Seed biopriming for sustainable agriculture and ecosystem restoration

The utilization of microbial inoculants in the realm of sustainable agricultural and ecosystem restoration has witnessed a surge in recent decades. This rise is largely attributed to advancements in our understanding of plant-microbe interactions, the urgency to reduce the dependence on agrochemicals and the growing societal demand for sustainable strategies in ecosystem management. However, despite the rapid growth of bio-inoculants sector, certain limitations persist concerning their efficacy and performance under the field condition. Here, we propose that seed biopriming, an effective microbial inoculant technique integrating both biological agents (the priming of beneficial microbes on seeds) and physiological aspects (hydration of seeds for improved metabolically activity), has a significant potential to mitigate these limitations. This method increases the protection of seeds against soil-borne pathogens and soil pollutants, such as salts and heavy metals, while promoting germination rate and uniformity, leading to overall improved primary productivity and soil health. Furthermore, we argue that a microbial coating on seeds can facilitate transgenerational associations of beneficial microbes, refine plant and soil microbiomes, and maintain soil legacies of beneficial microflora. This review article aims to improve our understanding of the seed biopriming approach as a potent and valuable tool in achieving sustainable agriculture and successful ecosystem restoration.

Multifarious Plant Growth-Promoting Rhizobacterium Enterobacter sp. CM94-Mediated Systemic Tolerance and Growth Promotion of Chickpea (Cicer arietinum L.) under Salinity Stress

BACKGROUND

Chickpea is one of the most important leguminous crops and its productivity is significantly affected by salinity stress. The use of ecofriendly, salt-tolerant, plant growth-promoting rhizobacteria (PGPR) as a bioinoculant can be very effective in mitigating salinity stress in crop plants. In the present study, we explored, characterized, and evaluated a potential PGPR isolate for improving chickpea growth under salt stress.

METHODS

A potential PGPR was isolated from rhizospheric soils of chickpea plants grown in the salt-affected area of eastern Uttar Pradesh, India. The isolate was screened for salt tolerance and characterized for its metabolic potential and different plant growth-promoting attributes. Further, the potential of the isolate to promote chickpea growth under different salt concentrations was determined by a greenhouse experiment.

RESULTS

A rhizobacteria isolate, CM94, which could tolerate a NaCl concentration of up to 8% was selected for this study. Based on the BIOLOG carbon source utilization, isolate CM94 was metabolically versatile and able to produce multiple plant growth-promoting attributes, such as indole acetic acid, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophore, hydrogen cyanide (HCN), and ammonia as well as solubilized phosphate. A polyphasic approach involving the analysis of fatty acid methyl ester (FAME) and 16S rRNA gene sequencing confirmed the identity of the isolate as Enterobacter sp. The results of greenhouse experiments revealed that isolate CM94 inoculation significantly enhanced the shoot length, root length, and fresh and dry weight of chickpea plants, under variable salinity stress. In addition, inoculation improved the chlorophyll, proline, sugar, and protein content in the tissues of the plant, while lowering lipid peroxidation. Furthermore, isolate CM94 reduced oxidative stress by enhancing the enzymatic activities of superoxide dismutase, catalase, and peroxidase compared to in the respective uninoculated plants.

CONCLUSIONS

Overall, the results suggested that using Enterobacter sp. CM94 could significantly mitigate salinity stress and enhance chickpea growth under saline conditions. Such studies will be helpful in identifying efficient microorganisms to alleviate salinity stress, which in turn will help, to devise ecofriendly microbial technologies.

Biocontrol strategies: an eco-smart tool for integrated pest and diseases management

For the burgeoning global population, sustainable agriculture practices are crucial for accomplishing the zero-hunger goal. The agriculture sector is very concerned about the rise in insecticide resistance and the Modern Environmental Health Hazards (MEHHs) that are problems for public health due to on pesticide exposure and residues. Currently, farming practices are being developed based on microbial bio-stimulants, which have fewer negative effects and are more efficient than synthetic agro-chemicals. In this context, one of the most important approaches in sustainable agriculture is the use of biocontrol microbes that can suppress phytopathogens and insects. Simultaneously, it is critical to comprehend the role of these microbes in promoting growth and disease control, and their application as biofertilizers and biopesticides, the success of which in the field is currently inconsistent. Therefore, editorial is part of a special issue titled "Biocontrol Strategies: An Eco-smart Tool for Integrated Pest and Disease Management" which focuses on biocontrol approaches that can suppress the biotic stresses, alter plant defense mechanisms, and offer new eco-smart ways for controlling plant pathogens and insect pests under sustainable agriculture.

