Cadmium (Cd) contamination in soil threatens global food production and human health. This study investigated zinc (Zn) addition as a potential strategy to mitigate Cd stress using two barley genotypes, Dong-17 (Cd-sensitive) and WSBZ (Cd-tolerant). Hydroponically grown seedlings were treated with different Cd (0, 1.0, 10 mu M) and Zn (0, 5, 50 mu M) levels. Results showed that Zn addition effectively alleviated Cd induced growth inhibition, improving SPAD values, photosynthetic parameters, fluorescence efficiency (Fv/Fm), and biomass. Zn reduced Cd contents in roots and shoots, inhibited Cd translocation, and ameliorated Cd induced ultrastructural damage to organelles. Transcriptomic analysis revealed distinct gene expression patterns between genotypes, with WSBZ showing enhanced expression of metal transporters, antioxidant defense, and stress signaling genes. Significantly, cell wall related pathways were upregulated in WSBZ, particularly lignin biosynthesis genes (PAL, C4H, 4CL, COMT, CAD/SAD), suggesting cell wall reinforcement as a key Cd tolerance mechanism. Zn induced upregulation of ZIP family transporters and downregulation of Cd transporters (HvHMA) aligned with reduced Cd accumulation. These findings provide comprehensive insights into molecular mechanisms of Zn mediated alleviation of Cd toxicity in barley, supporting improved agronomic practices for Cd contaminated soils.

Iron homeostasis is critical for plant growth; however, the mechanisms underlying responses to iron deficiency and toxicity remain poorly understood. We investigated the adaptive strategies of Ulmus pumila, focusing on leaf physiological, transcriptomic, and metabolomic responses to iron stresses. Both iron deficiency and toxicity impaired chlorophyll biosynthesis, PS II efficiency, and chloroplast ultrastructure, resulting in reduced photosynthetic capacity and etiolation/wilting phenotypes. Iron deficiency reduced antioxidant enzyme activity and ROS levels, while iron toxicity activated the antioxidant enzyme system in response to the ROS burst. Integrated transcriptomic and metabolomic analyses provided insights into the underlying mechanism of these divergent responses: iron deficiency promoted primary metabolic adjustments, particularly the upregulation of genes (e.g., MDH, ACO, and IDH) and metabolites (e.g., malic acid, citric acid, and fumaric acid) associated with the TCA cycle to meet energy demands. Conversely, iron toxicity triggered a metabolic shift from primary to secondary metabolism, upregulating the genes (e.g., CHS, CHI, and F3H) and metabolites (e.g., laricitrin, trifolin, and rutin) involved in flavonoids biosynthesis to mitigate oxidative stress. Overall, U. pumila employs distinct adaptive mechanisms to balance survival and growth under iron stress: prioritizing energy metabolism and iron uptake to meet energy demands and improve iron uptake efficiency under deficiency, and enhancing the secondary metabolism to mitigate oxidative damage under toxicity. These findings enhance understanding of plant nutrient homeostasis and stress adaptation, providing insights into mitigating the impacts of soil degradation on agriculture and forestry.

Phytophthora capsici is an infamously soil-borne pathogen that poses a serious threat to agricultural production. Curcumol is a natural plant-derived sesquiterpene lactone, whose antimicrobial effect against plant pathogens remains unclear. In this study, curcumol exhibited pronounced antifungal activity against a diverse range of plant pathogens, particularly against plant pathogenic oomycetes, which including P. capsici, Phytophthora infestans, Phytophthora parasitica, and Phytophthora sojae. The median effective concentration values of curcumol against P. capsici for spore germination and mycelial growth were 4.75 and 2.11 mu g mL- 1, respectively. After treatment with curcumol, mycelia of P. capsici exhibited morphological and ultrastructual defects, which included swelling, hyperbranching, dissolution of plasma membrane, and loss of organelles. In addition, curcumol effectively inhibited the synthesis of phosphatidylcholine (PC), a primary component of cell membrane, by downregulating the expression levels of genes participated in PC synthesis such as Phospholipid N-methyltransferase and Cholinephosphotransferase. This inhibition decreased the accumulation of PC and phospholipids within the cell, thereby increasing the cell membrane permeability and damaging its integrity. In the in vivo antifungal tests, curcumol reduced the disease incidence of P. capsici on tomato leaves as well as pepper seedlings. The systemicity tests further validated the strong phloem and xylem mobility of curcumol in both upward and downward directions. Taken together, these results indicated that curcumol could effectively combat diseases caused by P. capsici and had the potential for development into a novel fungicide for P. capsici management.

