Non-inoculated Control Research Articles

Root endophytic fungus Serendipita indica modulates barley leaf blade proteome by increasing the abundance of photosynthetic proteins in response to salinity.

The present study aimed at analysing the proteome pattern of the leaf blade of barley (Hordeum vulgare L.) in Serendipita indica-colonised plants to decipher the molecular mechanism of S. indica-mediated salt stress. This work is aligned with our previous research on barley leaf sheath to study proteomic pattern variability in leaf blade and sheath of barley plant in response to salinity and S. indica inoculation. The experiment was conducted using a completely randomised factorial design with four replications and two treatments: salinity (0 and 300mmoll-1 NaCl) and fungus (noninoculated and S. indica-inoculated). The leaf blades of the salt-treated S. indica-colonised and noninoculated plants were harvested after 2weeks of salt treatment for the physiological and proteomic analyses. After exposure to 300mmoll-1 NaCl, shoot dry matter production in noninoculated control plants decreased 84% which was about twofold higher than inoculated plants with S. indica. However, the accumulation of sodium in the shoot of S. indica-inoculated plants was significantly lower than the control plants. Analysis of the proteome profile revealed a high number of significantly up-regulated proteins involved in photosynthesis (26 out of 42 identified proteins). The results demonstrated how the enhanced plant growth and salt stress resistance induced by S. indica was positively associated with the up-regulation of several proteins involved in photosynthesis and carbohydrate metabolism. In fact, S. indica improved photosynthesis in order to reach the best possible performance of the host plant under salt stress. Current research provides new insight into the mechanism applied by S. indica in reducing the negative impacts of salt stress in barley at physiological and molecular levels.

Physiological response of Arizona cypress to Cd-contaminated soil inoculated with arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria

Increasing some industrial activities has been constantly contaminated the soil with different toxic metals leading to serious environmental concerns. However, some beneficial soil microorganisms would be useful tools for reducing toxic effects of heavy metals without producing toxic residuals. Therefore, present study was conducted to evaluate potential role of Pseudomonas fluorescens and arbuscular mycorrhizal fungi (AMF) in reducing cadmium toxicity in the Arizona cypress seedlings both individually and in combination. Factorial experiment was conducted based on a completely randomized design with three factors comprising AMF inoculation (Rhizophagus irregularis or Funneliformis mosseae or a mixture of both species, and non-inoculated controls), bacterial inoculation (P. fluorescens or Non-inoculated), and five levels of Cd (0, 5, 10, 15, and 20 mg kg−1) using three replications. Results of this study showed that, Arizona cypress growth decreased when exposed to high levels of Cd contamination. However, co-inoculation plants with all mycorrhizae and P. fluorescens grown under the highest levels of Cd contamination, showed increased photosynthetic pigments. Furthermore, AMF and P. fluorescens increased ascorbate peroxidase activity, which is responsible for the elimination of H2O2 when plants exposed to Cd stress. Moreover, high levels of Cd contamination negatively influenced phosphorus uptake by the plants, especially in control plants. Moreover, in seedlings inoculated with mycorrhizal fungi, accumulation of Cd was found to be less, apparently as a result of AMF modification of the influx of Cd into the host plants, as confirmed by reduced hydrogen peroxide and enhanced antioxidant enzyme activities compared to the control plants. AMF treatments increased glomalin related soil proteins concentration compared to the control plants. Also, the highest amount of glomalin production was observed in two species of Mix and FM. In conclusion, either co-inoculation with AMF and P. fluorescens or individual inoculation with AMF could potentially ameliorate harmful effects of Cd on Arizona cypress growth. .

Evaluation of the GENE-UP®Salmonella Method for the Detection of Salmonella Species in a Broad Range of Foods and Select Environmental Surfaces: Collaborative Study, First Action 2020.02.