Impact of carbendazim on cellular growth, defence system and plant growth promoting traits of Priestia megaterium ANCB-12 isolated from sugarcane rhizosphere

Agrochemicals are consistently used in agricultural practices to protect plants from pathogens and ensure high crop production. However, their overconsumption and irregular use cause adverse impacts on soil flora and non-target beneficial microorganisms, ultimately causing a hazard to the ecosystem. Taking this into account, the present study was conducted to determine the high dosage of fungicide (carbendazim: CBZM) effects on the rhizobacteria survival, plant growth promoting trait and reactive oxygen species (ROS) scavenging antioxidant enzyme system. Thus, a multifarious plant growth promoting rhizobacteria (PGPR) isolate, ANCB-12, was obtained from the sugarcane rhizosphere through an enrichment technique. The taxonomic position of the isolated rhizobacteria was confirmed through 16S rRNA gene sequencing analysis as Priestia megaterium ANCB-12 (accession no. ON878101). Results showed that increasing concentrations of fungicide showed adverse effects on rhizobacterial cell growth and survival. In addition, cell visualization under a confocal laser scanning microscope (CLSM) revealed more oxidative stress damage in the form of ROS generation and cell membrane permeability. Furthermore, the increasing dose of CBZM gradually decreased the plant growth promoting activities of the rhizobacteria ANCB-12. For example, CBZM at a maximum 3,000 μg/ml concentration decreases the indole acetic acid (IAA) production by 91.6%, ACC deaminase by 92.3%, and siderophore production by 94.1%, respectively. Similarly, higher dose of fungicide enhanced the ROS toxicity by significantly (p < 0.05) modulating the stress-related antioxidant enzymatic biomarkers in P. megaterium ANCB-12. At a maximum 3,000 μg/ml CBZM concentration, the activity of superoxide dismutase (SOD) declined by 82.3%, catalase (CAT) by 61.4%, glutathione peroxidase (GPX) by 76.1%, and glutathione reductase (GR) by 84.8%, respectively. The results of this study showed that higher doses of the fungicide carbendazim are toxic to the cells of plant-beneficial rhizobacteria. This suggests that a recommended dose of fungicide should be made to lessen its harmful effects.

Current advances and research prospects for agricultural and industrial uses of microbial strains available in world collections

Microorganisms are an important component of the ecosystem and have an enormous impact on human lives. Moreover, microorganisms are considered to have desirable effects on other co-existing species in a variety of habitats, such as agriculture and industries. In this way, they also have enormous environmental applications. Hence, collections of microorganisms with specific traits are a crucial step in developing new technologies to harness the microbial potential. Microbial culture collections (MCCs) are a repository for the preservation of a large variety of microbial species distributed throughout the world. In this context, culture collections (CCs) and microbial biological resource centres (mBRCs) are vital for the safeguarding and circulation of biological resources, as well as for the progress of the life sciences. Ex situ conservation of microorganisms tagged with specific traits in the collections is the crucial step in developing new technologies to harness their potential. Type strains are mainly used in taxonomic study, whereas reference strains are used for agricultural, biotechnological, pharmaceutical research and commercial work. Despite the tremendous potential in microbiological research, little effort has been made in the true sense to harness the potential of conserved microorganisms. This review highlights (1) the importance of available global microbial collections for man and (2) the use of these resources in different research and applications in agriculture, biotechnology, and industry. In addition, an extensive literature survey was carried out on preserved microorganisms from different collection centres using the Web of Science (WoS) and SCOPUS. This review also emphasizes knowledge gaps and future perspectives. Finally, this study provides a critical analysis of the current and future roles of microorganisms available in culture collections for different sustainable agricultural and industrial applications. This work highlights target-specific potential microbial strains that have multiple important metabolic and genetic traits for future research and use.

