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.

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.

Application of natural language processing techniques to identify off-label drug usage from various online health communities.

OBJECTIVE: Outcomes mentioned on online health communities (OHCs) by patients can serve as a source of evidence for off-label drug usage evaluation, but identifying these outcomes manually is tedious work. We have built a natural language processing model to identify off-label usage of drugs mentioned in these patient posts. MATERIALS AND METHODS: Single patient posts from 4 major OHCs were considered for this study. A text classification model was built to classify the posts as either relevant or not relevant based on patient experience. The relevant posts were passed through a spelling correction tool, CSpell, and then medications and indications from these posts were identified using cTAKES (clinical Text Analysis and Knowledge Extraction System), a named entity recognition tool. Drug and indication pairs were identified using a dependency parser. Finally, if the paired indication was not mentioned on the label of the drug approved by U.S. Food and Drug Administration, it was tagged as off-label use of that drug. RESULTS: Using this algorithm, we identified 289 off-label indications, achieving a recall of 76%. CONCLUSIONS: The method designed in this study identifies and extracts the semantic relationship between drugs and indications from demotic posts in OHCs. The results demonstrate the feasibility of using natural language processing techniques in identifying off-label drug usage across online health forums for a variety of drugs. Understanding patients' off-label use of drugs may be able to help manufacturers innovate to better address patients' needs and assist doctors' prescribing decisions.

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, ß-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.