Physiological and molecular mechanisms of ZnO quantum dots mitigating cadmium stress in Salvia miltiorrhiza.

This study delved into the physiological and molecular mechanisms underlying the mitigation of cadmium (Cd) stress in the model medicinal plant Salvia miltiorrhiza through the application of ZnO quantum dots (ZnO QDs, 3.84 nm). A pot experiment was conducted, wherein S. miltiorrhiza was subjected to Cd stress for six weeks with foliar application of 100 mg/L ZnO QDs. Physiological analyses demonstrated that compared to Cd stress alone, ZnO QDs improved biomass, reduced Cd accumulation, increased the content of photosynthetic pigments (chlorophyll and carotenoids), and enhanced the levels of essential nutrient elements (Ca, Mn, and Cu) under Cd stress. Furthermore, ZnO QDs significantly lowered Cd-induced reactive oxygen species (ROS) content, including H2O2, O2-, and MDA, while enhancing the activity of antioxidant enzymes (SOD, POD, APX, and GSH-PX). Additionally, ZnO QDs promoted the biosynthesis of primary and secondary metabolites, such as total protein, soluble sugars, terpenoids, and phenols, thereby mitigating Cd stress in S. miltiorrhiza. At the molecular level, ZnO QDs were found to activate the expression of stress signal transduction-related genes, subsequently regulating the expression of downstream target genes associated with metal transport, cell wall synthesis, and secondary metabolite synthesis via transcription factors. This activation mechanism contributed to enhancing Cd tolerance in S. miltiorrhiza. In summary, these findings shed light on the mechanisms underlying the mitigation of Cd stress by ZnO QDs, offering a potential nanomaterial-based strategy for enhancing Cd tolerance in medicinal plants.

Unraveling the molecular freezing behavior of water on a calcium silicate hydrate matrix.

The hydration process of cement-based materials primarily results in the formation of calcium silicate hydrate (CSH), which is crucial in deciding how long concrete will last. This study utilizes molecular dynamics simulation technology to explore the freezing behavior of pure water solutions within various calcium silicate hydrate (CSH) matrices. The investigated matrices encompass four different Ca/Si ratios. According to the simulation, as ice crystals develop close to the surface of CSH, the CSH matrix strengthens its hydrogen and ionic interactions with water molecules, which effectively prevents water molecules from crystallizing and nucleating. Consequently, these molecules compose an unfrozen water film structure that bridges between ice crystals and the CSH matrix. The research also reveals an intriguing relationship between silica chain behavior on the Ca/Si ratio and the CSH surface. Surface flaws arise as a result of the silica chains of CSH breaking into shorter segments as the Ca/Si ratio increases. These surface defects manifest as grooves on the matrix's surface, effectively capturing and retaining specific water molecules. The CSH matrix's hydrogen bonds with water molecules are weakened as a result of this process, facilitating their participation in the crystallization process, and leading to a thinner unfrozen water film thickness with an increased Ca/Si ratio. This study contributes to a greater knowledge of the performance and dependability of cement-based products by offering molecular-level insights into the freezing actions of liquids in gel pores.

ZnO quantum dots alleviate salt stress in Salvia miltiorrhiza by enhancing growth, scavenging reactive oxygen species, and modulating stress-responsive genes.

Experiments were conducted to investigate the alleviating effects of ZnO quantum dots (ZnO QDs) on salt stress in Salvia miltiorrhiza by comparing them with conventional ZnO nanoparticles (ZnO NPs). The results demonstrated that compared with salt stress alone, foliar application of ZnO QDs significantly improved the biomass as well as the total chlorophyll and carotenoids contents under salt stress. ZnO QDs reduced H2O2 and MDA levels, decreased non-enzymatic antioxidant (ASA and GSH) content, and improved antioxidant enzyme (POD, SOD, CAT, PAL, and PPO) activity under salt stress. Metal elemental analysis further demonstrated that the ZnO QDs markedly increased Zn and K contents while decreasing Na content, resulting in a lower Na/K ratio compared to salt stress alone. Finally, RNA sequencing results indicated that ZnO QDs primarily regulated genes associated with stress-responsive pathways, including plant hormone signal transduction, the MAPK signaling pathway, and metabolic-related pathways, thereby alleviating the adverse effects of salt stress. In comparison, ZnO NPs did not exhibit similar effects in terms of improving plant growth, enhancing the antioxidant system, or regulating stress-responsive genes under salt stress. These findings highlight the distinct advantages of ZnO QDs and suggest their potential as a valuable tool for mitigating salt stress in plants.