Current understanding of plant-microbe interaction through the lenses of multi-omics approaches and their benefits in sustainable agriculture

The success of sustainable agricultural practices has now become heavily dependent on the interactions between crop plants and their associated microbiome. Continuous advancement in high throughput sequencing platforms, omics-based approaches, and gene editing technologies has remarkably accelerated this area of research. It has enabled us to characterize the interactions of plants with associated microbial communities more comprehensively and accurately. Furthermore, the genomic and post-genomic era has significantly refined our perspective toward the complex mechanisms involved in those interactions, opening new avenues for efficiently deploying the knowledge in developing sustainable agricultural practices. This review focuses on our fundamental understanding of plant-microbe interactions and the contribution of existing multi-omics approaches, including those under active development and their tremendous success in unraveling different aspects of the complex network between plant hosts and microbes. In addition, we have also discussed the importance of sustainable and eco-friendly agriculture and the associated outstanding challenges ahead.

Salt tolerant PGPR strain Priestia endophytica SK1 promotes Fenugreek growth under salt stress by inducing nitrogen assimilation and secondary metabolites

AIMS

Soil salinity is a huge obstacle in crop production worldwide. Saline soil can reduce active chemical contents in medicinal plants of Leguminosae family through crippled normal nodule function. Intensive efforts are underway to improve yield and medicinal value of leguminous herbs under salt stress condition by using benign microbes. Here, an attempt was made to explore the salt tolerant bacteria associated with rhizosphere of fenugreek plant (Trigonella foenum-graecum L.) and to evaluate their impact on host plant growth and metabolite of pharmaceutical importance.

METHODS AND RESULTS

A salt tolerant plant growth promoting rhizobacterial (PGPR) strain Priestia endophytica SK1 isolated from fenugreek rhizospheric soil, which increased biomass and metabolite content in plants grown under saline stress. SK1 bacterial application induced nodule formation and enhanced nitrogen and phosphorus content under salt (100 mM NaCl) stress as compared to control plants. H2O2 production and lipid peroxidation as a measure of stress were observed high in control plants, while a reduction in these parameters was observed in plants inoculated with SK1. In addition, a significant effect was found on the phenolic compounds and trigonelline content in fenugreek plant inoculated with SK1 bacterium. An increased trigonelline content of about 54% over uninoculated control was recorded under salt stress.

CONCLUSION

The results of this study revealed that application of salt tolerant PGPR strain P. endophytica SK1 induced nitrogen fixation machinery that leads to alleviate salt stress and improved the biosynthesis of trigonelline content in fenugreek.

SIGNIFICANCE OF THE STUDY

This study extends our understanding on significance of rhizosphere microbiome and their beneficial role in plant health under environmental stress to promote agro-eco-farming practices.

Extending the benefits of PGPR to bioremediation of nitrile pollution in crop lands for enhancing crop productivity

Incessant release of nitrile group of compounds such as cyanides into agricultural land through industrial effluents and excessive use of nitrile pesticides has resulted in increased nitrile pollution. Release of nitrile compounds (NCs) as plant root exudates is also contributing to the problem. The released NCs interact with soil elements and persists for a long time. Persistent higher concentration of NCs in soil cause toxicity to beneficial microflora and affect crop productivity. The NCs can cause more problems to human health if they reach groundwater and enter the food chain. Nitrile degradation by soil bacteria can be a solution to the problem if thoroughly exploited. However, the impact of such bacteria in plant and soil environments is still not properly explored. Plant growth-promoting rhizobacteria (PGPR) with nitrilase activity has recently gained attention as potential solution to address the problem. This paper reviews the core issue of nitrile pollution in soil and the prospects of application of nitrile degrading bacteria for soil remediation, soil health improvement and plant growth promotion in nitrile-polluted soils. The possible mechanisms of PGPR that can be exploited to degrade NCs, converting them into plant useful compounds and synthesis of the phytohormone IAA from degraded NCs are also discussed at length.