The GENE-UP®Salmonella assay (Performance Tested MethodSM [PTM] 121802) is a PCR detection method that utilizes fluorescence resonance energy transfer (FRET) hybridization probes for the rapid detection of Salmonella species in foods and on environmental surfaces. The purpose of this validation was to evaluate the method's interlaboratory performance for submission to AOAC INTERNATIONAL for adoption as First Action Official Method of AnalysisSM. The GENE-UP method was evaluated in a multi-laboratory study using unpaired test portions for one food matrix, raw ground beef (80% lean). The candidate method was compared to the US Department of Agriculture (USDA), Food Safety Inspection Service, Microbiology Laboratory Guidebook (MLG) 4.10 reference method. An alternative confirmation procedure, using ASAP™ and CHROMID®Salmonella chromogenic agars, was included in the validation study. Fifteen collaborators from 14 laboratories participated. Three levels of contamination were evaluated: a non-inoculated control level (0 CFU/test portion), a low contamination level (∼0.7 CFU/test portion), and a high contamination level (∼2 CFU/test portion). Data were analyzed using the probability of detection (POD) statistical model. The dLPODC values with 95% confidence interval for the GENE-UP Salmonella method, with either alternative or traditional confirmation, were: 0.00 (-0.03, 0.03), -0.02 (-0.15, 0.12), and 0.02 (-0.03, 0.09) for the non-inoculated, low, and high contamination levels respectively. The dLPODC results demonstrate no difference in performance between the candidate method and reference method for the matrix evaluated. The GENE-UP Salmonella method, with ASAP and CHROMID Salmonella, provides industry with a simplified, rapid, and accurate workflow for the detection of Salmonella in a broad range of foods and select environmental surfaces.

Effect of inoculating Lactobacillus sakei strains alone or together with Staphylococcus xylosus on microbiological, physicochemical, fatty acid profile, and sensory quality of Tunisian dry‐fermented sausage

The use of starter cultures in the industrial manufacture of meat products has become common practice. We have investigated the use of Lactobacillus sakei F, isolated from a commercial starter culture, and Lactobacillus sakei 23K, from a French sausage, alone or together with Staphyloccus xylosus, as starter cultures, during the industrial manufacture of Tunisian dry-fermented sausages. Samples from the same raw matter were collected after up to 45 days of maturation and were subjected to microbiological, physicochemical, nutritional, and sensory analyses. Furthermore, we demonstrated that the use of L. sakei F or L. sakei 23K as starter strains produced a fermented sausage with similar or even better quality than sausages fermented with L. sakei 23K + S. xylosus or the commercial starter. Our study found that L. sakei 23K could have a great potential for use as a starter culture during the commercial production of dry-fermented sausage. Novelty impact statement Lactobacillus sakei F and 23K strains can be used alone or in association with Staphylococcus xylosus as starter cultures for the manufacture of Tunisian dry-fermented sausages. Sausages produced with L. sakei F and 23K strains display better nutritional and sensory profiles, compared with the non-inoculated controls, as well as sausages inoculated with the commercial starter culture.

Yield Losses Caused by Barley Yellow Dwarf Virus-PAV Infection in Wheat and Barley: A Three-Year Field Study in South-Eastern Australia.

Barley yellow dwarf virus (BYDV) is transmitted by aphids and significantly reduces the yield and quality of cereals worldwide. Four experiments investigating the effects of barley yellow dwarf virus-PAV (BYDV-PAV) infection on either wheat or barley were conducted over three years (2015, 2017, and 2018) under typical field conditions in South-Eastern Australia. Plants inoculated with BYDV-PAV using viruliferous aphids (Rhopalosiphum padi) were harvested at maturity then grain yield and yield components were measured. Compared to the non-inoculated control, virus infection severely reduced grain yield by up to 84% (1358 kg/ha) in wheat and 64% (1456 kg/ha) in barley. The yield component most affected by virus infection was grain number, which accounted for a large proportion of the yield loss. There were no significant differences between early (seedling stage) and later (early-tillering stage) infection for any of the parameters measured (plant height, biomass, yield, grain number, 1000-grain weight or grain size) for either wheat or barley. Additionally, this study provides an estimated yield loss value, or impact factor, of 0.91% (72 kg/ha) for each one percent increase in natural BYDV-PAV background infection. Yield losses varied considerably between experiments, demonstrating the important role of cultivar and environmental factors in BYDV epidemiology and highlighting the importance of conducting these experiments under varying conditions for specific cultivar–vector–virus combinations.

