Harnessing Walnut-Based Zinc Oxide Nanoparticles: A Sustainable Approach to Combat the Disease Complex of Meloidogyne arenaria and Macrophomina phaseolina in Cowpea

Zinc oxide nanoparticles (ZnO NPs) exhibit diverse applications, including antimicrobial, UV-blocking, and catalytic properties, due to their unique structure and properties. This study focused on the characterization of zinc oxide nanoparticles (ZnO NPs) synthesized from Juglans regia leaves and their application in mitigating the impact of simultaneous infection by Meloidogyne arenaria (root-knot nematode) and Macrophomina phaseolina (root-rot fungus) in cowpea plants. The characterization of ZnO NPs was carried out through various analytical techniques, including UV-visible spectrophotometry, Powder-XRD analysis, FT-IR spectroscopy, and SEM-EDX analysis. The study confirmed the successful synthesis of ZnO NPs with a hexagonal wurtzite structure and exceptional purity. Under in vitro conditions, ZnO NPs exhibited significant nematicidal and antifungal activities. The mortality of M. arenaria juveniles increased with rising ZnO NP concentrations, and a similar trend was observed in the inhibition of M. phaseolina mycelial growth. SEM studies revealed physical damage to nematodes and structural distortions in fungal hyphae due to ZnO NP treatment. In infected cowpea plants, ZnO NPs significantly improved plant growth parameters, including plant length, fresh mass, and dry mass, especially at higher concentrations. Leghemoglobin content and the number of root nodules also increased after ZnO NP treatment. Additionally, ZnO NPs reduced gall formation and egg mass production by M. arenaria nematodes and effectively inhibited the growth of M. phaseolina in the roots. Furthermore, histochemical analyses demonstrated a reduction in oxidative stress, as indicated by decreased levels of reactive oxygen species (ROS) and lipid peroxidation in ZnO NP-treated plants. These findings highlight the potential of green-synthesized ZnO NPs as an eco-friendly and effective solution to manage disease complex in cowpea caused by simultaneous nematode and fungal infections.

Synthesis, characterization and antifungal potential of titanium dioxide nanoparticles against fungal disease (Ustilago tritici) of wheat (Triticum aestivum L.)

Nanoparticles (NPs) preparation using a green as well as environmentally acceptable processes has achieved a lot of attention in recent decade. The current study compared the synthesis of titania (TiO₂) nanoparticles synthesized from leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) and traditional approach by chemical preparation. The effects of no calcination on the physical characteristics of TiO₂ NPs as well as their antifungal effects were examined and compared with the already reported calcinated TiO₂ NPs. The produced TiO₂ NPs were evaluated using high-tech techniques such as X-ray diffraction (XRD), scanning electron microscope, energy dispersive spectroscopy (EDX), and elemental mapping. TiO₂ NPs prepared by sol-gel technique (T1) and prepared from extractions from leaves of T. portulacastrum (T2), and C. quinoa (T3) were either calcinated or non calcinated and tested against fungal disease (Ustilago tritici) of wheat for antifungal efficacy. The -peak (2θ) at 25.3 was confirmed by XRD to be connected with the anatase (101) form in both cases but before calcination, NPs were lacking the rutile and brookite peaks. The results showed that all types of TiO₂ NPs examined had good antifungal activity against U. tritici, but those made from C. quinoa plant extract have good antifungal activity against disease. TiO₂ NPs which are produced by the green methods (T2, T3) have the highest antifungal activity (58%, 57% respectively), while minimal activity (19%) was recorded when NPs were synthesized using the sol-gel method (T1) with 25 μl/mL. Non calcinated TiO₂ NPs have less antifungal potential than calcined TiO₂ NPs. It can be concluded that calcination may be preferred for efficient antifungal activity when using titania nanoparticles. The green technology may be used on a larger scale with less damaging TiO₂ NP production and can be utilized against fungal disease on wheat crop to reduce crop losses worldwide.

Acrophialophora jodhpurensis: an endophytic plant growth promoting fungus with biocontrol effect against Alternaria alternata

In this study, efficiency of the endophytic fungal isolate Msh5 was evaluated on promoting tomato plant growth and controlling Alternaria alternata, the causal agent of early blight in tomatoes. Morphological and molecular (ITS and tub2 sequences) analyses revealed that the fungal isolate, Msh5, was Acrophialophora jodhpurensis (Chaetomium jodhpurense Lodha). This beneficial fungus was capable of producing indole-3-acetic acid (IAA), urease, siderophore, extracellular enzymes, and solubilized phosphate. Under laboratory conditions, the Msh5 isolate of A. jodhpurensis inhibited A. alternata growth in dual culture, volatile and non-volatile metabolites assays. The supernatant of this endophytic fungus was capable of reducing spore germination and altering the hyphal structure of A. alternata and the spores produced germ tubes showed vacuolization and abnormal structure compared to the control. Also, the effect of A. jodhpurensis on plant growth parameters (such as shoot and root weight and length) and suppressing A. alternata was investigated in vivo via seed inoculation with spores of A. jodhpurensis using 1% sugar, 0.5% carboxymethyl cellulose (CMC) or 0.5% molasses solution as stickers. Colonization of tomato roots by the endophytic fungus resulted in significant increasing plant growth parameters and reduction in the progress of the diseases caused by A. alternata compared to the controls. Among the different coating materials used as stickers, sugar was found to be the most effective for enhancing plant growth parameters and decreasing the disease progress. Therefore, A. jodhpurensis isolate Msh5 can be suggested as a potential biofertilizer and biocontrol agent for protecting tomato plants against A. alternata.