Epigenetic regulation of salinity stress responses in cereals

Cereals are important crops and are exposed to various types of environmental stresses that affect the overall growth and yield. Among the various abiotic stresses, salt stress is a major environmental factor that influences the genetic, physiological, and biochemical responses of cereal crops. Epigenetic regulation which includes DNA methylation, histone modification, and chromatin remodelling plays an important role in salt stress tolerance. Recent studies in rice genomics have highlighted that the epigenetic changes are heritable and therefore can be considered as molecular signatures. An epigenetic mechanism under salinity induces phenotypic responses involving modulations in gene expression. Association between histone modification and altered DNA methylation patterns and differential gene expression has been evidenced for salt sensitivity in rice and other cereal crops. In addition, epigenetics also creates stress memory that helps the plant to better combat future stress exposure. In the present review, we have discussed epigenetic influences in stress tolerance, adaptation, and evolution processes. Understanding the epigenetic regulation of salinity could help for designing salt-tolerant varieties leading to improved crop productivity.

Insights into the Bacterial and Nitric Oxide-Induced Salt Tolerance in Sugarcane and Their Growth-Promoting Abilities

Soil salinity causes severe environmental stress that affects agriculture production and food security throughout the world. Salt-tolerant plant-growth-promoting rhizobacteria (PGPR) and nitric oxide (NO), a distinctive signaling molecule, can synergistically assist in the alleviation of abiotic stresses and plant growth promotion, but the mechanism by which this happens is still not well known. In the present study, in a potential salt-tolerant rhizobacteria strain, ASN-1, growth up to 15% NaCl concentration was achieved with sugarcane rhizosphere soil. Based on 16S-rRNA gene sequencing analysis, the strain ASN-1 was identified as a Bacillus xiamenensis. Strain ASN-1 exhibits multiple plant-growth-promoting attributes, such as the production of indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, siderophores, HCN, ammonia, and exopolysaccharides as well as solubilized phosphate solubilization. Biofilm formation showed that NO enhanced the biofilm and root colonization capacity of the PGPR strain ASN-1 with host plants, evidenced by scanning electron microscopy. The greenhouse study showed that, among the different treatments, the combined application of PGPR and sodium nitroprusside (SNP) as an NO donor significantly (p ≤ 0.05) enhanced sugarcane plant growth by maintaining the relative water content, electrolyte leakage, gas exchange parameters, osmolytes, and Na⁺/K⁺ ratio. Furthermore, PGPR and SNP fertilization reduced the salinity-induced oxidative stress in plants by modulating the antioxidant enzyme activities and stress-related gene expression. Thus, it is believed that the acquisition of advanced information about the synergistic effect of salt-tolerant PGPR and NO fertilization will reduce the use of harmful chemicals and aid in eco-friendly sustainable agricultural production under salt stress conditions.

Belowground fungal volatiles perception in okra (Abelmoschus esculentus) facilitates plant growth under biotic stress

Microbial volatile organic compounds (mVOCs) have great potential in plant ecophysiology, yet the role of belowground VOCs in plant stress management remains largely obscure. Analysis of biocontrol producing VOCs into the soil allow detailed insight into their interaction with soil borne pathogens for plant disease management. A root interaction trial was set up to evaluate the effects of VOCs released from Trichoderma viride BHU-V2 on soil-inhabiting fungal pathogen and okra plant growth. VOCs released into soil by T. viride BHU-V2 inhibited the growth of collar rot pathogen, Sclerotium rolfsii. Okra plants responded to VOCs by increasing the root growth (lateral roots) and total biomass content. VOCs exposure increased defense mechanism in okra plants by inducing different enzyme activities i.e. chitinase (0.89 fold), β-1,3-glucanase (0.42 fold), peroxidase (0.29 fold), polyphenol oxidase (0.33 fold) and phenylalanine lyase (0.7 fold) when inoculated with S. rolfsii. In addition, T. viride BHU-V2 secreted VOCs reduced lipid peroxidation and cell death in okra plants under pathogen inoculated condition. GC/MS analysis of VOCs blend revealed that T. viride BHU-V2 produced more number of antifungal compounds in soil medium as compared to standard medium. Based on the above observations it is concluded that okra plant roots perceive VOCs secreted by T. viride BHU-V2 into soil that involved in induction of plant defense system against S. rolfsii. In an ecological context, the findings reveal that belowground microbial VOCs may play an important role in stress signaling mechanism to interact with plants.