Effect of bacterial endophytes inoculation on morphological and physiological traits of sorghum (Sorghum bicolor (L.) Moench) under drought

Globally, drought stress causes the negative impact on agriculture production. However, microbial inoculation is the suitable cost-effective technology to attenuate the drought stress. The aim of this experiment was conducted to evaluate the impact of microbial inoculation on morpho-physiological characters of sorghum under moisture stress condition. A pot experiment with sorghum was conducted to access the role of previously identified bacterial endophyte strains. For comparison, two non-inoculated control treatments (T1: absolute control and T2: drought control) were maintained to compare the drought and inoculation effect. Drought was imposed at flowering stage and soil moisture was measure at frequent days. When the soil moisture attains close to zero, plants were rehydrated. During drought and rehydration period, plant morphological and physiological characters were evaluated. Drought stress drastically reduces the plant characters in control (T2-uninoculated) plant. Whereas, in the presence of bacterial inoculation considerably reduces the drought effect also Bacillus sp. inoculation treatment promoted better recovery during their rehydration process than absolute control. Overall, Bacillus sp. inoculation was the most promising bacterium for possible field trials.

Effect of nodumax inoculant on morpho-physiological parameters, nutrient content and yield of soybean (Glycine max. L)

The field study was carried out at the Teaching and Research Farm of Faculty of Agriculture and Veterinary Medicine of Imo State University, Owerri, to investigate the effect of Nodumax inoculants on Morpho-Pysiological parameters, Nutrient content and yield of Soybean (Glycine max). The experimental design was Randomized Complete Block Design with five treatments and four replications. Treatments consist of Gum Arabic Slurry, Honey Slurry, Powdered milk Slurry, Sugar Slurry ( as adhesive agents) and control. The results obtained indicated that Nodumax inoculation, with adhesive agents especially Gum Arabic improved the Morpho- Physiological parameters such as plant heights, leaf area, leaf area index, leaf area ratio, Relative Growth Rate (RGR) and Net Assimilation Rate (NAR) and shoot dry weight compare to the control. Inoculation increased soybean grain yield across the various adhesive agents ranging from 909.45kg/ha for non-inoculated control to 1002.99kg/ha for inoculated using Gum Arabic, as sticker agent. Proximate composition of inoculated seeds was significantly (P<0.05) improved compare to the control. However, it was observed that Nodumax inoculation correspond to increase in soybean growth characteristics which subsequently increased the yield and improved the nutritional status of soybean. This study has shown that the type of adhesive for coating of seed during rhizobium inoculation could impact positive change in growth parameters, Nutritional status and yield of soybean.

Maize-associated bacteria from the Brazilian semiarid region boost plant growth and grain yield

Microbial inoculants containing plant-growth-promoting bacteria (PGPB) are low-cost tools to improve crop yield. The prospection of new strains should enable the selection of efficient microbial agents for commercial inoculants. This study aimed to isolate and select PGPB for maize in the Brazilian semiarid region. A field trial using two maize genotypes was implemented, and bacteria were isolated from maize stems and roots. The bacteria were grown in semi-solid BMGM or solid Dyg’s media, and they were characterized in vitro with respect to five plant growth-promoting mechanisms. Twenty-seven strains were assessed for growth promotion using potted maize plants. Nine bacterial strains improved plant biomass and/or N accumulation in shoots and were selected for field assessment and identification by 16S rRNA sequencing. Fourteen and 65 bacterial strains were isolated, respectively, in the semi-solid and solid medium. Auxin production without L-Tryptophan and antagonism against F. verticillioides were found for bacteria isolated on solid medium, and other characteristics were found for the strains from semi-solid medium. These strains were classified as Bacillus (5), Brevibacillus (2), Staphylococcus (1), and Paenibacillus (1). Five strains (Bacillus spp. ESA 593, ESA 597, ESA 599, ESA 600, and Paenibacillus sp. ESA 601) improved maize yield (56–87%) compared with the non-inoculated and non-fertilizated (N) control. In conclusion, the Brazilian drylands maize plants harbor several potential PGPB, and five elite strains were retrieved in the present study. These strains will be used for future network field assays to assure their agronomic performance.

