Heavy metal accumulation in agricultural land causes crop production losses worldwide. Metal homeostasis within cells is tightly regulated. However, homeostasis breakdown leads to accumulation of ...reactive oxygen species (ROS). Overall plant fitness under stressful environment is determined by coordination between roots and shoots. But little is known about organ specific responses to heavy metals, whether it depends on the metal category (redox or non-redox reactive) and if these responses are associated with heavy metal accumulation in each organ or there are driven by other signals. Maize seedlings were subjected to sub-lethal concentrations of four metals (Zn, Ni, Cd and Cu) individually, and were quantified for growth, ABA level, and redox alterations in roots, mature leaves (L1,2) and young leaves (L3,4) at 14 and 21 days after sowing (DAS). The treatments caused significant increase in endogenous metal levels in all organs but to different degrees, where roots showed the highest levels. Biomass was significantly reduced under heavy metal stress. Although old leaves accumulated less heavy metal content than root, the reduction in their biomass (FW) was more pronounced. Metal exposure triggered ABA accumulation and stomatal closure mainly in older leaves, which consequently reduced photosynthesis. Heavy metals induced oxidative stress in the maize organs, but to different degrees. Tocopherols, polyphenols and flavonoids increased specifically in the shoot under Zn, Ni and Cu, while under Cd treatment they played a minor role. Under Cu and Cd stress, superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were induced in the roots, however ascorbate peroxidase (APX) activity was only increased in the older leaves. Overall, it can be concluded that root and shoot organs specific responses to heavy metal toxicity are not only associated with heavy metal accumulation and they are specialized at the level of antioxidants to cope with.
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•Maize organs of different types and ages respond differently to heavy metals.•Cluster analyses results grouped Cd–Cu and Zn–Ni groups with regard to antioxidant responses in maize seedling.•Mature leaves are more sensitive to heavy metals compared to younger ones.•Different antioxidant enzymes are induced in different organs.
•eCO2 treatment supports the hypocholesterolaemic potential of fenugreek seeds.•eCO2-treated seeds are more potent in inhibiting cholesterol micellar solubility.•Inhibitory action of fenugreek seeds ...against pancreatic lipase is promoted by eCO2.•eCO2 induces the accumulation of phenolics, flavonoids, saponins and alkaloids.
A high level of serum cholesterol is a major cause of atherosclerosis. Fenugreek is a well-known hypocholesterolaemic agent with amazing phytochemical composition. Due to its impact on plant metabolism, CO2 enrichment was tested as a strategy to support functional values in fenugreek seeds. Phytochemical composition and biological activities of three fenugreek cultivars (G2, G6 and G30) grown under ambient (aCO2, 400 μmol mol−1) and elevated CO2 (eCO2, 620 μmol mol−1) were assessed. Applying eCO2 improved physical parameters of fenugreek seeds, and enhanced their biological activities. A significant increase in hypocholesterolaemic potential, as indicated by inhibition of cholesterol micellar solubility and pancreatic lipase activity, was recorded. In addition, antioxidant, anti-lipid peroxidation and antibacterial activities were improved. These enhanced biological activities were accompanied by improved seed chemical composition at the primary and secondary metabolic levels. Therefore, eCO2 treatment represents an efficient strategy to increase the hypocholesterolaemic, antioxidant and antibacterial activities of fenugreek seeds.
Soil pH is commonly considered a dominant factor affecting the function of microbiota. Few studies, however, have focused on communities of bacteria able to solubilize inorganic phosphate (iPSB), ...which are important for the mobilization of soil phosphorus (P), because finding an effective method to assess the abundance and diversity of iPSB communities is difficult. We used a newly reported method of database alignment and quantified the gene pqqC to analyze the compositions of iPSB communities from five soils with pH gradients ranging from 4 to 8. The iPSB community structure differed significantly between these soil types. Among iPSB community, Bacillus was the dominant genus, followed by Arthrobacter and Streptomyces. A redundancy analysis indicated that soil pH was the most important of 15 soil factors and their pairwise interactions, accounting for 5.12% of the variance. The abundance of the iPSB communities increased with pH within the gradients which was confirmed by experimental adjustment of pH, suggesting that the defect P status in high pH soil was speculated as the driving force of iPSB community population. Our study demonstrated the dominant role of soil pH on the iPSB community, which may contribute to the understanding the possible mechanism of microbial P mobilization for better improvement of P use-efficiency.
