Antifungal activity of Zinc nitrate derived nano Zno fungicide synthesized from Trachyspermum ammi to control fruit rot disease of grapefruit.

Grapefruit (Citrus paradisi) is a widely grown citrus and its fruit is affected by a variety of biotic and abiotic stress. Keeping in view the hazardous effects of synthetic fungicides, the recent trend is shifting towards safer and eco-friendly control of fruit diseases. The present study was aimed to diagnose the fruit rot disease of grapefruit and its control by using zinc oxide green nanoparticles (ZnO NPs). Fruit rot symptoms were observed in various grapefruit growing sites of Pakistan. Diseased samples were collected, and the disease-causing pathogen was isolated. Following Koch's postulates, the isolated pathogen was identified as Rhizoctonia solani. For eco-friendly control of this disease, ZnO NPs were prepared in the seed extract of Trachyspermum ammi and characterized. Fourier transform infrared spectroscopy (FTIR) of these NPs described the presence of stabilizing and reducing compounds such as phenols, aldehyde and vinyl ether, especially thymol (phenol). X-ray diffraction (XRD) analysis revealed their crystalline nature and size (48.52 nm). Energy dispersive X-ray (EDX) analysis elaborated the presence of major elements in the samples, while scanning electron microscopy (SEM) confirmed the morphology of bio fabricated NPs. ZnO NPs exhibited very good anti-fungal activity and the most significant fungal growth inhibition was observed at 1.0 mg/ml concentration of green NPs, in vitro and in vivo. These findings described that the bioactive constituents of T. ammi seed extract can effectively reduce and stabilize ZnO NPs. It is a cost-effective method to successfully control the fruit rot disease of grapefruit.

Scanning electron microscopy of bio-fabricated Fe2 O3 nanoparticles and their application to control brown rot of citrus.

Citrus is the leading fruit crop of Pakistan and exported to different parts of the world. Due to suitable weather condition, this crop is affected by different biotic factors which seriously deteriorate its quality and quantity. During the months of November 2018 to January 2019, citrus brown rot symptoms were recurrently observed on sweet oranges in National Agricultural Research Centre (NARC), Islamabad. Causal agent of citrus brown rot was isolated, characterized, and identified as Fusarium oxysporum. For environment-friendly control of this disease, leaf extract of Azadirachta indica was used for the green synthesis of iron oxide (Fe2 O3 ) nanoparticles. These nanoparticles were characterized before their application for disease control. Fourier transform infrared spectroscopy (FTIR) of these synthesized nanoparticles described the presence of stabilizing and reducing compounds like alcohol, phenol, carboxylic acid, and alkaline and aromatic compounds. X-Ray diffraction (XRD) analysis revealed the crystalline nature and size (24 nm) of these nanoparticles. Energy dispersive X-Ray (EDX) analysis elaborated the presence of major elements in the samples. Scanning electron microscopy (SEM) confirmed the spinal shaped morphology of prepared nanoparticles. Successfully synthesized nanoparticles were evaluated for their antifungal potential. Different concentrations of Fe2 O3 nanoparticles were used and maximum mycelial inhibition was observed at 1.0 mg/ml concentration. On the basis of these findings, it could be concluded that Fe2 O3 nanoparticles, synthesized in the leaf extract of A. indica, can be successfully used for the control of brown rot of sweet oranges.

Deciphering metal toxicity responses of flax (Linum usitatissimum L.) with exopolysaccharide and ACC-deaminase producing bacteria in industrially contaminated soils.