Evaluation of biogenic markers-based phenotyping for resistance to Aphanomyces root rot in field pea

Biogenic volatile organic compounds (VOCs) emitted by plants can reveal information about plant adaptation, defense processes, and biological pathways. Thus, such VOC data may be utilized to capture phenotypic plant responses to the environment. In this study, the main objective was to evaluate the potential of biogenic compounds, including VOCs, to phenotype two pea cultivars, Ariel (susceptible) and Hampton (high levels of partial resistance) for resistance to Aphanomyces root rot disease. Plants were monitored non-destructively for VOC emission at three-time points (15, 20, and 30 days after inoculation, DAI) using dynamic headspace sampling with gas chromatography-flame ionization detection (GC-FID) system, as well as destructively at the end of the experiments, using solvent extraction and pyrolysis of both shoot and root tissues. A non-inoculated control (mock-inoculated with distilled water) was utilized to compare the plant responses within a cultivar. The common chemical peaks between control and inoculated samples of both cultivars (RTcm) were analyzed after normalizing the relative peak intensity of inoculated samples with those of control samples, prior to a comparison between cultivars. In addition, unique chemical peaks (RTuq) present in inoculated samples, but not in control samples were also identified and their relative peak intensities were compared. Among the released green leaf volatiles (RTcm), the normalized relative peak intensity of hexanal emission, at 20 DAI, was higher in Ariel than that of Hampton. In addition, several putative chemical peaks (both RTcm and RTuq), previously known as indicators for disease response, exhibited some differences in their emission rates between pea cultivars in at least one of the time points. The destructive sampling revealed that shoot samples produced more putative unique biomarkers (RTuq) than the root samples. Based on the differences in putative chemical peaks between cultivars, this initial study supports the concept of utilization of biogenic biomarker-based phenotyping in distinguishing levels of resistance in the evaluated pea cultivars. More research is needed to further this approach for phenotyping other plant cultivars. Upon validation, the VOC profile integrated with high-throughput VOC sensing techniques can serve as a novel mechanism for phenotyping disease responses in crops.

Evaluating nematode resistance of grapevine rootstocks based on Xiphinema index reproduction rates in a fast screening assay

By feeding on grapevine roots, the ectoparasite Xiphinema index transmits grapevine fanleaf virus (GFLV), causing fanleaf degeneration in the plant. Therefore, rootstock breeding programs are considered a key to resistance to both threats. Previous screening depends on long-lasting inoculation experiments and mainly focuses on evaluating gall formation on the parasitized roots to identify potential resistance in grapevines. Since the roots of grapevine rootstocks resistant to X. index and even those of susceptible cultivars showed no reliable gall formation after parasitism, and further, root thickening was regularly found on non-inoculated control plants, nematode reproduction rates were used to validate rootstock phenotypes regarding susceptibility or resistance to X. index. For our approach, a glass vial assay was performed, and 35 days after inoculation the nematode population was determined by counting juveniles after the extraction. Reproduction rates were high on susceptible rootstock cultivars and decreased the more resistant a cultivar is considered. Besides focusing solely on root gall formation, the nematode reproduction rate should be included as a reliable indicator for resistance screening. The described assay setup enables the evaluation of resistance levels by fast screening to select promising rootstock candidates.

THE EFFECTIVENESS OF PHYTOLECTINS AND LECTIN COMPOSITIONS APPLICATION FOR SPRAYING PLANTS DURING VEGETATION

The effectiveness of the soybean plants spraying with the soybean seed lectin solution during vegetation (against the background of seed inoculation with nodule bacteria and without seed inoculation), as well as the effectiveness of the winter wheat plants spraying with lectin-bacterial composition in green-house and field experiments was investigated respectively. It was found that spraying of soybeans in the phase of two trifoliate leaves development with a specific lectin against the background of pre-sowing seed inoculation with rhizobia caused a significantly positive effect on the functional activity of the symbiotic apparatus. The nitrogen-fixing activity of the rhizosphere microbiota remained unchanged, which may indicate the vector of lectin action when sprayed through the plant. At the same time, the activation of plants vegetative growth was noted, which was maximally manifested by the height of their above ground part. The activity of exogenous sprayed lectin was less pronounced on the background of seed inoculation with rhizobia compared to non-inoculated plants. Plants spraying with soybean lectin against the background of seed inoculation provided an increase in harvest compared to non-inoculated control by 12.8 g/plant, but by the factor of lectin action this increase was only 1.15 g/plant and was insignificant. Non-inoculated soybean plants when sprayed with lectin formed a harvest that was significantly higher (by 3.86 g/plant) than that of plants in the absence of lectin. At this, the increase by the factor of lectin action was 22%. The spraying of winter wheat plants in the phase of mass spring germinations with the Azolec preparation (without pre-sowing seed inoculation) contributed to a significant increase in harvest by 1.6 c/ha. Therefore, the application of soybean and wheat plants spraying, respectively, with soybean seed lectin and lectin-bacterial Azolec preparation (wheat lectin),without involving pre-sowing seed inoculation, provided a greater degree of plants productive potential realization compared to control (without pre-sowing seed inoculation and plants spraying during vegetation).