Seed biopriming with antagonistic microbes and ascorbic acid induce resistance in tomato against Fusarium wilt

Seed biopriming is an emerging technique to enhance seed germination under stress conditions. An integrated approach of tomato seed biopriming with ascorbic acid, Trichoderma asperellum BHU P-1 and Ochrobactrum sp. BHU PB-1 was applied to observe the response against wilt pathogen of tomato Fusarium oxysporum f. sp. lycopersici (FOL). Tomato seeds bioprimed with the aforementioned application expressed augmented seed germination and activated of defense response. Seed germination was recorded higher (80 %) at low concentration (1 pM) of ascorbic acid as compared to high concentration of 1 mM (41 %). Combination of both ascorbic acid and antagonistic microbe treatments (T5 & T6) significantly reduced disease incidence (up to 28 %) in tomato plants at 10 days. T5 and T6 treated plants exhibited higher accumulation of total phenol content and increased activity of Phenylammonia lyase (PAL), Peroxidase (PO), Chitinase (Chi) and Polyphenol oxidase (PPO) as compared to control (T1) plants. ROS formation in the form of H₂O₂ was also found to be reduced in combined treatment. Histochemical analysis revealed that phenylpropanoid pathway (lignin deposition) was more activated in combined priming treatment plants as compared to individual treatment upon challenge inoculation with FOL. Transcript expression analysis of defense genes confirmed the up-regulation of PAL (2.1 fold), Chi (0.92 fold), Pathogenesis related proteins (PR) (1.58 fold) and Lipoxygenase (Lox) (0.72 fold) in T6 treatment as compared to T1 treatment plants at 96 h. This study reveals that ascorbic acid treatment with antagonistic microbes through seed priming effectively induced seed germination and elicited defense mechanism to control wilt disease in tomato plants.

Sphingobacterium sp. BHU-AV3 Induces Salt Tolerance in Tomato by Enhancing Antioxidant Activities and Energy Metabolism

Salt tolerant bacteria can be helpful in improving a plant's tolerance to salinity. Although plant-bacteria interactions in response to salt stress have been characterized, the precise molecular mechanisms by which bacterial inoculation alleviates salt stress in plants are still poorly explored. In the present study, we aimed to determine the role of a salt-tolerant plant growth-promoting rhizobacteria (PGPR) Sphingobacterium BHU-AV3 for improving salt tolerance in tomato through investigating the physiological responses of tomato roots and leaves under salinity stress. Tomato plants inoculated with BHU-AV3 and challenged with 200 mM NaCl exhibited less senescence, positively correlated with the maintenance of ion balance, lowered reactive oxygen species (ROS), and increased proline content compared to the non-inoculated plants. BHU-AV3-inoculated plant leaves were less affected by oxidative stress, as evident from a reduction in superoxide contents, cell death, and lipid peroxidation. The reduction in ROS level was associated with the increased antioxidant enzyme activities along with multiple-isoform expression [peroxidase (POD), polyphenol oxidase (PPO), and superoxide dismutase (SOD)] in plant roots. Additionally, BHU-AV3 inoculation induced the expression of proteins involved in (i) energy production [ATP synthase], (ii) carbohydrate metabolism (enolase), (iii) thiamine biosynthesis protein, (iv) translation protein (elongation factor 1 alpha), and the antioxidant defense system (catalase) in tomato roots. These findings have provided insight into the molecular mechanisms of bacteria-mediated alleviation of salt stress in plants. From the study, we can conclude that BHU-AV3 inoculation effectively induces antioxidant systems and energy metabolism in tomato roots, which leads to whole plant protection during salt stress through induced systemic tolerance.

