Nadiyah M. Alabdallah

Summary statement: The study identifies a phosphorylation‐dependent calcium signalling module, PuCBL9–PuCIPK11, that remodels the guard‐cell actin cytoskeleton in Populus ussuriensis to accelerate stomatal closure. This work bridges a long‐standing gap between calcium decoding and cytoskeletal dynamics in trees, and opens a new translational avenue for forest improvement.

Due to the indiscriminate use of antimicrobial drugs in the treatment of infectious diseases, human pathogenic bacteria have developed resistance to many commercially available antibiotics. Medicinal plants such as Convolvulus arvensis represent a renewable resource for the development of alternative therapeutic agents. This study aimed to evaluate the antibacterial activity of silver nanoparticles (AgNPs) biosynthesized from C. arvensis against two clinical antibiotic-resistant bacterial isolates. The pathogenic isolates were identified as Staphylococcus aureus MRSA and Escherichia coli ESBL using 16S rRNA gene sequencing. Silver nanoparticles were synthesized via a green synthesis approach, and their physicochemical properties were characterized using UV–Vis spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, zeta potential, and dynamic light scattering (DLS). The synthesized C. arvensis–AgNPs exhibited a surface plasmon resonance peak at 475 nm and predominantly spherical morphology with particle sizes ranging from 102.34 to 210.82 nm. FTIR analysis indicated the presence of O–H, C–O, C–N, C–H, and amide functional groups. The nanoparticles showed a zeta potential of −18.9 mV and an average hydrodynamic diameter of 63 nm. The antibacterial activity of the biosynthesized AgNPs was evaluated against methicillin-resistant S. aureus (MRSA and ATCC 29213) and E. coli (ESBL and ATCC 25922) using agar diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. Inhibition zones ranged from 10 to 13 mm, with MIC and MBC values of 12.5–25 µg/mL and 25–50 µg/mL, respectively. In addition, the nanoparticles exhibited antioxidant activity (DPPH assay, IC₅₀ = 0.71 mg/mL) and anti-inflammatory effects as determined by protein denaturation inhibition. No cytotoxic effects were observed in the MCF-7 cell line at the MIC level. These findings suggest that C. arvensis–AgNPs have potential as natural antimicrobial, antioxidant, and anti-inflammatory agents.

Silver nanoparticles (AgNPs) have emerged as promising agents for enhancing plant growth and physiological functions in recent years. However, their role in alleviating salt-induced stress in plants is not yet well understood. In this study, we investigated the impact of foliar sprays of AgNPs1 (300 ppm) and AgNPs2 (400 ppm) on the morphological, physiological, and biochemical responses of chickpea ( Cicer arietinum L.) seedlings subjected to different levels of salt stress. The chickpea plants were treated with seawater concentrations of 10%, 30%, and 50%, inducing mild, moderate, and severe salt stress. Salt stress significantly inhibited the growth of chickpea, resulting in reductions in both fresh and dry biomass. Additionally, salinity-induced oxidative stress was indicated by elevated malondialdehyde (MDA) levels in chickpea leaves. However, AgNPs, whether applied alone or in combination with salt stress, enhanced several physiological parameters, including chlorophyll content, chlorophyll stability index (CSI), chlorophyll fluorescence (Fv/Fm), and proline levels, while reducing TSS and MDA levels. Moreover, the antioxidant enzyme activity in chickpea leaves improved under salt stress when AgNPs (AgNPs1 and AgNPs2) were applied, suggesting that AgNPs play a key role in mitigating oxidative damage and promoting stress tolerance. Taken together, these results indicate that applying AgNPs can improve the salinity tolerance of chickpea seedlings by enhancing their morphological, physiological, and biochemical responses to salt stress, offering a potential solution for boosting crop yields on salt-affected soils globally.

Nanotechnology plays a vital role in enhancing plant tolerance to salt stress; however, comparative studies on zinc oxide bulk particles (ZnO bulk) and zinc oxide nanoparticles (ZnO NPs) in this context remain unexplored. Since zinc (Zn) is an essential micronutrient involved in enzyme activation, photosynthesis, and antioxidant responses, it is important to understand how ZnO bulk and ZnO NPs influence chickpea growth under salt stress. This study investigated the morphological and physiological responses of chickpea seedlings treated with ZnO bulk (50 mg/L) and ZnO NPs (50 mg/L) under varying salt concentrations (20, 40, 80, and 120 mmol/L). Salt stress significantly inhibited chickpea growth, reducing the relative growth rate, net assimilation rate, total chlorophyll content, and potassium (K) and zinc ion levels while increasing sodium (Na), chlorine (Cl), malondialdehyde (MDA), and proline content. However, the application of ZnO bulk and ZnO NPs improved these parameters, mitigating the negative effects of salt stress. Furthermore, exogenous ZnO bulk and ZnO NPs to salt-stressed (20, 40, 80, and 120 mmol/L) chickpea resulted in decreased malondialdehyde content by 30, 32, 47, 34%, and 58, 31, 48, 47%, proline content by 4, 6, 1.6, 4% and 22, 21, 22, 28%, respectively, in comparison to the control. Notably, ZnO bulk and ZnO NPs enhanced antioxidant enzyme activities, including superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, and glutathione reductase. These findings suggest that foliar application of ZnO bulk and ZnO NPs helps alleviate salt stress in chickpeas, promoting better growth and physiological performance under saline conditions.

Background: Breast cancer and chronic bacterial infections are pressing global health issues, and traditional treatments are often hampered by resistance and adverse side effects. This study sought to create silver nanoparticles (AgNPs) through eco-friendly synthesis using Hibiscus rosa sinensis (HRS) flower extract and to assess their antibacterial, antibiofilm, and anticancer properties. Methods: HRS extract functioned as both a reducing and stabilizing agent in the synthesis of AgNPs. The nanoparticles were characterized using ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Antibacterial and antibiofilm properties were evaluated against gram-positive (Staphylococcus aureus and Enterococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria using agar well diffusion and XTT reduction assays. The cytotoxic effects on MDMB-231 breast cancer cells and normal splenocytes were measured using the MTT assay, whereas fluorescence microscopy was used to observe reactive oxygen species (ROS) production, changes in mitochondrial membrane potential, and caspase-3 activation. Results: The synthesized HRS-AgNPs, primarily ranging from 10 to 50 nm, displayed a distinct surface plasmon resonance (SPR) peak at 428 nm. They exhibit notable antibacterial activity, especially against gram-positive bacteria, and effectively disrupt bacterial biofilms. Cytotoxicity evaluations showed that HRS-AgNPs decreased the viability of MDMB-231 cells in a dose-dependent manner, with minimal toxicity observed in normal splenocytes. The increase in ROS levels, reduction in mitochondrial membrane potential, and heightened caspase-3 activity collectively suggest apoptosis-driven cell death in cancer cells. Conclusions: HRS-AgNPs demonstrated dual functionality, with strong antibacterial and selective anticancer effects. Their environmentally friendly synthesis, stability, and significant biological activities suggest their potential for further development, including in vivo safety and efficacy assessments for clinical applications in treating infections and breast cancer.