Metabolomics, biomass and lignocellulosic total sugars analysis in foxtail millet (setaria italica) inoculated with different combinations of plant growth promoting bacteria and mycorrhiza

Foxtail millet (Setaria italica) is the second most widely produced millet with potential as a biofuel source. Employment of plant growth promoting bacteria (PGPB) and mycorrhiza could serve as environment-friendly alternatives for the use of excessive NPK fertilizers and producing biofuel. The highest increase of biomass was associated with endomycorrhiza combined with PGPB in comparison to control. Nuclear magnetic resonance (NMR) analysis detected 28 metabolites in foxtail shoot with most of them upregulated in ecto/endomycorrhiza group and combined with PGPB. The upregulation of metabolites associated with synthesis of amino acids correlated positively with biomass. The inoculation with both PGPB and endomycorrhiza gave the best results with reference to total sugar yield. Our study indicates that PGPB and endomycorrhiza combination is well suited for enhancing biomass and boosting sugar yield, which are useful attributes for utilizing foxtail millet as a biofuel source

The Role of Plant Growth-Promoting Microorganisms (PGPMs) and Their Feasibility in Hydroponics and Vertical Farming

There are many reasons for the increase in hydroponics/soil-free systems in agriculture, and these systems have now advanced to the form of vertical farming. The sustainable use of space, the reduction in water use compared to soil-based agriculture, the lack of pesticides, the ability to control nutrient inputs, and the implementation of user-friendly technology for environmental control and harvesting are all factors that have made the global market for vertical farming predicted to reach more than USD 10.02 billion by 2027. By comparison, soil-based agriculture consumes 20 times more water, and some agricultural practices promote soil deterioration and cause environmental pollution. Plant growth-promoting microorganisms (PGPMs) have been used extensively in traditional agriculture to enhance plant growth, environmental stress tolerance, and the efficacy of phytoremediation in soil-based farming. Due to the controlled atmosphere in hydroponics and vertical farms, there is strong potential to maximize the use of PGPMs. Here, we review the leveraging of plant growth-promoting microorganism mechanisms in hydroponics and vertical farming. We recommend a synchronized PGPM treatment using a biostimulant extract added to the hydroponic medium while also pre-treating seeds or seedlings with a microbial suspension for aquaponic and aeroponic systems

How Can We Stabilize Soil Using Microbial Communities and Mitigate Desertification?

The desert, which covers around one-third of Earth’s continental surface, is defined as the harshest terrestrial environment and comprises a highly extensive biome of the terrestrial ecosystem. Microorganisms are key drivers that maintain the integrity of desert terrestrial ecosystems. Over the past few decades, desertification has increased owing to changes in rainfall patterns and global warming, characterized by land degradation, loss of microbial diversity (biocrust diversity), and multifunctionality with time. Soil stabilization is a geotechnical modality that improves the physiochemical properties of the soil. Biological modality is an emerging method that attracts the scientific community for soil stabilization. Enriching the soil with microorganisms such as some bacteria geniuses (Cystobacter, Archangium, Polyangium, Myxococcus, Stigmatella and Sorangium, Bacillus, Acinetobacter, Proteus, Micrococcus, and Pseudom) or Cyanobacteria (Oscillatoria pseudogeminata, Chroococcus minutus, Phormidium Tenue, and Nostoc species), and Lichens (Collema sps., Stellarangia sps., and Buellia species) might contribute to stabilizing the soil and mitigating desertification. In this timeline review article, we summarize the biological method of soil stabilization, especially focusing on the role of microorganisms in soil stabilization in the desert

SORGHUM AND MAIZE AS BIOLOGICAL MODELS FOR STUDYING THE EFFECT OF MICROBIAL INTERACTIONS ON GROWTH AND METAL TOLERANCE IN MINING-IMPACTED SOIL

