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Introduction: Chemo- and bio-genic metallic nanoparticles (NPs), as a novel nano-enabled strategy, have demonstrated a great potential in crop health management. Objective: The current study aimed to explore the efficacy of advanced nanocomposites (NCs), integrating biogenic (bio) metallic NPs and plant immunity-regulating hormones, in crop disease control. Methods: Iron (Fe) NPs were biosynthesized using cell-free supernatant of a Fe-resistant strains, Bacillus marisflavi ZJ-4. Further, salicylic acid-coated bio-FeNPs (SI) NCs were prepared via co-precipitation method under alkaline conditions. Both bio-FeNPs and SINCs were characterized using basic analytical techniques, including Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis, and scanning/transmission electron microscopy. Results: Bio-FeNPs and SINCs had variable shapes with average sizes of 72.35 nm and 65.87 nm, respectively. Under greenhouse conditions, bio-FeNPs and SINCs improved the agronomic traits of the watermelon plants, and SINCs outperformed bio-FeNPs, providing the maximum growth promotion of 32.5%. Soil-drenching with bio-FeNPs and SINCs suppressed Fusarium oxysporum f. sp. niveum-caused Fusarium wilt in watermelon, and SINCs provided better protection than bio-FeNPs, through inhibiting the fungal invasive growth within host plants. SINCs improved the antioxidative capacity and primed a systemic acquired resistance (SAR) response via activating the salicylic acid signaling pathway genes. These findings indicate that SINCs can reduce the severity of Fusarium wilt in watermelon by modulating antioxidative capacity and potentiating SAR to restrict in planta fungal invasive growth. Conclusion: This study provides new insights into the potential of bio-FeNPs and SINCs as biostimulants and bioprotectants for growth promotion and Fusarium wilt suppression, ensuring sustainable watermelon production.

Green nanomaterials have gained much attention due to their potential use as therapeutic agents. The present study investigated the production of silver nanoparticles (AgNPs) from a silver-resistant Bacillus safensis TEN12 strain, which was isolated from metal contaminated soil and taxonomically identified through 16S rRNA gene sequencing. The formation of AgNPs in bacterial culture was confirmed by using UV–vis spectroscopy with an absorption peak at 426.18 nm. Fourier transform infrared (FTIR) spectroscopy confirmed the involvement of capping proteins and alcohols for stabilization of AgNPs. Moreover, X-ray diffraction analysis (XRD), scanning and transmission electron microscopy (SEM and TEM) confirmed the crystalline nature and spherical shape of AgNPs with particle size ranging from 22.77 to 45.98 nm. The energy dispersive X-ray spectroscopy (EDX) revealed that 93.54% silver content is present in the nano-powder. AgNPs showed maximum antibacterial activity (20.35 mm and 19.69 mm inhibition zones) at 20 µg mL−1 concentration against Staphylococcus aureus and Escherichia coli, respectively and significantly reduced the pathogen density in broth culture. Furthermore, AgNPs demonstrated significant anticancer effects in the human liver cancer cell line (HepG2) in MTT assay, whereas, no cytotoxic effects were demonstrated by AgNPs on normal cell line (HEK293). The present study suggests that the biogenic AgNPs may substitute chemically synthesized drugs with wider applications as antibacterial and anticancer agents.

Dereplication of crude plant extracts through liquid chromatography-mass spectrometry is a powerful technique for the discovery of novel natural products. Unfortunately, this technique is often plagued by a low level of confidence in natural product identification. This is mainly due to the lack of extensive chromatographic and mass spectrometric optimizations that result in improper and incomplete MS/MS fragmentation data. This study proposes a solution to this problem by the optimization of chromatographic separation and mass spectrometry parameters. We report herein a direct and high-throughput strategy for natural product dereplication in five Salvia species using high-resolution ESI-QTOF-MS/MS data. In the present study, we were able to identify a total of forty-seven natural products in crude extracts of five Salvia species using MS/MS fragmentation data. In addition to dereplication of Salvia species, quantitative profiling of twenty-one bioactive constituents of the genus was also performed on an ion trap mass spectrometer. For the quantitation study, method development focused on chromatographic optimizations to achieve maximum sensitivity. The developed dereplication and quantitation strategy can be extended to develop comprehensive metabolic profiles of other plant genera and species and thus can prove useful in the field of drug discovery from plants.