Exploration of multitrait antagonistic microbes against Fusarium oxysporum f.sp. lycopersici

Fusarium wilt is one of the major diseases of tomato causing extensive loss of production. Exploration of agriculturally important microbes (AIMs) for management of the tomato wilt is an ecofriendly and cost effective approach. In the present study, a total 30 Trichoderma and 30 bacterial isolates were screened in the laboratory for their biocontrol activity against Fusarium oxysporum f.sp. lycopersici (FOL). Out of all the isolates tested, Trichoderma asperellum BHU P-1 and Ochrobactrum sp. BHU PB-1 were found to show maximum inhibition of FOL in dual culture assay. Both the microbes also exhibited plant growth promoting activities such as phosphate solubilisation, production of siderophore, hydrogen cyanide (HCN), indole acetic acid (IAA) and protease activity. These microbes could be evaluated further in greenhouse and field studies for their potential use in management of Fusarium wilt of tomato.

PGPR-mediated expression of salt tolerance gene in soybean through volatiles under sodium nitroprusside

Increasing evidence shows that nitric oxide (NO), a typical signaling molecule plays important role in development of plant and in bacteria-plant interaction. In the present study, we tested the effect of sodium nitroprusside (SNP)-a nitric oxide donor, on bacterial metabolism and its role in establishment of PGPR-plant interaction under salinity condition. In the present study, we adopted methods namely, biofilm formation assay, GC-MS analysis of bacterial volatiles, chemotaxis assay of root exudates (REs), measurement of electrolyte leakage and lipid peroxidation, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for gene expression. GC-MS analysis revealed that three new volatile organic compounds (VOCs) were expressed after treatment with SNP. Two VOCs namely, 4-nitroguaiacol and quinoline were found to promote soybean seed germination under 100 mM NaCl stress. Chemotaxis assay revealed that SNP treatment, altered root exudates profiling (SS-RE), found more attracted to Pseudomonas simiae bacterial cells as compared to non-treated root exudates (S-RE) under salt stress. Expression of Peroxidase (POX), catalase (CAT), vegetative storage protein (VSP), and nitrite reductase (NR) genes were up-regulated in T6 treatment seedlings, whereas, high affinity K+ transporter (HKT1), lipoxygenase (LOX), polyphenol oxidase (PPO), and pyrroline-5-carboxylate synthase (P5CS) genes were down-regulated under salt stress. The findings suggest that NO improves the efficiency and establishment of PGPR strain in the plant environment during salt condition. This strategy may be applied on soybean plants to increase their growth during salinity stress.

Induced drought tolerance through wild and mutant bacterial strain Pseudomonas simiae in mung bean (Vigna radiata L.)

The present study focused on the overproducing mutant of a plant growth promoting rhizobacterium (PGPR) Pseudomonas simiae strain AU (MTCC-12057) for significant drought tolerance in mung bean plants. Five mutants namely AU-M1, AU-M2, AU-M3, AU-M4 and AU-M5 were made after treatment of wild type strain with N-methyl-N-nitro-N-nitrosoguanidine. Mutant strain AU-M4 was recorded for enhanced ACC deaminase (ACC-D) activity, indole acetic acid (IAA) production and inorganic phosphate (Pi) solubilization compared to wild strain and other four mutant strains under drought condition. AU-M4 showed higher phosphate solubilization index (8.17) together with higher ACC-D activity (98 nmol/mg/h) and IAA concentration (69.35 µg/ml) compared with the wild type P. simiae strain AU ACC-D activity (79 nmol/mg/h) and IAA concentration (38.98 µg/ml) respectively. In this report, we investigated the effect of both wild and mutant type bacterial strain on mung bean plants under drought stress. Results showed that mutant AU-M4 and wild type strain AU inoculated plants exhibited superior tolerance against drought stress, as shown by their enhanced plant biomass (fresh weight), higher water content, higher proline accumulation and lower osmotic stress injury. Mutant AU-M4 and wild strain AU inoculated plants reduced the ethylene level by 59 and 45% respectively, compared to the control under stress condition. Furthermore, bacterial inoculated plants showed enhanced induced systemic drought tolerance by reducing stomata size and net photosynthesis resulting higher water content in mung bean plants that may help in survival of plants during drought condition. To mitigate the effects of drought stress, use of PGPR will be needed to ensure sufficient production of food from crop plants. Taking current leads available, concerted future research is needed in this area, particularly on field evaluation with application of potential microorganisms.

