Delia Luca

Climate change is placing global agriculture under growing pressure, as plants must withstand extreme environmental conditions such as drought and high salinity, both inducing osmotic and oxidative stress. As part of their survival strategies, plants accumulate protective molecules (osmolytes), including the amino acid proline. For decades, plant biology has largely assumed that high proline accumulation under stress signals strong stress tolerance. However, this review challenges that “proline-centric” perspective. Analyses across a wide range of plant species reveal a more complex picture. Stress-induced proline accumulation is not universal: in some species, proline levels remain relatively unchanged, with other metabolites acting as functional osmolytes, or increase only in response to artificially applied severe stress conditions. Even when proline increases, its absolute concentrations may be too low to contribute significantly to osmotic adjustment. Nevertheless, proline may still be involved in stress tolerance mechanisms through its additional roles, detoxifying reactive oxygen species (ROS), directly stabilising proteins or acting as a stress signalling molecule. Comparative analyses of genetically related taxa with varying degrees of stress tolerance sometimes show negative correlations between proline accumulation and tolerance, with higher proline concentrations measured in the most sensitive genotypes. Overall, the evidence indicates that proline‘s role in plant survival is highly context-dependent and strongly influenced by genetic background and must therefore be evaluated on a case-by-case basis. Distinguishing whether proline acts as an adaptive defence or merely as a biochemical marker of physiological strain under stress is essential for accurately assessing plant stress tolerance.

In this study, a simple, cost-effective, and eco-friendly approach was developed for the synthesis of AgNPs using white (Muscat Ottonel, WGPE) and red (Cabernet Sauvignon, RGPE) grape pomace extracts. The AgNPs were characterized by SEM, AFM, DLS, UV–Vis, FTIR, and XPS techniques. Their formation was initially indicated by a color change from colorless to dark brown and confirmed by the appearance of an SPR peak at 445 nm. The AgNPs are predominantly spherical with varied sizes. FTIR and XPS analyses indicated the presence of oxygen- and nitrogen-containing functional groups on the nanoparticle surface, suggesting their involvement in the reduction of Ag⁺ ions and the stabilization of the synthesized AgNPs. The biological activity of AgNPs was assessed through wheat (Triticum aestivum L.) seed priming experiments. Treatment with 25 mg/L AgNPs (WGPE) significantly enhanced seedling growth and chlorophyll content, whereas exposure to 100 mg/L AgNPs (RGPE) induced oxidative stress and negatively affected growth parameters. Furthermore, the photocatalytic activity of both AgNPs was evaluated against MB degradation under visible light irradiation. AgNPs (WGPE) showed superior photocatalytic efficiency, achieving up to 77% dye removal within 240 min and a constant rate nearly three times higher than that of AgNPs (RGPE). The photodegradation process was mainly driven by ^•OH radicals. Our results highlight the potential of biosynthesized AgNPs for agricultural applications and wastewater remediation.

Climate change is placing global agriculture under growing pressure, as plants must withstand extreme environmental conditions such as drought and high salinity, both inducing osmotic and oxidative stress. As part of their survival strategies, plants accumulate protective molecules (osmolytes), including the amino acid proline. For decades, plant biology has largely assumed that high proline accumulation under stress signals strong stress tolerance. However, this review challenges that “proline-centric” perspective. Analyses across a wide range of plant species reveal a more complex picture. Stress-induced proline accumulation is not universal: in some species, proline levels remain relatively unchanged, with other metabolites acting as functional osmolytes, or increase only in response to artificially applied severe stress conditions. Even when proline increases, its absolute concentrations may be too low to contribute significantly to osmotic adjustment. Nevertheless, proline may still be involved in stress tolerance mechanisms through its additional roles, detoxifying reactive oxygen species (ROS), directly stabilising proteins or acting as a stress signalling molecule. Comparative analyses of genetically related taxa with varying degrees of stress tolerance sometimes show negative correlations between proline accumulation and tolerance, with higher proline concentrations measured in the most sensitive genotypes. Overall, the evidence indicates that proline’s role in plant survival is highly context-dependent and strongly influenced by genetic background and must therefore be evaluated on a case-by-case basis. Distinguishing whether proline acts as an adaptive defence or merely as a biochemical marker of physiological strain is essential for accurately assessing plant stress tolerance.

This review aims to explore the green synthesis of metal and metal oxide nanoparticles using various species of the genus Artemisia. The synthesis processes commonly involve aqueous or organic extracts of plant parts (e.g., leaves, stems, and roots), which react with metal salt solutions (e.g., AgNO₃, Zn(NO₃)₂, HAuCl₄, Cu(NO₃)₂) under controlled parameters, including pH, temperature, and light exposure. The synthesized nanoparticles are characterized using techniques such as UV–Visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential analysis. These approaches provide information on nanoparticle size, morphology, crystallinity, surface chemistry and charge, which are significantly influenced by synthesis parameters and the specific Artemisia species used. The biosynthesized nanoparticles have demonstrated promising multifunctional applications, including broad-spectrum antimicrobial activity against bacterial and fungal strains, antioxidant capacity, anticancer potential, as well as applications in agriculture and environmental remediation.

Silver nanoparticles, with various uses in pharmacy, cosmetics, sanitation, textiles, optoelectronics, photovoltaics, etc., that are provided by worldwide industrial production, estimated to hundreds of tons annually, are finally released in the environment impacting randomly the biosphere. An alternative synthesis approach could be implemented by replacing chemical reductants of silver with natural antioxidants ensuring production and utilization sustainability with focus on environmental pollution diminishing. We synthesized silver nanoparticles by using plant extracts, aiming to offer antimicrobial products with reduced impact on the environment through sustainable green-chemistry. Fresh extracts of lemon pulp, blueberry and blackberry fruits as well as of green tea dry leaves were the sources of the natural antioxidants able to ensure ionic silver reduction and silver nanoparticle formation in the form of colloidal suspensions. The four samples were characterized by UV–Vis spectrophotometry, scanning electron microscopy, dark field optical microscopy, X-ray diffractometry, dynamic light scattering, which evidenced specific fine granularity, plasmonic features, standard crystallinity, and good stability in water suspension. Antimicrobial activity was assayed using the agar diffusion method and the bacteria kill-time technique against Staphylococcus aureus and Escherichia coli. In both cases, all silver nanoparticles revealed their adequacy for the aimed purposes, the sample synthesized with green tea showing the best efficiency, which is in concordance with its highest contents of polyphenols, flavones and best total antioxidant activity. Various applications could be safely designed based on such silver nanoparticles for sustainable chemistry development.