Nodule-associated bacteria alter the mutualism between arbuscular mycorrhizal fungi and N2 fixing bacteria

Legumes can interact simultaneously with multiple microbial partners in symbiosis, including arbuscular mycorrhizal fungi (AMF), N2-fixing bacteria, and nodule-associated bacteria. However, our understanding of their functional diversity and interactions remains limited. The objective of this study was to evaluate individual and combined effects of these three symbioses on the abundance and function of the symbionts, including the growth, nitrogen content, nodulation and root traits of Mimosa scabrella (Bracatinga), a common leguminous tree in South America. We grew seedlings in a growth chamber for 90 days using sterile soil inoculated with all combinations of AMF, N2 fixing and nodule-associated bacteria. We found that the tripartite symbiosis formed by host, AMF and N2 fixing bacteria increased shoot biomass 3.7x and N content 5.2x relative to non-inoculated controls. This response was 71% greater than the sum of the respective individual treatments, confirming for the first time in M. scabrella a synergistic effect of such dual inoculation. In contrast, the presence of nodule-associated bacteria in a tetrapartite symbiosis resulted in a 57.7% reduction in the number of nodules in any treatment where N2 fixing bacteria were present. Concurrently, total AM root colonization decreased by approximately 50% in the tetrapartite compared to the tripartite symbiosis. We conclude that the tripartite symbiosis formed by M. scabrella, N2 fixing bacteria, and AMF can act synergistically in promoting plant biomass and N2 fixation. However, nodule-associated bacteria can act “opportunistically”, causing a detrimental effect on the tripartite mutualism. Our findings highlight the functional complexity of multipartite symbioses and how interactions among partners can determine biological processes and outcomes.

The effect of endophytic fungi on growth and nickel accumulation in Noccaea hyperaccumulators

The role of endophytic fungi isolated from different populations of European Ni hyperaccumulators was investigated in regard to the microorganisms' ability to enhance the hyperaccumulation of Ni in Noccaea caerulescens. Effects of particular species of endophytic fungi on adaptation of N. caerulescens to excess Ni were tested by co-cultivation with single strains of the fungi. Seven of these had a positive effect on plant biomass production, whereas two of the tested species inhibited plant growth; biomass production of inoculated plants was significantly different compared to non-inoculated control. Inoculation with six fungal strains: Embellisia thlaspis, Pyrenochaeta cava, Phomopsis columnaris, Plectosphaerella cucumerina, Cladosporium cladosporioides and Alternaria sp. stimulated the plant to uptake and accumulate more Ni in both roots and shoots, compared to non-inoculated control. P. columnaris was isolated from all plant species sampled. Strains isolated from Noccaea caerulescens and Noccaea goesingensis increased Ni root and shoot accumulation of their native hosts (compared to non-inoculated control). Inoculation of different populations of Noccaea with P. columnaris of foreign origin did not cause its host to accumulate more Ni, with the exception of the Ni-unadapted ecotype of N. goesingensis. Inoculation with P. columnaris from N. caerulescens significantly improved Ni uptake, but the effect of the fungus was not as prominent as in the case of N. caerulescens. By comparing the transcriptomes of N. caerulescens and N. goesingensis from Flatz inoculated with P. columnaris, we showed that enhanced uptake and accumulation of Ni in the plants is accompanied by an upregulation of several genes mainly involved in plant stress protection and metal uptake and compartmentation.

1-Aminocyclopropane-1-carboxylate (ACC) Deaminase Gene in Pseudomonas azotoformans Is Associated with the Amelioration of Salinity Stress in Tomato.

