their associated bacteria are recommended sustainable tools to fight against soils degradation and loss of fertility due to their known positive impacts on soils. The aim of this work was to isolate and characterize plant growth promoting nodule endophytes (PGPNE) from inside nodules of Medicago spp. naturally growing in the estuary of the Tinto and Odiel Rivers and evaluate their ability to promote legume adaptation in degraded soils. The best rhizobia and non-rhizobia among 33 endophytes were selected based on their plant growth promoting properties and bacterial enzymatic activities. These strains, identified as Pseudomonas sp. N4, Pseudomonas sp. N8, Ensifer sp. N10 and Ensifer sp. N12, were used for in vitro studies using Medicago sativa plants. The effects of individual or combined inoculation on seed germination, plant growth and nodulation were studied, both on plates and pots containing nutrient-poor soils and moderately contaminated with metals/loids from the estuary. In general, inoculation with combinations of rhizobia and Pseudomonas increased plant biomass (up to 1.5-fold) and nodules number (up to 2-fold) compared to single inoculation with rhizobia, ameliorating the physiological state of the plants and helping to regulate plant stress mechanisms. The greatest benefits were observed in plants inoculated with the consortium containing the four strains. In addition, combined inoculation with Ensifer and Pseudomonas increased As and metals accumulation in plant roots, without significant differences in shoot metal accumulation. These results suggest that PGPNE are useful biotools to promote legume growth and phytostabilization potential in nutrient-poor and/or metals contaminated estuarine soils.

Endophytes and their potential in biotic stress management and crop production

Biotic stress is caused by harmful microbes that prevent plants from growing normally and also having numerous negative effects on agriculture crops globally. Many biotic factors such as bacteria, fungi, virus, weeds, insects, and nematodes are the major constrains of stress that tends to increase the reactive oxygen species that affect the physiological and molecular functioning of plants and also led to the decrease in crop productivity. Bacterial and fungal endophytes are the solution to overcome the tasks faced with conventional farming, and these are environment friendly microbial commodities that colonize in plant tissues without causing any damage. Endophytes play an important role in host fitness, uptake of nutrients, synthesis of phytohormone and diminish the injury triggered by pathogens via antibiosis, production of lytic enzymes, secondary metabolites, and hormone activation. They are also reported to help plants in coping with biotic stress, improving crops and soil health, respectively. Therefore, usage of endophytes as biofertilizers and biocontrol agent have developed an eco-friendly substitute to destructive chemicals for plant development and also in mitigation of biotic stress. Thus, this review highlighted the potential role of endophytes as biofertilizers, biocontrol agent, and in mitigation of biotic stress for maintenance of plant development and soil health for sustainable agriculture.

Overview of biofertilizers in crop production and stress management for sustainable agriculture

With the increase in world population, the demography of humans is estimated to be exceeded and it has become a major challenge to provide an adequate amount of food, feed, and agricultural products majorly in developing countries. The use of chemical fertilizers causes the plant to grow efficiently and rapidly to meet the food demand. The drawbacks of using a higher quantity of chemical or synthetic fertilizers are environmental pollution, persistent changes in the soil ecology, physiochemical composition, decreasing agricultural productivity and cause several health hazards. Climatic factors are responsible for enhancing abiotic stress on crops, resulting in reduced agricultural productivity. There are various types of abiotic and biotic stress factors like soil salinity, drought, wind, improper temperature, heavy metals, waterlogging, and different weeds and phytopathogens like bacteria, viruses, fungi, and nematodes which attack plants, reducing crop productivity and quality. There is a shift toward the use of biofertilizers due to all these facts, which provide nutrition through natural processes like zinc, potassium and phosphorus solubilization, nitrogen fixation, production of hormones, siderophore, various hydrolytic enzymes and protect the plant from different plant pathogens and stress conditions. They provide the nutrition in adequate amount that is sufficient for healthy crop development to fulfill the demand of the increasing population worldwide, eco-friendly and economically convenient. This review will focus on biofertilizers and their mechanisms of action, role in crop productivity and in biotic/abiotic stress tolerance.

