Copper (Cu) is an essential micronutrient for plants, playing a crucial role in various physiological and molecular processes. Excess Cu induces oxidative stress and disrupts cellular functions, while Cu deficiency causes chlorosis and poor pollen development, thereby reducing crop yields. However, the molecular and evolutionary mechanisms of Cu tolerance and homeostasis remain unclear in the plant kingdom. In this review, we discuss the uptake, transport, and detoxification of Cu through high-affinity Cu transporters (COPTs). Additionally, we update recent studies on maintaining Cu balance by mediating the root exudation of organic acids (e.g., citrate and proline), xylem/phloem loading, cell wall binding, vacuolar sequestration, redistribution, and the activity of antioxidant enzymes (e.g., SOD, CAT, and APX). Furthermore, tissue-specific expression analyses reveal that COPT genes exhibit distinct spatial regulation in the roots and leaves, which are the primary sites of Cu transport and detoxification. Overall, our review highlights the critical roles of COPT gene families and detoxification pathways in maintaining Cu homeostasis in plants. Future research should focus on genetic engineering approaches to enhance Cu tolerance, optimize Cu distribution in grains, and mitigate soil contamination risks. By clarifying these mechanisms, we can develop strategies to sustain crop production under increasing Cu stress, thereby ensuring food security and human health.

Sulfur metabolism plays an important role in plant growth and environmental adaptation. Sulfate transporters (SULTRs) are essential players that mediate sulfur acquisition and distribution in many plants, thereby influencing the cellular redox homeostasis under abiotic stress. In this study, we identified 16 putative HvSULTRs genes in barley at the genome-wide level. The conservation and divergence of the SULTR gene family were assessed through a phylogenetic tree and gene structure analysis, revealing that these genes are closely distributed along the chromosomes. Furthermore, the expression pattern of SULTRs in multiple tissues, including flower, root, leaf, stem, seeds, female, male, root meristem, and apical meristem, were analyzed among ten land plants using a public database. Interestingly, the expression of HvSULTR2, HvSULTR4, and HvSULTR5 was upregulated after four days of heat treatment, suggesting their importance in barley’s adaptive response to heat stress. In addition, HvSULTR11 was confirmed to be localized at the plasma membrane and display functional interactions with Hv14-3-3A/Hv14-3-3D. In addition, haplotypes of the HvSULTR11 based on SNP (Single Nucleotide Polymorphism) were divided into ten types across 123 barley varieties. Together, these results provide a new clue to clarify the molecular mechanism of SULTRs in stress response and a new candidate gene resource to enhance the stress (e.g., heat and drought) tolerance in barley.

Heavy metals in the soil inhibit plant growth, which significantly reduce the crop yield and quality. Natural Resistance-Associated Macrophage Proteins (NRAMP) are widely distributed on the plasma and vacuolar membranes of plant roots, stems, and leaves. The NRAMP gene family plays a crucial role in modulating plant heavy-metal uptake, sequestration, distribution, and translocation, while the molecular evolution and mechanisms underlying these processes remain unclear. Here, we reviewed recent progress on plant NRAMP genes, focusing on their structural characteristics and functions in the absorption, transport, accumulation, and detoxification of various heavy metals. Furthermore, we performed an evolutionary analysis of NRAMP in green plants, indicating expansion and tandem duplication in ferns. In addition, their key amino acid sequences and secondary structures were highly conserved across plant species. The expression of diverse tissue showed that NRAMP genes displayed distinct spatial regulation in the leaves and roots. We also explored the underlying molecular mechanisms and regulatory pathways by which NRAMP genes influence heavy metal uptake. Therefore, by integrating structural conservation, molecular evolution, tissue- and single-cell expression patterns, ion-stress-responsive expression, regulatory pathways, and the Cd–Mn nutrient–toxin trade-off, this review provides a framework for identifying unresolved NRAMP functions and for guiding future strategies in low-heavy-metal crop breeding, metal homeostasis engineering, and phytoremediation.

Saline irrigation is a major constraint to crop production in newly reclaimed desert lands, even when pre-sowing soil salinity is low. This two-season field study evaluated whether plant growth-promoting rhizobacteria could improve barley performance under saline irrigation water with an electrical conductivity of 11.8 dS m⁻¹ in the El Moghra region, Egypt. The barley cultivar Giza 2000 was grown under five inoculation treatments: an uninoculated saline-irrigated control; a single inoculation with Azospirillum lipoferum; and combined inoculations with A. lipoferum and Bacillus coagulans, Bacillus circulans, or Enterobacter cloacae. Because freshwater was unavailable at the experimental site, treatment effects were evaluated relative to the saline-irrigated control. Across both growing seasons, single inoculation with A. lipoferum produced the most consistent improvements in growth, yield formation, nutrient accumulation, soil biological activity, and seed nutritional quality. The combined treatment of A. lipoferum and B. circulans was generally the second-most effective. Bacterial inoculation also improved adjustment to physiological stress, as indicated by greater proline accumulation, lower antioxidant enzyme activities, and enhanced expression of stress-related genes associated with proline biosynthesis and secondary metabolism. Overall, the results indicate that A. lipoferum applied alone was more effective than the tested combinations of bacteria under saline irrigation. These findings provide field-based evidence that inoculant performance depends on strain composition and that single-strain inoculation can be a promising strategy for improving barley production in reclaimed sandy soils irrigated with saline water.