In this work, a novel molecularly imprinted polymer (MIP) with water-soluble CdTe quantum dots (QDs) was synthesized by oil-in-water Pickering emulsion polymerization using whole Listeria monocytogenes as the template. Listeria monocytogenes was first treated by acryloyl-functionalized chitosan with QDs to form a bacteria–chitosan network as the water phase. This was then stabilized in an oil-in-water emulsion comprising a cross-linker, monomer, and initiator, causing recognition sites on the surface of microspheres embedded with CdTe QDs. The resulting MIP microspheres enabled selective capture of the target bacteria via recognition cavities. The target bacteria Listeria monocytogenes was detected. Scanning electron microscopy (SEM) characterization showed that the MIPs had a rough spherical shape. There was visual fluorescence detection via quenching in the presence of the target molecule, which offered qualitative detection of Listeria monocytogenes in milk and pork samples. The developed method simplified the analysis process and did not require any sample pretreatment. In addition, the fluorescence sensor provided an effective, fast, and convenient method for Listeria monocytogenes detection in food samples.

Almost all living organisms require manganese (Mn) as an essential trace element for survival. To maintain an irreplaceable role in the oxygen-evolving complex of photosynthesis, plants require efficient Mn uptake in roots and delivery to above-ground tissues. However, the underlying mechanisms of root-to-shoot Mn translocation remain unclear. Here, we identified an Natural Resistance Associated Macrophage Protein (NRAMP) family member in maize (Zea mays), ZmNRAMP2, which localized to the tonoplast in maize protoplasts and mediated transport of Mn in yeast (Saccharomyces cerevisiae). Under Mn deficiency, two maize mutants defective in ZmNRAMP2 exhibited remarkable reduction of root-to-shoot Mn translocation along with lower shoot Mn contents, resulting in substantial decreases in F_v/F_m and plant growth inhibition compared to their corresponding wild-type (WT) plants. ZmNRAMP2 transcripts were highly expressed in xylem parenchyma cells of the root stele. Compared to the WT, the zmnramp2-1 mutant displayed lower Mn concentration in xylem sap accompanied with retention of Mn in root stele. Furthermore, the overexpression of ZmNRAMP2 in transgenic maize showed enhanced root-to-shoot translocation of Mn and improved tolerance to Mn deficiency. Taken together, our study reveals a crucial role of ZmNRAMP2 in root-to-shoot translocation of Mn via accelerating vacuolar Mn release in xylem parenchyma cells for adaption of maize plants to low Mn stress and provides a promising transgenic approach to develop low Mn-tolerant crop cultivars.

Saline–alkali stress is one of the major factors limiting oat seed germination. The regulatory role of melatonin (MT) as a naturally occurring active substance is well known, but the mechanism of MT-mediated intrinsic physiological regulation of oat seed germination under saline–alkali stress is unclear. Therefore, this study investigated (1) the variability of different MT seed soaking concentrations and times on the germination of oat seeds under saline–alkali stress, and (2) the possible physiological regulatory mechanisms of MT on the germination of oat seeds under saline–alkali stress. The results showed that seed vigor was significantly reduced under saline–alkali stress, and seed germination of oats was significantly inhibited; different concentrations of MT seed soaking treatments improved the germination rate, germination potential, germination index, vigor index, root length, germ length, fresh weight, and dry weight; and, overall, treatment improved seed germination and exhibited the phenomenon of “low promotion and high inhibition”. The 100 μmol·L⁻¹ MT seed soaking treatment effectively enhanced the activities of seed antioxidant enzymes (SOD, POD, CAT, and APX) and nonenzymatic antioxidants (GSH and AsA), affected the AsA-GSH cycle, and effectively increased the contents of osmoregulatory substances (proline, protein, and soluble sugar) by reducing levels of H₂O₂, OH⁻, and MDA, thus enhancing the tolerance of oats to saline–alkali and promoting seed germination. In conclusion, MT has a positive effect on the saline–alkali tolerance of oat seeds.

To cope with the yield loss caused by drought stress, new oat varieties with greater drought tolerance need to be selected. In this study, two oat varieties with different drought tolerances were selected for analysis of their phenotypes and physiological indices under moderate and severe soil drought stress. The results revealed significant differences in the degree of wilting, leaf relative water content (RWC), and SOD and CAT activity between the two oat genotypes under severe soil drought stress; moreover, the drought-tolerant variety exhibited a significant increase in the number of stomata and wax crystals on the surface of both the leaf and guard cells; additionally, the morphology of the guard cells was normal, and there was no significant disruption of the grana lamella membrane or the nuclear envelope. Furthermore, transcriptome analysis revealed that the expression of genes related to the biosynthesis of waxes and cell-wall components, as well as those of the WRKY family, significantly increased in the drought-tolerant variety. These findings suggest that several genes involved in the antioxidant pathway could improve drought tolerance in plants by regulating the increase/decrease in wax and cell-wall constituents and maintaining normal cellular water potential, as well as improving the ability of the antioxidant system to scavenge peroxides in oats.