Climate change not only leads to high temperatures, droughts, floods, storms and declining soil quality, but it also affects the spread and mutation of pests and diseases, which directly influences plant growth and constitutes a new challenge to food security. Numerous hormones like auxin, ethylene and melatonin, regulate plant growth and development as well as their resistance to environmental stresses. To mitigate the impact of diverse biotic and abiotic stressors on crops, single or multiple phytohormones in combination have been applied. Melatonin is a multifunctional signaling molecule engaged in the development and stress response of plants. In the current review, we discuss the synthesis and action of melatonin, as well as its utilization for plant resistance to different stresses from the perspective of practical application. Simultaneously, we elucidate the regulatory effects and complex mechanisms of melatonin and other plant hormones on the growth of plants, explore the practical applications of melatonin in combination with other phytohormones in crops. This will aid in the planning of management strategies to protect plants from damage caused by environmental stress.

In recent years, alkaline soda soil has stimulated numerous biological research on plants under carbonate stress. Here, we explored the difference in physiological regulation of rice seedlings between saline (NaCl) and alkaline carbonate (NaHCO3 and Na2CO3) stress. The rice seedlings were treated with 40 mM NaCl, 40 mM NaHCO3 and 20 mM Na2CO3 for 2 h, 12 h, 24 h and 36 h, their physiological characteristics were determined, and organic acid biosynthesis and metabolism and hormone signalling were identified by transcriptome analysis. The results showed that alkaline stress caused greater damage to their photosynthetic and antioxidant systems and led to greater accumulation of organic acid, membrane damage, proline and soluble sugar but a decreased jasmonic acid content compared with NaCl stress. Jasmonate ZIM-Domain (JAZ), the probable indole-3-acetic acid-amido synthetase GH3s, and the protein phosphatase type 2Cs that related to the hormone signalling pathway especially changed under Na2CO3 stress. Further, the organic acid biosynthesis and metabolism process in rice seedlings were modified by both Na2CO3 and NaHCO3 stresses through the glycolate/glyoxylate and pyruvate metabolism pathways. Collectively, this study provides valuable evidence on carbonate-responsive genes and insights into the different molecular mechanisms of saline and alkaline stresses.

Streptomyces from unexplored or underexplored environments may be an essential source of discoveries of bioactive molecules. One such example is Streptomyces qaidamensis S10(T), which was isolated from a sand sample collected in Qaidam Basin, Qinghai Province, China. Here, we report on (+/-)-differolide, an antioxidant isolated from S. qaidamensis, and verified with scavenging experiments on 2,2-diphenyl-1-picrylhydrazyl (DPPH). The biosynthetic gene cluster responsible for synthesizing the compound was also identified using comparative genomic methods. These results provide a basis for further study of the biological activities of (+/-)-differolide, which also make it possible to develop as an antioxidant medicine.

Main observation and conclusion The aminoglycoside antibiotic apramycin contains a unique bicyclic octose moiety, and biosynthesis of this moiety involves an oxidoreductase AprQ. Unlike other known Q series proteins involved in aminoglycosides biosynthesis, AprQ does not work with an aminotransferase partner, and performs a four-electron oxidation that converts a CH2OH moiety to a carboxylate group. In this study, we report mechanistic investigation of AprQ. We showed AprQ contains a flavin mononucleotide (FMN) cofactor, which is different from other known Q series enzymes that contain a flavin adenine dinucleotide (FAD) cofactor. A series of biochemical assays showed that AprQ is not a monooxygenase but a flavoprotein oxidase. Although molecular O-2 is strictly required for reaction turnover, four-electron oxidation can be achieved in the absence of O-2 in single turnover condition. These findings establish the detailed catalytic mechanism of AprQ and expand the growing family of flavoprotein oxidases, an increasingly important class of biocatalysts.