Putative bacterial volatile-mediated growth in soybean (Glycine max L. Merrill) and expression of induced proteins under salt stress

AIMS

Plant root-associated rhizobacteria elicit plant immunity referred to as induced systemic tolerance (IST) against multiple abiotic stresses. Among multibacterial determinants involved in IST, the induction of IST and promotion of growth by putative bacterial volatile compounds (VOCs) is reported in the present study.

METHODS AND RESULTS

To characterize plant proteins induced by putative bacterial VOCs, proteomic analysis was performed by MALDI-MS/MS after exposure of soybean seedlings to a new strain of plant growth promoting rhizobacteria (PGPR) Pseudomonas simiae strain AU. Furthermore, expression analysis by Western blotting confirmed that the vegetative storage protein (VSP), gamma-glutamyl hydrolase (GGH) and RuBisCo large chain proteins were significantly up-regulated by the exposure to AU strain and played a major role in IST. VSP has preponderant roles in N accumulation and mobilization, acid phosphatase activity and Na(+) homeostasis to sustain plant growth under stress condition. More interestingly, plant exposure to the bacterial strain significantly reduced Na(+) and enhanced K(+) and P content in root of soybean seedlings under salt stress. In addition, high accumulation of proline and chlorophyll content also provided evidence of protection against osmotic stress during the elicitation of IST by bacterial exposure.

CONCLUSIONS

The present study reported for the first time that Ps. simiae produces a putative volatile blend that can enhance soybean seedling growth and elicit IST against 100 mmol l(-1) NaCl stress condition.

SIGNIFICANCE AND IMPACT OF THE STUDY

The identification of such differentially expressed proteins provide new targets for future studies that will allow assessment of their physiological roles and significance in the response of glycophytes to stresses. Further work should uncover more about the chemical side of VOC compounds and a detailed study about their molecular mechanism responsible for plant growth.

Rhizobacterium-mediated growth promotion and expression of stress enzymes in Glycine max L. Merrill against Fusarium wilt upon challenge inoculation

Wilt disease of soybean caused by a very common soil-borne fungus, Fusarium oxysporum is one of the most destructive diseases of the crop. The aim of the present study was to characterize plant growth-promotion activities and induced resistance of a rhizobacterial strain for the soybean plant against F. oxysporum. Rhizobacterium strain SJ-5 exhibited plant growth-promotion characteristics and antagonistic activity against the test pathogen on dual plate assay. It was identified as a Carnobacterium sp. A 950 bp PCR product was amplified from Carnobacterium sp. strain SJ-5, using zwittermicin A self-resistance gene-specific primers (zmaR). The strain produced indole 3-acetic acid (19 μg/ml) in the presence of salt stress and exhibited growth in Dworkin and Foster salt medium amended with 1-aminocyclopropane-1-carboxylate (ACC) through ACC deaminase activity (277 nmol/mg/h) as compared to the control. Strain seeds treated with the strain significantly enhanced the quorum of healthy plants after challenge inoculation at 14 days after seeding. An increase in the activity of stress enzymes after challenge inoculation with the test pathogen is reported. Treatment with the bacterium resulted in an increase in the chlorophyll content in the leaves in comparison with challenge-inoculated plants.

Effect of nitric oxide signaling in bacterial-treated soybean plant under salt stress

To understand protective roles of nitric oxide against salt stress, the effects of exogenous sodium nitroprusside on activities of lipoxygenase, peroxidase, phenylalanine ammonialyase, catalase, superoxide dismutase enzymes, proline accumulation, and distribution of sodium in soybean plants under salt were determined. Application of sodium nitroprusside + bacterium enhanced plant growth-promotion characteristics, activities of different enzymes, and proline accumulation in the presence of sodium nitroprusside under salt stress. Treatment with NaCl at 200 mM and sodium nitroprusside (0.1 mM) reduced Na⁺ levels but increased K⁺ levels in leaves in comparison with the NaCl-treated plants. Correspondingly, the plants treated with exogenous sodium nitroprusside and NaCl maintained a lower ratio of [Na⁺]/[K⁺] in NaCl-stressed plants.