Aluminum (Al) toxicity is a major constraint for crop production in acid soils. Therefore, looking for sustainable solutions to increase plant tolerance to Al toxicity is needed. Although several ...studies addressed the potential utilization of silica or silicon dioxide nanoparticles (SNPs) to ameliorate heavy metal phytotoxicity, the exact mechanisms underlying SNPs-induced stress tolerance are still unknown. The current study investigated how SNPs could mitigate Al toxicity in maize plants grown on acidic soil. The impact of Al alone or in combination with SNPs on Al accumulation and detoxification, plant growth, photosynthetic C assimilation and redox homeostasis has been investigated. Al accumulation in stressed-maize organs reduced their growth, decreased photosynthesis related parameters and increased production of reactive oxygen species, through induced NADPH oxidase and photorespiration activities, and cell damage. These effects were more pronounced in roots than in leaves. SNPs ameliorated Al toxicity at growth, physiological and oxidative damage levels. Co-application of SNPs significantly reduced the activities of the photorespiratory enzymes and NADPH oxidase. It stimulated the antioxidant defense systems at enzymatic (superoxide dismutase, catalase, ascorbate and glutathione peroxidases) and non-enzymatic (ascorbate, glutathione, polyphenols, flavonoids, tocopherols, and FRAP) levels. Moreover, SNPs increased organic acids accumulation and metal detoxification (i.e. glutathione-S-transferase activity) in roots, as a protective mechanism against Al toxicity. The SNPs induced-protective mechanisms was dependent on the applied Al concentration and acted in organ-specific manner. Overall, the current study suggests the promising application of SNPs as an innovative approach to mitigate Al phytotoxicity in acidic soils and provides a comprehensive view of the cellular and biochemical mechanisms underlying this mitigation capacity.
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•Aluminum (Al) reduced the growth and photosynthesis and induced oxidative stress in maize plants.•Nano-SiO2 (SNPs) did not affect Al accumulation but mitigated its phytotoxicity.•SNPs induced organic acid exudation by roots and metal detoxification activity.•SNPs reduced ROS production and improved ROS scavenging systems.•Maize responses to Al and SNPs were in a dose- and organ-specific manner.
The direct application of inorganic-phosphate-solubilizing bacteria (iPSBs) for improving the efficiency of phosphorus (P) use leads to a low rate of bacterial survival. Biochar is a good inoculum ...carrier for microbial survival, and diverse feedstocks can have different effects. We generated an iPSB community using seven selected iPSB strains with various phylogenic taxonomies and P-solubilizing abilities. Biochar was then inoculated with the iPSB community and applied to soil in pots seeded with rape (Brassica napus). Growth of the rape for four weeks and the effects of biochars produced from six raw feedstocks, rice straw, rice husks, soybean straw, peanut shells, corn cobs and wood, were compared. The synthetic iPSB community had a larger capacity to solubilize inorganic P and exude organic anions than any of the individual strains. The structure of the iPSB community was analyzed by high-throughput sequencing four weeks after inoculation. All seven iPSB strains were detected, dominated by Arthrobacter defluvii 06-OD12. The abundance of the iPSB community was significantly correlated with rape biomass, P content and P uptake (P < 0.05). The biochar amendments conferred 6.86–24.24% survival of the iPSB community, with the straw biochars conferring the highest survival. The available-P content of the biochar rather than soil pH was the dominant factor for iPSB community structure, suggesting that the biochar material was critical for the survival and functioning of the iPSB community. Our study demonstrates the feasibility of biochar-assisted iPSB improvement of crop growth and P uptake.