In the current study, two C4 plants, sorghum (BTx623) and maize (rugosa) grown in mining-impacted soil were subjected to plant growth promoting bacteria (PGPB) Pseudomonas sp. TLC 6-6.5-4 and arbuscular mycorrhiza individually and combined. Seedlings were maintained in the greenhouse under the same conditions for the same period of time for all three treatments. Three treatments were used, Pseudomonas sp. TLC 6-6.5-4 (B group), arbuscular mycorrhizal mix (My group), and combination of PGPB and mycorrhiza (My+B group). Dead inoculum was used as the control group. To gain insights on how plants react at the molecular level, data was collected at the end of maize life cycle after 62 days and sorghum after 90 days. Plant physiological responses under different treatments were investigated. These included maize and sorghum biomass, element uptake and changes in metabolites. Biochemical and molecular mechanisms involved in sorghum and maize tolerance were identified. Further, proteomic analysis was integrated with physiological responses. Our results revealed that different microbial treatments lead to different physiological responses in maize and sorghum. The biomass and element uptake increased in all of the three treatments (B, My and My+B) for both sorghum and maize with minor variations. In addition, three metabolic pathways were common between maize and sorghum based on upregulated metabolites. We hypothesize that plants ensure carbon flux and energy supply for carbohydrate integration into biomass through fatty acid synthesis and glyoxylate metabolism whereas, alanine, aspartate and glutamate metabolism are used to facilitate nitrogen incorporation. The increase of element uptake associated with metabolite changes in maize or sorghum root might be due to metabolic reprogramming to overcome macronutrient deficiency. Sorghum protein analysis showed common upregulation of 45 proteins. Among these proteins, fructokinase correlated positively with biomass, primary element uptake and metabolites associated with biomass and element uptake. The PGPB showed the highest number of upregulated proteins, where one-fourth of them involved oxidoreductase and DNA repair activity. These findings confirm that PGPB increased sorghum tolerance through ROS scavenging system to balance cellular function during stress. In the current study, two C4 plants, sorghum (BTx623) and maize (rugosa) grown in mining-impacted soil were subjected to plant growth promoting bacteria (PGPB) Pseudomonas sp. TLC 6-6.5-4 and arbuscular mycorrhiza individually and combined. Seedlings were maintained in the greenhouse under the same conditions for the same period of time for all three treatments. Three treatments were used, Pseudomonas sp. TLC 6-6.5-4 (B group), arbuscular mycorrhizal mix (My group), and combination of PGPB and mycorrhiza (My+B group). Dead inoculum was used as the control group. To gain insights on how plants react at the molecular level, data was collected at the end of maize life cycle after 62 days and sorghum after 90 days. Plant physiological responses under different treatments were investigated. These included maize and sorghum biomass, element uptake and changes in metabolites. Biochemical and molecular mechanisms involved in sorghum and maize tolerance were identified. Further, proteomic analysis was integrated with physiological responses. Our results revealed that different microbial treatments lead to different physiological responses in maize and sorghum. The biomass and element uptake increased in all of the three treatments (B, My and My+B) for both sorghum and maize with minor variations. In addition, three metabolic pathways were common between maize and sorghum based on upregulated metabolites. We hypothesize that plants ensure carbon flux and energy supply for carbohydrate integration into biomass through fatty acid synthesis and glyoxylate metabolism whereas, alanine, aspartate and glutamate metabolism are used to facilitate nitrogen incorporation. The increase of element uptake associated with metabolite changes in maize or sorghum root might be due to metabolic reprogramming to overcome macronutrient deficiency. Sorghum protein analysis showed common upregulation of 45 proteins. Among these proteins, fructokinase correlated positively with biomass, primary element uptake and metabolites associated with biomass and element uptake. The PGPB showed the highest number of upregulated proteins, where one-fourth of them involved oxidoreductase and DNA repair activity. These findings confirm that PGPB increased sorghum tolerance through ROS scavenging system to balance cellular function during stress

Plant Growth Promoting Rhizobacteria (PGPR) Regulated Phyto and Microbial Beneficial Protein Interactions

Plant Growth Promoting Rhizobacteria (PGPR) influence plants’ physiological characteristics, metabolites, pathways and proteins via alteration of corresponding gene expression. In the current study, a total of 42 upregulated uncharacterized sorghum bicolor root proteins influenced by PGPR were subjected to different analyses: phylogenetic tree, protein functional network, sequences similarity network (SSN), Genome Neighborhood Network (GNN) and motif analysis. The screen for homologous bacterial proteins to uncover associated protein families and similar proteins in non-PGPRs was identified. The sorghum roots’ uncharacterized protein sequences analysis indicated the existence of two protein categories, the first being related to phytobeneficial protein family associated with DNA regulation such as Sulfatase, FGGY_C, Phosphodiesterase or stress tolerance such as HSP70. The second is associated with bacterial transcriptional regulators such as FtsZ, MreB_Mbl and DNA-binding transcriptional regulators, as well as the AcrR family, which existed in PGPR and non PGPR. Therefore, Plant Growth-Promoting Rhizobacteria (PGPR) regulated phytobeneficial traits through reciprocal protein stimulation via microbe plant interactions, both during and post colonization

Genetic screening for quality-of-life improvement and post–genetic testing consideration in Saudi Arabia

The Saudi genome project started in 2013 with a great hope to improve medical care and disease prevention. Among the genes are those related to nutrition and fitness that can optimize an individual’s lifestyle. Our aim was to review the knowledge and acceptance of nutrition and fitness genetic testing to enhance the quality of life among the population of Saudi Arabia. For the study an electronic questionnaire consisting of 27 questions was prepared, and it was answered by 302 respondents. The respondents’ demographics showed about 50% of respondents were aged 18–25 years and about 50% of respondents were aged 26–60 years. More than 50% of respondents were interested in having a genetic test to enhance their health, while 40% were interested in having a genetic test to enhance their fitness. Less than 50% of respondents had an understanding of the effects of coffee, macronutrition and micronutrition, elements, and enzyme activity. These results represented a contribution to the discussion on the relevance of genetic testing validity and acceptance among the population of Saudi Arabia. The results might help in producing specific guidelines on genetic testing and genomic analysis and help in the implementation of fitness and future health plans in cooperation with Saudi genome projects. Future study will focus on population structure and genetic frequency related to specific diets or fitness