Rapid industrialization is the main reason of heavy metals contamination of soil colloids and water reservoirs. Heavy metals are persistent inorganic pollutants; deleterious to plants, animals and human beings because of accumulation in food chain. The aim of the current work was to evaluate the role of indole acetic acid (IAA), exopolysaccharide (EPS) and ACC-deaminase producing plant growth promoting rhizobacteria (PGPR) i.e .B. gibsonii PM11 and B. xiamenensis PM14 in metal phytoremediation of metals, their survival and plant growth promotion potential in metal polluted environment as well as alterations in physio-biochemical responses of inoculated L. usitatissimum plants towards heavy metal toxicity. Two bacterial strains Bacillus gibsonii (PM11) and Bacillus xiamenensis (PM14), previously isolated from sugarcane's rhizosphere, were screened for metal tolerance (50 mg/l to 1000 mg/l) and plant growth promoting traits like IAA, ACC-deaminase, EPS production and nitrogen fixing ability under metal stress. The response of flax plant (Linum usitatissimum L.) was analyzed in a pot experiment containing both industrially contaminated and non-contaminated soils. Experiment was comprised of six different treatments, each with three replicates. At the end of the experiment, role of metal tolerant plant growth promoting bacterial inoculation was elucidated by analyzing the plant growth parameters, chlorophyll contents, antioxidative enzymes, and metal uptake both under standard and metal contaminated rhizospheres. Results revealed that root and shoot length, plant's fresh and dry weight, proline content, chlorophyll content, antioxidant enzymatic activity was increased in plants inoculated with plant growth promoting bacteria as compared to non-inoculated ones both in non-contaminated and industrial contaminated soils. In current study, inoculation of IAA, EPS and ACC-deaminase producing bacteria enhances plant growth and nutrient availability by minimizing metal-induced stressed conditions. Moreover, elevated phytoextraction of multi-metals from industrial contaminated soils by PGPR inoculated L. usitatissimum plants reveal that these strains could be used as sweepers in heavy metals polluted environment.

Multi-stress tolerant PGPR Bacillus xiamenensis PM14 activating sugarcane (Saccharum officinarum L.) red rot disease resistance.

Sustainability in crop production has emerged as one of the most important concerns of present era's agricultural systems. Plant growth promoting bacteria (PGPB) has been characterized as a set of microorganisms used for enhancing plant growth and a tool for biological control of phytopathogens. However, the inconsistent performance of these bacteria from laboratory/greenhouse to field level has emerged due to prevailing abiotic stresses in fields. Sugarcane crop encounters a combination of biotic and abiotic stresses during its long developmental stages. Nevertheless, the selection of antagonistic PGPB with abiotic stress tolerance would be beneficial for end-user by the successful establishment of product with required effects under field conditions. Stress tolerant Bacillus xiamenensis strain (PM14) isolated from the sugarcane rhizosphere grown in the fields was examined for various PGP activities, enzyme assays, and antibiotic resistance. Strain was screened for in vitro tolerance against drought, salinity, heat stress, and heavy metal toxicity. Inhibition co-efficient of B. xiamenensis PM14 was also calculated against six phyto-pathogenic fungi, including Colletotrichum falcatum (53.81), Fusarium oxysporum (68.24), Fusarium moniliforme (69.70), Rhizoctonia solani (71.62), Macrophomina phaseolina (67.50), and Pythium splendens (77.58). B. xiamenensis is reported here for the first time as the rhizospheric bacterium which possesses resistance against 12 antibiotics and positive results for all in vitro PGP traits except HCN production. Role of 1-aminocyclopropane-1-carboxylate deaminase in the amelioration of biotic and abiotic stress was also supported by the amplification of acds gene. Moreover, in vitro and in vivo experiments revealed B. xiamenensis as the potential antagonistic PGPR and bio-control agent. Results of greenhouse experiment against sugarcane red rot indicated that inoculation of B. xiamenensis to sugarcane plants could suppress the disease symptoms and enhance plant growth. Augmented production of antioxidative enzymes and proline content may lead to the induced systemic resistance against red rot disease of sugarcane. Thus, the future application of native multi-stress tolerant bacteria as bio-control agents in combination with current heat, drought, salinity, and heavy metal tolerance strategy could contribute towards the global food security.

Residual effects of biochar and phosphorus on growth and nutrient accumulation by maize (Zea mays L.) amended with microbes in texturally different soils.

The purpose of study was to examine the residual effects of two types of biochar amendments, two phosphorus (P) fertilizer levels, phosphorus solubilizing bacteria (PSB) and arbuscular mycorrhizal fungs (AMF) on plant growth, nutrients absorption and root architecture of Zea mays L. in texturally different soils. Biochar signficantly increased nutrients absorption and plant biomass production with P-fertilization and microbial inoculantion. Texturally different soils enhanced the plant biomass and nutrients absorption in their independent capacity on addition of biochar, microbial inoculants and P-fertilization. It was shown that mycorrhizal inoculation had positive influence on plant root and shoot biomass in both soils irrespective to the biochar type used. Root colonization was notably increased in biochar + mycorrhizae (B + M) inocultaed plants. It was shown that mycorrhizal inoculation had positive influence on nutrients absorption by plant roots and it had high content of P, potassium, calcium and magnesium in plants at all biochar and P levels. Without P fertilization, biochar amendments significantly promoted shoot P content and root colonization. The P application significantly influenced soil microbial activity in terms of nutrient concentration and plant growth. Root attributes were significantly inclined by microbial inoculation. Residual effects of biochar and P significantly enhanced the nutreints absorption and maize plant growth. Thus, we concluded that residual biochar and P fertilizer showed positive effects on nutrients absorption and maize plant growth promotion in differently textured soils. Microbial inoculants further stimulated the plant biomass production and nutrients absorption due to effective root colonization.