Although bacteria with 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity have been used to mitigate biotic and abiotic stresses in crops, it is not well known whether the ACC deaminase gene (acdS) in Pseudomonas azotoformans is related to the alleviation of salt stress by the bacterium. This study aimed to evaluate the effects of acdS in P. azotoformans strain CHB 1107 on the nutrient uptake and growth of tomato plants under salt stress. The acdS mutant (CHB 1107 M) of P. azotoformans CHB 1107 was obtained through bacterial conjugation. Wild-type (CHB 1107 WT) and CHB 1107 M were used to inoculate tomato plants grown in a soil or solution with an electrical conductivity of 6 dS/m adjusted by NaCl. CHB 1107 M completely lost the ability to produce ACC deaminase, whereas the complementation of acdS in CHB 1107 M preserved its ACC deaminase activity. CHB 1107 WT significantly reduced the production of ethylene and proline by tomato plants under salt stress, increasing the shoot and root dry weights of tomato plants compared with the noninoculated control and CHB 1107 M. In addition, tomato plants inoculated with CHB 1107 M showed a significant reduction in K (27.5%), Ca (23.0%), and Mn uptake (17.5%) compared with those inoculated with CHB 1107 WT. In contrast, CHB 1107 WT significantly reduced Na uptake by tomato plants in comparison to CHB 1107 M in saline soil conditions. In addition, the inoculation of tomato plants with CHB 1107 WT resulted in a higher K/Na ratio than in those inoculated with CHB 1107 M and the noninoculated control. These findings suggest that acdS in P. azotoformans is associated with the amelioration of salinity stress in tomato. Plant transformation with acdS and the field application of P. azotoformans may be used as potential management tools for crops under salt stress.

Fermentation of African nightshade leaves with lactic acid bacterial starter cultures

The interest in the consumption of African indigenous leafy vegetables increased in African countries, e.g. Kenya, within the last years. One example of African indigenous leafy vegetables is African nightshade (Solanum scabrum) which is nutritious, rich in proteins and micronutrients and therefore could contribute to a healthy diet. African nightshade has several agricultural advantages. However, the most important disadvantage is the fast perishability which leads to enormous post-harvest losses. In this study, we investigated the fermentation of African nightshade as a post-harvest processing method to reduce post-harvest losses. The two lactic acid bacterial starter strains Lactiplantibacillus plantarum BFE 5092 and Limosilactobacillus fermentum BFE 6620 were used to inoculate fermentations of African nightshade leaves with initial counts of 106–107 cfu/ml. Uninoculated controls were conducted for each fermentation trial. Fermentations were performed both in Kenya and in Germany. The success of the inoculated starter cultures was proven by the measurement of pH values and determination of lactic acid concentration. Lactobacilli strains dominated the microbiota of the starter inoculated samples in contrast to the non-inoculated controls. This was supported by classical culture-dependent plating on different microbiological media as well as by the culture-independent molecular biological methods denaturing gradient gel electrophoresis and 16S rRNA gene high-throughput amplicon sequencing. We could demonstrate that the use of the selected starter cultures for fermentation of African nightshade leaves led to controlled and reliable fermentations with quick acidification. Thus, controlled fermentation with appropriate starter cultures is a promising method for post-harvest treatment of African nightshade leaves.

Silicon nanoparticle-mediated seed priming and Pseudomonas spp. inoculation augment growth, physiology and antioxidant metabolic status in Melissa officinalis L. plants