Mycorrhiza and heavy metal resistant bacteria enhance growth, nutrient uptake and alter metabolic profile of sorghum grown in marginal soil

The main challenge for plants growing in nutrient poor, contaminated soil is biomass reduction, nutrient deficiency and presence of heavy metals. Our aim is to overcome these challenges using different microbial combinations in mining-impacted soil and focus on their physiological and biochemical impacts on a model plant system, which has multiple applications. In the current study, sorghum BTx623 seedlings grown in mining-impacted soil in greenhouse were subjected to plant growth promoting bacteria (PGPB or B) alone, PGPB with arbuscular mycorrhizal fungi (My), My alone and control group with no treatment. Root biomass and uptake of most of the elements showed significant increase in all treatment groups in comparison with control. Mycorrhiza group showed the best effect followed by My + B and B groups for uptake of majority of the elements by roots. On the contrary, biomass of both shoot and root was more influenced by B treatment than My + B and My treatments. Metabolomics identified compounds whose levels changed in roots of treatment groups significantly in comparison to control. Upregulation of stearic acid, sorbitol, sebacic acid and ferulic acid correlated positively with biomass and uptake of almost all elements. Two biochemical pathways, fatty acid biosynthesis and galactose metabolism, were regulated in all treatment groups. Three common pathways were upregulated only in My and My + B groups. Our results suggest that PGPB enhanced metabolic activities which resulted in increase in element uptake and sorghum root biomass whether accompanied with mycorrhiza or used solely

Mycorrhiza and PGPB modulate maize biomass, nutrient uptake and metabolic pathways in maize grown in mining-impacted soil

Abiotic stress factors including poor nutrient content and heavy metal contamination in soil, can limit plant growth and productivity. The main goal of our study was to evaluate element uptake, biomass and metabolic responses in maize roots growing in mining-impacted soil with the combination of arbuscular mycorrhiza (My) and plant growth promoting bacteria (PGPB/B). Maize plants subjected to PGPB, My and combined treatments showed a significant increase in biomass and uptake of some elements in shoot and root. Metabolite analysis identified 110 compounds that were affected ≥2-fold compared to control, with 69 metabolites upregulated in the My group, 53 metabolites in the My+B group and 47 metabolites in B group. Pathway analysis showed that impact on glyoxylate and dicarboxylate metabolism was common between My and My+B groups, whereas PGPB group showed a unique effect on fatty acid biosynthesis with significant increase in palmitic acid and stearic acid. Differential regulation of some metabolites by mycorrhizal treatment correlated with root biomass while PGPB regulated metabolites correlated with biomass increase in shoot. Overall, the combination of rhizospheric microorganisms used in our study significantly increased maize nutrient uptake and growth relative to control. The changes in metabolic pathways identified during the symbiotic interaction will improve our understanding of mechanisms involved in rhizospheric interactions that are responsible for increased growth and nutrient uptake in crop plants

Proteomics provides insights into biological pathways altered by plant growth promoting bacteria and arbuscular mycorrhiza in sorghum grown in marginal soil

Sorghum is an economically important crop, a model system for gene discovery and a biofuel source. Sorghum seedlings were subjected to three microbial treatments, plant growth promoting bacteria (B), arbuscular mycorrhizal (AM) fungi mix with two Glomus species (G. aggregatum and G. etunicatum), Funelliformis mosseae and Rhizophagus irregularis (My), and B and My combined (My + B). Proteomic analysis was conducted followed by integration with metabolite, plant biomass and nutrient data. Out of 366 differentially expressed proteins in sorghum roots, 44 upregulated proteins overlapping among three treatment groups showed positive correlation with sorghum biomass or element uptake or both. Proteins upregulated only in B group include asparagine synthetase which showed negative correlation with biomass and uptake of elements. Phosphoribosyl amino imidazole succinocarboxamide protein with more than 50-fold change in My and My + B groups correlated positively with Ca, Cu, S and sucrose levels in roots. The B group showed the highest number of upregulated proteins among the three groups with negative correlation with sorghum biomass and element uptake. KEGG pathway analysis identified carbon fixation as the unique pathway associated with common upregulated proteins while biosynthesis of amino acids and fatty acid degradation were associated with common downregulated proteins. Protein-protein interaction analysis using STRING identified a major network with thirteen downregulated proteins. These findings suggest that plant-growth-promoting-bacteria alone or in combination with mycorrhiza enhanced radical scavenging system and increased levels of specific proteins thereby shifting the metabolism towards synthesis of carbohydrates resulting in sorghum biomass increase and uptake of nutrients