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•Inorganic phosphate solubilizing bacteria (iPSB) community was structure-analyzed.•A synthetic iPSB community with biochar immobilization was applied.•The straw biochar was proved the best on the abundance of iPSB community.•The iPSB community abundance improved the rape growth and phosphate uptake.
Many studies have discussed the influence of elevated carbon dioxide (eCO2) on modeling and crop plants. However, much less effort has been dedicated to herbal plants. In this study, a robust ...monitoring for the levels of 94 primary and secondary metabolites and minerals in two medicinal herbs, basil (Ocimum basilicum L.) and peppermint (Mentha piperita L.), grwon under both ambient (aCO2, 360 ppm) and eCO2 (620 ppm) was performed. We also assessed how the changes in herbal tissue chemistry affected their biological activity. Elevated CO2 significantly increased herbal biomass, improved the rates of photosynthesis and dark respiration, and altered the tissue chemistry. Principal Component Analysis of the full data set revealed that eCO2 induced a global change in the metabolomes of the two plants. Moreover, Hierarchical Clustering Analyses showed quantitative differences in the metabolic profiles of the two plants and in their responsiveness to eCO2. Out of 94 metabolites, 38 and 31 significantly increased in basil and peppermint, respectively, as affected by eCO2. Regardless of the plant species, the levels of non-structural carbohydrates, fumarate, glutamine, glutathione, ascorbate, phylloquinone (vitamin K1), anthocyanins and a majority of flavonoids and minerals were significantly improved by eCO2. However, some metabolites tended to show species specificity. Interestingly, eCO2 caused enhancement in antioxidant, antiprotozoal, anti-bacterial and anticancer (against urinary bladder carcinoma; T24P) activities in both plants, which was consequent with improvement in the levels of antioxidant metabolites such as glutathione, ascorbate and flavonoids. Therefore, this study suggests that the metabolic changes triggered by eCO2 in the target herbal plants improved their biological activities.
A Gram-positive, aerobic, non-motile, non-spore forming strain, designated DSD51Wᵀ, was isolated using a resuscitative technique from a soil sample collected from Kyoto park, Japan, and characterized ...by using a polyphasic approach. The morphological and chemotaxonomic properties of the isolate were typical of those of members of the genus Rhodococcus. Strain DSD51Wᵀwas found to form a coherent cluster with Rhodococcus hoagii ATCC 7005ᵀ, Rhodococcus equi NBRC 101255ᵀ, Rhodococcus defluvii Callᵀand Rhodococcus kunmingensis YIM 45607ᵀas its closest phylogenetic neighbours in 16S rRNA gene sequence analysis. However, the DNA–DNA hybridization values with the above strains were 58.2 ± 2.2, 58.4 ± 1.9, 45.1 ± 1.4 and 40.3 ± 4.7 %, respectively. In combination with differences in physiological and biochemical properties, strain DSD51Wᵀcan be concluded to represent a novel species of the genus Rhodococcus, for which the name Rhodococcus soli sp. nov. is proposed, with the type strain DSD51Wᵀ(=KCTC 29259ᵀ = JCM 19627ᵀ = DSM 46662ᵀ = KACC 17838ᵀ).
This study aimed to show the effect of bile acid (BA) and xylanase (Xyl) supplementation on the growth, fat digestibility, serum lipid metabolites, and ileal digesta viscosity of broilers. A total of ...720 1 d old male broilers were allocated to one of nine treatments with four replicates in each under a factorial design arrangement of three levels of BA (0 %, 0.25 %, and 0.50 %) and three levels of Xyl (0 %, 0.05 %, and 0.10 %) supplementation. The duration of the experiment was 35 d (7-42 d). Growth performance, blood lipids, fat digestibility, and ileal digesta viscosity were determined. The experimental treatments did not affect feed intake (FI) and weight gain (WG). Supplementation of BA or Xyl did not significantly ameliorate the feed conversion rate (FCR) (
). The addition of BA linearly increased fat digestibility. At 7-21 d of age, the addition of BA or Xyl had a significant (
) increase in serum cholesterol (Chol) but no significant difference for other serum lipid parameters in broiler chickens fed with Xyl in the starter and grower periods. However, the supplementation of 0.5 % BA at 7-21 d of age significantly increased the Chol and low-density-lipoprotein (LDL) levels. The results of this trial revealed that the supplementation of xylanases had a great effect on the degradation of arabinoxylan from wheat, which led to a relatively greater reduction in ileal digesta viscosity; it was also found that supplementation of BA significantly increased the concentration of serum lipid metabolites, whereas BA and Xyl supplementation linearly increased the fat digestibility of the birds fed wheat and tallow diets.