Pre-sowing seed priming and seedling inoculation with bioelicitor improve growth and phytochemical constituents of medicinal plants. This study was aimed to investigate the role of seed priming with silicon nanoparticles (nSi, 0, 100 and 500 mg/L) and inoculation of seedling originated from primed seeds with rhizobacteria strains (Pseudomonas fluorescens and P. putida) on physiological and metabolic attributes of Melissa officinalis L. Foliar application of P. putida on plants raised from nSi-primed (at 500 mg/L) seeds showed the wider deposition of nSi on root surface compared with that of P. fluorescens, however, P. fluorescens application on plants grown from nSi-primed (at 100 mg/L) seeds showed more open stomata on leaf surface than non-inoculated controls. Individual treatments of seed priming and seedling inoculation significantly (P < 0.05) increased plant biomass indices, leaf relative water content, photosynthetic pigments values, total soluble protein and phenolic contents, essential oil yield and their all (except thymol) major constituents, neral, geranial, and geranyl acetate compared with the control. However, the maximum increase in measured traits was recorded in mixed treatment of seed priming and inoculation of plants raised from primed seeds with rhizobacteria. Furthermore, the employed treatment combinations enhanced the free radical scavenging activities of plant extracts compared with the individual treatment and untreated control samples. According to the multivariate analyses, the treatments applied in combinations (especially seed priming at 100 mg nSi/L and seedling inoculation with P. putida) scores were substantially farther from the other treatments mean. Overall, seed priming with nSi along with seedling inoculation with pseudomonas strains play vital role in the increase in both primary and secondary metabolites of lemon balm plants.

Mutualism between Dark Septate Endophytes (DSEs) and their host plants under metal stress: a case study

In the current study, a model of ‘fungus-root’ interaction was designed using host Zea mays inoculated with a metal-tolerant dark septate endophyte (DSE) strain of Exophiala pisciphila H93 both under nutritional- (Zn0) and zinc-stressed (Zn550) conditions. We found that the co-cultured maize benefited from the alleviated excessive Zn toxicity by its root-associated E. pisciphila, through significantly decreasing root Zn under Zn550 conditions, or promoting the nutritional Zn in maize shoots and roots by 34.03% and 22.13% under Zn0 conditions, respectively, compared with non-inoculated controls. Interestingly, H93 further enhanced the maize Zn tolerance by the bioaugmented Zn compartmentation in root cell walls to reduce the proportion of Zn in maize root soluble fractions and cell organelles under Zn550 stress. In exchange for the maize carbon cost, the H93 extraradical hyphae tended to accumulate more toxic Zn, compared with H93 mycelia in the in vitro culture under Zn550 conditions, and vice versa the co-cultured maize also promoted Zn tolerance of H93 via the repartitioning of subcellular Zn. Our results suggest the potentially mutual association of E. pisciphila and its host maize, by trading carbon for the increased abiotic tolerance.

Enhanced biological control of root-knot nematode, Meloidogyne incognita, by combined inoculation of cotton or soybean seeds with a plant growth-promoting rhizobacterium and pectin-rich orange peel.

LC-MS analysis of plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis AP203 supernatants indicated the presence of nematode-inhibiting compounds that increased in abundance when B. velezensis AP203 was grown on orange peel. Meloidogyne incognita J2 were incubated with B. velezensis AP203 spores and orange peel, spores alone, orange peel alone, or with a non-inoculated control, and the combination of B. velezensis AP203 with orange peel resulted in 94% mortality of M. incognita juveniles (p ≤ 0.05). The J2 mortality rate for B. velezensis alone was 53%, compared to 59% mortality with orange peel, and the non-inoculated control exhibited 7% mortality. When tested on soybeans raised in a greenhouse, it was observed that when grown in the presence of orange peel, B. velezensis AP203 culture broth, cell suspension or supernatant reduced the numbers of M. incognita eggs per g of root at 45 days after planting (DAP) compared to inoculated controls in soybean and cotton (p ≤ 0.05). Likewise, soybean root length and fresh root weight significantly increased after inoculation with B. velezensis AP203 amended with orange peel. In cotton, shoot and root length significantly increased after inoculation with cell pellets of B. velezensis AP203 amended with orange peel compared to the M. incognita inoculated control. These data indicate that B. velezensis AP203 responds to growth on pectin-rich orange peel by production of biologically active secondary metabolites that can promote plant growth and inhibit root-knot nematode viability.