Nanobioremediation: A sustainable approach for the removal of toxic pollutants from the environment

In recent years, the proportion of organic and inorganic contaminants has increased rapidly due to growing human interference and represents a threat to ecosystems. The removal of these toxic pollutants from the environment is a difficult task. Physical, chemical and biological methods are implemented for the degradation of toxic pollutants from the environment. Among existing technologies, bioremediation in combination with nanotechnology is the most promising and cost-effective method for the removal of pollutants. Numerous studies have shown that exceptional characteristics of nanomaterials such as improved catalysis and adsorption properties as well as high reactivity have been subjects of great interest. There is an emerging trend of employing bacterial, fungal and algal cultures and their components, extracts or biomolecules as catalysts for the sustainable production of nanomaterials. They can serve as facilitators in the bioremediation of toxic compounds by immobilizing or inducing the synthesis of remediating microbial enzymes. Understanding the association between microorganisms, contaminants and nanoparticles (NPs) is of crucial importance. In this review, we focus on the removal of toxic pollutants using the cumulative effects of nanoparticles with microbial technology and their applications in different domains. Besides, we discuss how this novel nanobioremediation technique is significant and contributes towards sustainability.

Impact of nanophos in agriculture to improve functional bacterial community and crop productivity

BACKGROUND

Since the World's population is increasing, it's critical to boost agricultural productivity to meet the rising demand for food and reduce poverty. Fertilizers are widely used in traditional agricultural methods to improve crop yield, but they have a number of negative environmental consequences such as nutrient losses, decrease fertility and polluted water and air. Researchers have been focusing on alternative crop fertilizers mechanisms to address these issues in recent years and nanobiofertilizers have frequently been suggested. "Nanophos" is a biofertilizer and contains phosphate-solubilising bacteria that solubilises insoluble phosphate and makes it available to the plants for improved growth and productivity as well as maintain soil health. This study evaluated the impact of nanophos on the growth and development of maize plants and its rhizospheric microbial community such as NPK solubilising microbes, soil enzyme activities and soil protein under field condition after 20, 40 and 60 days in randomized block design.

RESULTS

Maize seeds treated with nanophos showed improvement in germination of seeds, plant height, number of leaves, photosynthetic pigments, total sugar and protein level over control. A higher activity of phenol, flavonoid, antioxidant activities and yield were noticed in nanophos treated plants over control. Positive shift in total bacterial count, nitrogen fixing bacteria, phosphate and potassium solubilizers were observed in the presence of nanophos as compared to control. Soil enzyme activities were significantly (P < 0.05) improved in treated soil and showed moderately correlation between treatments estimated using Spearman rank correlation test. Real time PCR and total soil protein content analysis showed enhanced microbial population in nanophos treated soil. Obtained results showed that nanophos improved the soil microbial population and thus improved the plant growth and productivity.

CONCLUSION

The study concluded a stimulating effect of nanophos on Zea mays health and productivity and indicates good response towards total bacterial, NPK solubilising bacteria, soil enzymes, soil protein which equally showed positive response towards soil nutrient status. It can be a potential way to boost soil nutrient use efficiency and can be a better alternative to fertilizers used in the agriculture.

Impact of nanochitosan and Bacillus spp. on health, productivity and defence response in Zea mays under field condition

The role of plant growth-promoting rhizobacteria along with nanochitosan on maize productivity remains unexplored. In the present study we report the effect of nanochitosan and PGPR on growth, productivity and mechanism(s) involved in defence response in Zea mays under field conditions. Application of nanochitosan (50 mg L^-1) along with plant growth-promoting rhizobacteria enhanced seed germination, plant height, root length, leaf area, fresh and dry weight of shoot and root, chlorophyll, carotenoids, total sugar and protein content upto 1.5-2 fold over control in maize after 60 days of the field experiment. Treated maize plants also showed enhanced level of defence-related biomolecules like phenolic compounds (103%), catalase (60.09%), peroxidase (81.57%) and superoxide dismutase (76.50%) over control. Level of phenols and sugar content in maize plants enhanced which was analysed by GC-MS (Gas chromatography-mass spectrometry). Significant increase in cob length, cob weight/plot, grain yield/plot and 100 grain weight was observed in treated maize plants over control. As per the results, the combination of nanochitosan and plant growth-promoting rhizobacteria was reported to improve the health and yield of maize. The interaction can be further studied in field trials for improvement in agriculture production.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02790-z.