Assisted phytoremediation of chromium spiked soils by Sesbania Sesban in association with Bacillus xiamenensis PM14: A biochemical analysis.

Due to anthropogenic activities, chromium (Cr) contamination is ubiquitous with deleterious effects on plant and soil microbiota. Present study was designed to address beneficial effects of Bacillus xiamenensis PM14 on Sesbania sesban. Its physiological and biochemical attributes along with enhanced antioxidant enzyme activities under different levels of Cr toxicity (50, 100 and 200 mg kg-1) were evaluated. After harvesting at 50 days of sowing, plant growth attributes (root and shoot length, fresh and dry weight), physiological parameters (chlorophyll a, b and carotenoid content), antioxidant activities (superoxide dismutase, peroxidase and catalase), malondialdehyde content, electrolyte leakage, proline, relative water content and total Cr uptake in S. sesban were recorded. Experiment was statistically managed as complete randomized design (CRD). Results revealed that Cr stress reduced plant growth, relative water content at all levels of Cr contamination. However, inoculation of B. xiamenensis PM14 positively influence all parameters of S. sesban both under normal and stressed conditions. Inoculation of B. xiamenensis PM14 promoted plant growth (root length 17.08%, shoot length 28.36%) physiological attributes (chlorophyll a 55.26%, chlorophyll b 59.13%), antioxidant activities (superoxide dismutase 30.09%, peroxidase 6.96% and catalase 0.89%), relative water content 25.79%, enhanced total Cr uptake 47.33% and reduced proline 12.33%, malondialdehyde content 27.53% and electrolyte leakage 2.73% in S. sesban at 200 mg kg-1 Cr stress as compared to uninoculated plants grown under the same level of Cr. Our findings revealed first report of B. xiamenensis as phytoremediator and its inoculation on Sesbania plant. It also exposed dual effects of B. xiamenensis to ameliorate Cr stress along with improved plant growth and induced heavy metal stress tolerance in spiked soils.

Mechanistic elucidation of germination potential and growth of wheat inoculated with exopolysaccharide and ACC- deaminase producing Bacillus strains under induced salinity stress.

The potential of plant growth regulating microorganisms present in the soil can be explored towards the purpose of identifying salt tolerant strategies and crop cultivars. Current study was designed to elucidate the capabilities of salt stress tolerant plant growth promoting rhizobacteria (PGPR) Bacillus siamensis (PM13), Bacillus sp. (PM15) and Bacillus methylotrophicus (PM19) in undermining the effects of salt stress on wheat seedling. Strains were characterized for their IAA (81-113 µM/ml), ACC-deaminase (0.68-0.95 µM/mg protein/h) and exopolysaccharide (EPS) (0.62-0.97 mg/ml) producing activity both under normal and NaCl stressed conditions. Effects of bacterial inoculation on germination and seedling growth of wheat variety Pakistan-13 was observed under induced salinity stress levels (0, 4, 8, 16 dS/m). All the morpho-physiological characteristics of wheat seedlings were affected drastically by the NaCl stress and the growth parameters expressed a negative relationship with increased NaCl levels. PGPR application had a very positive influence on germination rate of wheat seedlings, root and shoot length, photosynthetic pigments etc. Elongated roots and enhanced vegetative shoot growth as well as seedling's fresh and dry weights were highest in plants treated with B. methylotrophicus PM19. Sequestration of Na+ ion by EPS production and degradation of exuded ACC into a-ketobutyrate and ammonia by ACCD bacteria efficiently reduced the impact of salinity stress on wheat growth. Current findings suggested that the used PGPR strains are potential candidates for improving crop growth in salt stressed agricultural systems. However further research validation would be necessary before large scale/field application.