Dual inoculation of soybean with &lt;i&gt;Rhizophagus irregularis&lt;/i&gt; and commercial &lt;i&gt;Bradyrhizobium japonicum&lt;/i&gt; increases nitrogen fixation and growth in organic and conventional soils

<abstract> Soil amendment with beneficial microorganisms is gaining popularity among farmers to alleviate the decline of soil fertility and to increase food production and maintain environmental quality. However, farm management greatly influence soil microbial abundance and function, which overly affects crop growth and development. In this work, greenhouse experiments involving soybeans were conducted to evaluate the effects of bradyrhizobia and arbuscular mycorrhizal fungi (AMF) dual inoculation on nodulation, AMF root colonization, growth and nutrient acquisition under contrasting farming systems. The experimental treatments were AMF and/or bradyrhizobia inoculation and dual inoculation on SC squire soybean variety. The exotic AMF inoculants used were <italic>Funneliformis mosseae</italic> (BEG 12) and <italic>Rhizophagus irregularis</italic> (BEG 44) while bacteria were commercial <italic>Bradyrhizobium japonicum</italic> (USDA110) and native bradyrhizobia isolates. Experiments with soil samples from organic and conventional farms were set out using a completely randomized design with three replicates. The results demonstrated that bradyrhizobia and AMF dual inoculation consistently and significantly enhanced soybean nodule dry weight (NDW), shoot dry weight (SDW) and AMF root colonization compared with individual bradyrhizobia<italic>, </italic> AMF and non-inoculated control. Moreover, organic soil significantly (p = 0.001) increased soybean SDW, NDW and AMF root colonization compared to conventional soil. Remarkably, shoot nutrients content differed in organic and conventional farming where, shoot nitrogen, phosphorus, potassium and organic carbon were higher in organic farming than the latter. Among individual inoculants, <italic>Rhizophagus irregularis</italic> out-performed <italic>Funneliformis mosseae, </italic> while commercial <italic>Bradyrhizobium japonicum</italic> showed higher performance than native bradyrhizobia. Our results demonstrated the importance of organic farming, AMF and bradyrhizobia dual inoculation in enhancing soybean growth and nutrient acquisition. However, field trials should be assessed to determine the good performance of bradyrhizobia and AMF dual inoculation in organic farming before being popularized and adopted by farmers as a sustainable agronomical management strategy to increase soil fertility and food productivity. </abstract>

Zajednički efekat Bacillus izolata i pepela na kvalitet zemljišta i biljke - preliminarni ogled u saksijama sa analizom potencijalno toksicnih elemenata

The use of biomass ash in agriculture can have advantages such as improved soil quality and environmentally friendly ash disposal. Moreover, in combination with microbial inoculants, biomass ash can have a beneficial effect on plant growth. The study investigated the effect of biomass ash and inoculums of three Bacillus isolates on the quality of soil and barley plants. The greenhouse pot experiment included five treatments and two control soils: control - without any amendment and control with mineral fertilizer (CAN). Treatments included soil (3 kg/pot) and biomass ash (30 g/pot) with and without calcium ammonium nitrate or with bacterial inoculum. Biomass ash was collected after combustion of soybean straw. Bacillus sp. were isolated from the rhizosphere soil of alfalfa. The presence of PGP traits (Indole-3-Acetic Acid and siderophores) was confirmed by the quantitative tests for the three Bacillus isolates used (B1, BS1, BMG1). The ash, soil and plant (collected in crop maturity stage) samples were tested for: total N, C, S, and plant available P2O5 and K2O as well as for the content of potentially toxic and hazardous microelements (As, Cd, So, Cr, Cu, Mn, Ni, Pb, Zn). Inoculation of seeds with Bacillus inoculums (in vitro) showed a significant effect on seedling growth compared to the non-inoculated control. Addition of ash significantly reduced soil acidity and increased content of plant available P and K compared to the controls, while combination of ash and microorganism, increased amount of available P compared to the treatment with ash only. Barley biomass yield was increased more than double when treated with ash and by 87.62% when treated with ash+BMG1 compared to control. The lowest yield was obtained in the treatment where only CAN was added. The content of potentially toxic microelements in the soil and barley shoots was below the maximum allowed concentrations. The use of biomass ash alone was effective in terms of soil nutritional and physical properties resulting in yield increase. However, the use of ash in combination with Bacillus isolates in addition to positive effect on soil and plant quality resulted in a higher barley biomass than the combination of ash with CAN. This study showed that biomass ash can be used as fertilizer on acidic soils with low nutrient content alone or in combination with bacterial inoculants. The synergistic effect of ash with microorganisms can provide an environmentally friendly approach in agriculture to reduce the need for chemical fertilizers and solve the problem of biomass ash disposal.