The search for environment-friendly, economical and healthy alternatives to agrochemicals tempted us to evaluate the potential of naturally occurring actinomycetes to improve soil properties, plant ...growth and photosynthesis, grain yield and chemical composition of economically important cereals (wheat, barley, oat, maize and sorghum). To this end, actinomycetes were isolated from soils of local cereals fields, then their biological activities, namely antibacterial, antiprotozoal, antioxidant, and phenolic and flavonoid contents were evaluated. The four most active isolates (9, 16, 24 and 26) were selected and used for enriching the soils until seed set. Each isolate was separately applied. Seeds of the selected cereals were grown in the actinomycete-enriched soils. The soils were analyzed for their electrical conductivity, pH values, total phenolics, organic matter and mineral content. At the vegetative stage, chlorophyll content and gas exchange rates were measured. Mature seeds were then harvested, the yield was evaluated and the seeds were analyzed for their primary and secondary metabolites. The selected isolates improved the grain yield in all tested cereals and most noticeably in barley and maize as compared to control counterparts. These positive effects were probably a result of increased carbon gain due to higher chlorophyll and photosynthetic rate. Isolate 26 showed the highest effect on grains composition profiles followed by the isolate 16. Phenolics and sugars of all grains increased by treatment with the tested isolates. Isolate 26 was the most effective in this regard. All isolates generally improved vitamins, amino acids and organic acids contents in grains. However, fatty acids profile showed a decrease in the content of all measured fatty acids by isolate 26 and an increase in the contents by isolate 16. These results emphasize the potential of actinomycete enrichment as an alternative to agrochemicals and strongly suggest that they can be used in organic farming.
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•Several actinomycetes were isolated and identified.•According to their biological activities, 4 out 27 isolates were selected.•Active actinomycetes induced soil fertility e.g., nutrients availability.•Active actinomycetes-treated cereals showed improved yield and grain quality.•Improved grain yield and quality were correlated with increased photosynthesis.
A Gram-stain-positive, aerobic, non-motile, coryneform bacterium, designated strain EGI 60002ᵀ, was isolated from the halophyte Suaeda physophora. Cells were coryneform shaped and polymorphic. ...Phylogenetic analysis based on 16S rRNA gene sequences showed that the new isolate was closely related to Actinotalea ferrariae CF5-4ᵀ(95.8 % gene sequence similarity). The peptidoglycan type of strain EGI 60002ᵀwas A4β, containing L-Orn-D-Ser-D-Asp. The cell-wall sugars were mannose, ribose, rhamnose and glucose. The major fatty acids (>5 %) of strain EGI 60002ᵀwere iso-C₁₄:₀, iso-C₁₅:₀, anteiso-C₁₅:₁A and anteiso-C₁₅:₀. The predominant respiratory quinone was MK-10(H₄). The major polar lipids were diphosphatidylglycerol (DPG), one unidentified phosphoglycolipid (PGL) and one unidentified phospholipid (PL1). The genomic DNA G+C content was 72.3 mol%. On the basis of morphological, physiological, chemotaxonomic data, and phylogenetic analysis, strain EGI 60002ᵀshould be classified as a novel species within the genus Actinotalea, for which the name Actinotalea suaedae sp. nov. is proposed. The type strain is EGI 60002T (=JCM 19624ᵀ = KACC 17839ᵀ = KCTC 29256ᵀ).
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