Assessment of Plant Extracts and their In vitro Efficacy against Potato Early Blight Incited by Alternaria solani

Botanicals obtained from the plants are well known for the suppression of inimical plant pathogens. The present study explores the efficacy of five locally available plant extracts for their antifungal activity against the early blight of potato incited by Alternaria solani. The extracts include Datura stramonium, Allium sativum, Azadirachta indica, Eucalyptus globulus, and Lantana camara. All extracts reduced mycelial growth and conidial germination of A. solani. In vitro studies showed that extracts obtained from A. sativum and A. indica have significant inhibition of mycelial growth of A. solani (88.80 and 86.62 percent) at 20 percent concentration. Higher concentrations of A. sativum extract caused a higher reduction of A. solani radial growth on potato dextrose agar medium. Extracts obtained from A. sativum and A. indica at 20 percent concentration, were found most effective for inhibition of conidial germination (85.50 and 80.04 percent) respectively of A. solani. Observations by scanning electron microscope (SEM) showed dramatic alteration in A. solani hyphae collapsed and spores shrinked when treated with extract of A. sativum at a 20 per cent concentration. The qualitative and quantitative analysis of various phytochemicals like flavonoids, alkaloids, saponins, tannins, steroids, terpenoids, glycosides, and phenols was showed A. sativum extract better than all the other plant extracts. Observation also revealed that 20 percent concentration of garlic extract has potential to inhibit to A. solani.

Novel Prosopis juliflora leaf ethanolic extract as natural antimicrobial agent against food spoiling microorganisms

Fresh produces spoilage is a worldwide concern that accompany the global increase in food demand. Adverse human health and environmental effects of commercial spoilage control agents are major public concern. In this study, Prosopis juliflora leaves and fruit extracts had their antimicrobial activities evaluated against the growth of selected bacteria and yeast, and against mycelial growth and conidial germination of selected mycotoxins-producing fungi. P. juliflora water-soluble leaf ethanolic (PJ-WS-LE) extract with its novel extraction method showed the strongest antibacterial activity. Antimicrobial tests showed total inhibition of Botrytis cinerea, Alternaria alternata, Bacillus subtilis, Staphylococcus aureus and Candida albicans with MICs ranging between 0.125 and 1 mg/ml. Percent inhibition of mycelial growth (PIMG) of the extract was also determined against seven other fungal strains with highest value against Geotrichum candidum (66.2%). Even the least affected fungal strain showed alterations in their hyphae and spores exposed to PJ-WS-LE extract when observed using scanning electron microscope (SEM), alterations include exfoliated flakes, pores, vacuolation and applanation. Small-scale fruit bioassays controlled experiment showed high efficacy of the extract in protecting inoculated cherry tomato samples from B. cinerea and A. alternata infections. In conclusion, PJ-WS-LE extract is a feasible, natural antifungal agent that can replace common anti-spoiling chemicals.

Synthesis and characterization of titanium dioxide nanoparticles by chemical and green methods and their antifungal activities against wheat rust

The production of metallic nanoparticles (NPs) by green and ecofriendly methods has received consideration during the recent past. The present study summarized the comparative production of titanium dioxide (TiO₂) NPs by plant extracts of Trianthema portulacastrum (T2) and Chenopodium quinoa (T3) and by conventional chemical (sol-gel) method (T1). Synthesized TiO₂-NPs were examined by high-tech. techniques such as X-Ray Diffraction (XRD), Fourier Transmission Infra-red (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) spectroscope, SEM-EDS spot analysis and elemental mapping. Synthesized TiO₂-NPs were applied on wheat rust (Ustilago tritici) for the evaluation of their antifungal activity against toxic plant pathogens. XRD results confirmed the (2θ) peak at 25.3 related to 101 anatase form. EDS-spot analysis and elemental mapping confirms the formation of TiO₂-NPs by using these techniques. SEM secondary electrons (SEs) images demonstrated the nano range of particles in cluster form with fewer porous structures. The average size of all three TiO₂-NPs was found less than 15 nm. FT-IR analysis of all three TiO₂-NPs perfectly matched with the standard parameters. The NPs prepared by both sol-gel and green methods have a good antifungal response against U. tritici, and the green prepared TiO₂-NPs were found to have the best antifungal activity against wheat rust especially NPs synthesized with the extract of C. quinoa. Overall, green method can be used for the large scale and less toxic synthesis of TiO₂-NPs because of their wide range of environmental applications.