Rapid fruit softening, weight loss and pathogen infection induced by mechanical wound are major factors causing postharvest losses in muskmelon. As a secondary messenger, calcium can enhance plant resistance to various stresses. However, it remains unknown whether exogenous calcium affects wound healing and softening in wounded muskmelon fruit. In this study, calcium chloride (CaCl2) and ethylene glycol tetraacetic acid (EGTA) were applied to wounded muskmelon fruit, respectively. After that, all fruit were stored in darkness at 20 ± 1 °C and 85% relative humidity. The results showed that CaCl2 treatment activated phenylpropanoid metabolism related enzymes at the wound sites and promoted the accumulation of phenolic acid monomers and lignin precursors, thereby accelerating the deposition of suberin polyphenolic periderm (SPP) and lignin during wound healing. Meanwhile, CaCl2 treatment suppressed respiration rate and ethylene production, and reduced the content of total soluble solids during storage. By inhibiting the activities of cell wall-degrading enzymes, it further inhibited the degradation of cell wall components such as pectin, cellulose and hemicellulose, consequently delaying fruit softening. In contrast, EGTA treatment inhibited the deposition of SPP and lignin at the wound sites, and promoted wound ethylene production and respiration rate, and accelerated the degradation of cell wall components, thus accelerating fruit softening. In conclusion, exogenous CaCl2 treatment can effectively reduce quality deterioration during storage by accelerating the formation of wound healing structures and delaying softening in wounded muskmelon fruit. These findings offer potential application value for reducing postharvest losses of muskmelon caused by mechanical wound.
Optimizing herbicide efficacy is increasingly critical due to the absence of new herbicide modes of action (MOA) and their widespread overuse. This study developed a satellite-based approach to map herbicide control failures for evaluating efficacy, based on the hypothesis that effective control reduces crop-weeds co-existence and thus spectral-spatial heterogeneity over time, whereas low efficacy increases it. In controlled experimental maize plots (2022–2023), analysis of Unmanned Aerial Vehicle (UAV) multispectral imagery characterized weed-suppression dynamics following application of two herbicides with different MOA. Satellite imagery was processed to select gray-level co-occurrence matrix (GLCM) texture features sensitive to herbicide-induced pixel differences. Features selected were used to compare two satellite-based approaches for mapping herbicide control failures cover (
Silver nanoparticles (AgNPs) were synthesized using Cyamopsis tetragonoloba (C. tetragonoloba) pods (CTP-NPs) powder extract. The following techniques UV–visible spectroscopy, fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the characterization of these synthesized nanoparticles. UV–Visible Spectroscopy confirmed the formation of AgNPs via a distinct Surface Plasmon Resonance (SPR) peak observed at 412 nm, indicating successful reduction. FT-IR Analysis identified key functional groups (e.g., N–H, C = O stretching) responsible for capping and stabilization, with major shifts observed at 3411 cm−1 and 1735.73 cm−1. X-Ray Diffraction (XRD): Revealed a face-centered cubic (FCC) crystalline structure. Scanning Electron Microscopy (SEM): Illustrated a predominantly spherical morphology with average particle size 13 nm. The CTP-AgNPs IC50 values revealed notable variations in DPPH (183.61 μg/mL) in comparison to the ascorbic acid standard (25.7 μg/mL) and hydroxyl radical activity (53.6 μg/mL) in comparison to ascorbic acid (22.47 μg/mL). Antibacterial property of CTP-AgNPs against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) was proved by zone of inhibition 11 ± 0.79 mm and 12 ± 0.78 mm per 100 μg/mL respectively. In vitro anticancer assay demonstrated IC50 value of 18.25 μg/mL against A549 lung cancer cell line, which confirms its potent anticancer potential. Overall, the CTP mediated bio-synthesized AgNPs proved promising in vitro antioxidants by free radical scavenging, antimicrobial by zone of inhibition and anticancer by cytotoxic properties.
The glutamine-binding protein GlnBP is part of an ATP-binding cassette transporter system in Escherichia coli and uses two well-characterized conformational states, an open ligand-free and a closed-liganded state, to facilitate active amino-acid uptake. Existing literature on its ligand-binding mechanism lacked sufficient evidence to univocally assign the kinetic type of binding mechanism for GlnBP: ligand binding prior to conformational change, that is an induced fit, or the conformational selection, in which the ligand binds the matching conformation from a pre-existing ensemble. Since such mechanistic questions are relevant for our fundamental understanding of how this and other biomacromolecules regulate cellular processes, we here revisit the question for GlnBP. We present a biochemical and biophysical analysis using a combination of calorimetry, single-molecule and surface-plasmon resonance spectroscopy, and molecular dynamics simulations. We found that both apo- and holo-GlnBP show no detectable exchange between open and (semi-)closed conformations on timescales between 100 ns and 10 ms and that ligand binding and conformational changes in GlnBP are correlated. A global analysis of our experimental results suggests that the conformational selection model is only compatible with GlnBP for the extreme scenario of very fast conformational exchange between the open and closed states on timescales <100 ns. In contrast, all data remains compatible with an induced-fit mechanism, where the ligand binds GlnBP prior to conformational rearrangements. Importantly, our work demonstrates that it is an intricate task to identify the type of kinetic binding mechanism and that this requires not only a sufficient set of data, but also an integrative experimental and theoretical framework to address the question. Based on this concept, we propose that various protein systems, for which so far only insufficient kinetic data are available, should be revisited.
Cucumber (Cucumis sativus L.), a widely cultivated and important crop, is susceptible to the Tobamovirus cucumber green mottle mosaic virus (CGMMV). CGMMV is known to reduce cucumber yield, yet little is known about its impact on the postharvest quality of the fruit. To examine the effect of CGMMV infection on the quality and storability of cucumber fruit after harvest, cucumber plants were inoculated with CGMMV at three different developmental stages: seedling infection, infection during the vegetative growth of the plants (along with trellis application), and infection during fruit set. Early-stage infections (seedling and trellising) led to significant reductions in yield and impaired fruit quality (shape, color, and weight). Conversely, infections during the fruit set stage produced marketable fruit that showed no apparent differences comparable to non-infected control fruit at harvest. Nevertheless, the quality of fruit after cold storage was significantly affected by CGMMV infection. Virus-infected fruit were more susceptible to chilling injuries, as evidenced by the degradation of fruit peel chlorophyll, increased ion leakage, elevated levels of Malondialdehyde, and higher values of auto-luminescence. Furthermore, CGMMV-infected fruits were more susceptible to gray mold disease caused by Botrytis cinerea. Transcriptomic profiling of infected fruit at harvest revealed upregulation of genes associated with phenylpropanoid and ethylene metabolism, ERF and WRKY transcription factors, suggesting the involvement of several pathways in mediating the differential physiological response of CGMMV-infected fruits to postharvest insults. These results indicate viral infection of fruit as an additional, previously unappreciated factor that affect quality and postharvest losses of fresh produce.