Soybean growth-promotion by Pseudomonas sp. strain VS1 under salt stress

In the present study, we employ Pseudomonas sp. strain VS1 showed in vitro plant growth-promotion characteristics and promoted soybean seed emergence under salt stress. Strain produced indole 3-acetic acid in the presence of salt stresses that exhibited high numbers of lateral root as compared to control. Bacterial strain exhibited growth in DF salt medium amended with 1-aminocyclopropane-1-carboxylate through ACC deaminase activity. Bacterial-treated soybean seeds were subjected to salt stress and significantly enhanced emergence at 7 days after seeding. Strain untreated soybean plants had a 33% seed germination when 200 mM NaCl was applied at 0 DAS and the root length was significantly decreased compared to the strain treated plants (LSD0.05 = 0.21). Most importantly, the application of 200 mM NaCl at 0 DAS resulted in only a 9% of lateral root in untreated plants as compared to strain treated plants.

Neural tube defects and congenital hydrocephalus in the Sultanate of Oman

A retrospective study was carried out in Oman to determine the incidence of neural tube defects (NTD) and congenital hydrocephalus (CH) and to identify any possible associations. National data retrieved from hospital records revealed the incidence of NTD in Oman to be comparatively low (1.25 per 1000), but the incidence of CH was much higher than that seen in Western Europe (0.44 per 1000) and was found to be associated with high rates of other congenital anomalies and neonatal death. There were no specific environmental factors associated with NTD and high environmental temperatures during the tropical desert summer (temperatures reach 48 degrees C) were excluded as a causative factor. In spina bifida families, later born children were more likely to be affected and there was also an association with increased maternal but not paternal age. Much higher consanguinity rates were noted in families with NTD and CH than in the general population.

Necrotizing fasciitis: a serious complication of omphalitis in neonates

Necrotizing fasciitis occurs when the inflammation (cellulitis) spreads beyond the umbilicus to include the subcutaneous tissue and underlying fascia. Presently, omphalitis is relatively uncommon because of aseptic delivery techniques and antimicrobial therapy. One hundred three neonates aged 7 to 28 days, with varying degrees of omphalitis, were treated on an outpatient or inpatient basis between 1989 and mid-1993. The neonates were full-term and weighed at least 2.5 kg. Patients with necrotizing fasciitis initially appear deceptively well, which results in less-than-optimum treatment at the outset, followed by a rapid and fulminating downhill course, in turn resulting in death within 24 to 72 hours. Early recognition of the condition, with aggressive resuscitation, appropriate antibiotics, and early surgery are necessary to salvage this high-risk group. The risk factors that may predict the development of necrotizing fasciitis and its early detection are discussed.

Progressive hydrocephalus in teenage spina bifida patients

Many spina bifida patients with shunts for hydrocephalus do not require shunt revisions for several years. These children are often considered to be no longer shunt dependent, only to develop rising intracranial pressure (ICP) requiring surgery in the second decade. We present three patients who, despite never having had a C.S.F. shunt, developed rising intracranial pressure in early teenage years. The diagnosis was delayed because of the lack of appreciation of this clinical entity. One child died, the second suffered permanent neurological damage, and the third recovered completely. We suggest that both shunted and non-shunted patients have a common cause for the late rise in ICP.

New cervical approach for tracheopexy

Deficiency of the tracheal cartilage is known to occur with oesophageal atresia resulting in abnormal compressibility. It does not require treatment unless symptomatic. Symptoms comprise apnoeic or cyanotic spells, often precipitated by feeds, and recurrent chest infections. When other causes such as stricture, recurrent fistula and gastro-oesophageal reflux have been excluded, the abnormality can be diagnosed radiologically and endoscopically. Previously tracheopexy through a lateral thoracic approach has been described. We describe three patients who had a successful tracheopexy through an anterior cervical approach, which is simpler, and a fourth in whom there was partial alleviation.

Comparison of two methods of prophylaxis against CSF shunt infection

In a series of 68 operations for insertion or revision of cerebrospinal fluid shunts the incidence of infection was reduced from 20% in controls to 4.2% when systemic and intrathecal or intra-shunt gentamicin prophylaxis was employed. The only infection occurring in the latter group was due to an organism resistant to gentamicin. No reduction in infection rate was noted when povidone iodine was instilled into the wounds.