Cultivable and metagenomic approach to study the combined impact of nanogypsum and Pseudomonas taiwanensis on maize plant health and its rhizospheric microbiome

In the present study we examined the effect of nanogypsum and Pseudomonas taiwanensis strain BCRC 17751on plant and soil health using conventional and metagenomics approaches. Soil physicochemical properties and agronomical parameters of maize plants were reported to be better when applied with nanogypsum and bacterial inoculum together. When compared to control a significant increase in total bacterial counts, nitrogen, phosphorus, potassium (NPK) solubilizing bacterial population and soil enzyme activities (fluorescein diacetate, alkaline phosphatase, dehydrogenase, β-glucosidase, arylesterase and amylase) was reported in treatments. The metagenomics studies revealed dominance of beneficial bacteria such as Proteobacteria, Bacteriodetes, Planctomycetes, Acidobacteria and Nitrospirae in treated soil. On the other hand some novel bacterial diversity was also reported in treated soil which was evident from presence of taxonomically unclassified sequences. Hence, it can be concluded that combined application of nanogypsum and Pseudomonas taiwanensis in maize help in improving the structure and function of soil which affects the plant health without causing any toxic effect. However, in situ validation of the prescribed treatment is required under field conditions on different crops in order to give maximum benefits to the farmers and the environment.

Bioinoculation using indigenous Bacillus spp. improves growth and yield of Zea mays under the influence of nanozeolite

Bio-inoculants play an important role for sustainable agriculture. Application of nanocompounds in the agriculture sector provides strength and is reported to enhance crop production but the combined effect of nanocompounds and plant growth-promoting rhizobacteria on plants has not been studied much. Therefore, the present study was planned to observe the effect of two plant growth promotory Bacillus spp. along with nanozeolite on maize under field conditions using a randomized block design. Combined treatment of nanozeolite and bio-inoculants promoted plant height, root length, fresh and dry weight of shoot and root, chlorophyll, carotenoids, total sugar, protein and phenol contents in maize significantly over control. Enhanced level of catalase, peroxidase, superoxide dismutase, phenols, alcohols and acid-esters in treated plants over control showed their role in stress management. An increase of 29.80% in maize productivity over control was reported in the combined treatment of Bacillus sp. and nanozeolite. Our results indicate that the application of bio-inoculants with nanozeolite showed a positive response on the health and productivity of maize plants. Hence, these may be used to enhance the productivity of different crops.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-020-02561-2.

Management of plant vigor and soil health using two agriusable nanocompounds and plant growth promotory rhizobacteria in Fenugreek

Application of nanocompounds and plant growth promoting rhizobacteria (PGPR) plays an important role in improving plant growth and soil health. In the present study, response of two PGPR (PS2-KX650178 and PS10-KX650179) along with nanozeolite and nanochitosan was studied on Fenugreek (Trigonella foenum-graecum), on the basis of physiological and biochemical parameters of soil and plant in pot experiment for 45 days. A significant increase (1.5-2 folds) in plant height, leaf number, leaf area and fresh weight over control was observed in Fenugreek plants when treated with nanocompounds and PGPR. Combined treatment also showed the highest level of total chlorophyll (3.27 mg g^-1), sugar (6.14 μg mg^-1 dry wt), soluble leaf protein (295.37 mg g^-1 fresh weight) and catalase activity (23.84 U g^-1 tissue) in Fenugreek plants. GC-MS analysis of plant metabolites revealed the abundance of phenols which are known to improve biotic/abiotic stresses in plants. Activity of Fluorescein Diacetate hydrolase enzyme was 2.5 times higher in the combined treatment of nanozeolite with PS10 than in control. An increase of 11% in alkaline phosphatase activity was observed in the same treatment with respect to control. The results obtained from the pot experiment clearly indicate that nanocompounds along with PGPR improved the growth of plants and soil health which suggest their benefits in agriculture practices to increase crop production.