Identification and characterization of a novel tyrosine aminotransferase gene (SmTAT3-2) promotes the biosynthesis of phenolic acids in Salvia miltiorrhiza Bunge.

Rosmarinic acid (RA) and salvianolic acid B (SAB) are main phenolic acids in Salvia miltiorrhiza Bunge have been widely used in the treatment of cardiovascular and cerebrovascular diseases due to their excellent pharmacological activity. RA is a precursor of SAB, and tyrosine transaminase (TAT, EC 2.6.1.5) is a crucial rate-limiting enzyme in their metabolism pathway. This study identified a novel TAT gene, SmTAT3-2, and found that it is a new transcript derived from unconventional splicing of SmTAT3. We used different substrates for enzymatic reaction with SmTAT1, SmTAT3 and SmTAT3-2. Subcellular localization of SmTAT1 and SmTAT3-2 was completed based on submicroscopic techniques. In addition, they were overexpressed and CRISPR/Cas9 gene edited in hairy roots of S. miltiorrhiza. Revealed SmTAT3-2 and SmTAT1 showed a stronger affinity for L-tyrosine than SmTAT3, localized in the cytoplasm, and promoted the synthesis of phenolic acid. In overexpressed SmTAT3-2 hairy roots, the content of RA and SAB was significantly increased by 2.53 and 3.38 fold, respectively, which was significantly higher than that of overexpressed SmTAT1 strain compared with EV strain. These findings provide a valuable key enzyme gene for the phenolic acids metabolism pathway and offer a theoretical basis for the clinical application.

Molecular insights into the interfacial adhesion mechanism between carbon nanotubes and epoxy resin.

In recent years, carbon nanotubes (CNTs) have garnered widespread attention and have been deemed the preferred option for the creation of epoxy composites, owing to their outstanding mechanical properties. Despite this, the interaction between pure CNTs and epoxy resin is primarily dependent on van der Waals forces and therefore, the interfacial forces are weak, making it challenging for effective load transfer. To enhance the mechanical properties of the composites, surface functionalization is often deemed a more favorable method for improving interfacial bond strength. This study employs molecular dynamics simulations to examine the interfacial bonding characteristics between functionalized CNTs and epoxy resin. The results demonstrate that functional group modification can significantly improve the interfacial adhesion between CNTs and epoxy resin, and the incorporation of functional groups can enhance the crosslinking degree of the epoxy resin at the interface. The hydrogen bond network established between the CNTs and epoxy resin after functional group modification, and the high stability of the bond cooperation, are factors contributing to the excellent interfacial performance.

Genome-Wide Analysis of the MADS-box Gene Family and Expression Analysis during Anther Development in Salvia miltiorrhiza.

MADS-box genes constitute a large family of transcription factors that play important roles in plant growth and development. However, our understanding of MADS-box genes involved in anther development and male sterility in Salvia miltiorrhiza is still limited. In this study, 63 MADS-box genes were identified from the genome of the male sterility ecotype Sichuan S. miltiorrhiza (S. miltiorrhiza_SC) unevenly distributed among eight chromosomes. Phylogenetic analysis classified them into two types and 17 subfamilies. They contained 1 to 12 exons and 10 conserved motifs. Evolution analysis showed that segmental duplication was the main force for the expansion of the SmMADS gene family, and duplication gene pairs were under purifying selection. Cis-acting elements analysis demonstrated that the promoter of SmMADS genes contain numerous elements associated with plant growth and development, plant hormones, and stress response. RNA-seq showed that the expression levels of B-class and C-class SmMADS genes were highly expressed during anther development, with SmMADS11 likely playing an important role in regulating anther development and male fertility in S. miltiorrhiza_SC. Overall, this study provides a comprehensive analysis of the MADS-box gene family in S. miltiorrhiza, shedding light on their potential role in anther development and male sterility.

Integrated Multiomics and Synergistic Functional Network Revealed the Mechanism in the Tolerance of Different Ecotypes of Salvia miltiorrhiza Bge. to Doxycycline Pollution.

Tetracycline pollution in soil irreversibly damages the biosafety of plants by inhibiting the mitochondrial function. Some traditional Chinese medicine (TCM) plants, such as Salvia miltiorrhiza Bunge, have a strong tolerance to mitochondrial damage. We comprehensively compared the doxycycline (DOX) tolerances of two ecotypes of S. miltiorrhiza in the Sichuan and Shandong provinces and found that the Sichuan ecotype had a lower yield reduction, more stable accumulation of medicinal ingredients, higher mitochondrial integrity, and a more robust antioxidant system. The synergetic response networks under DOX pollution of both ecotypes were constructed using RNA sequencing and ultrahigh-performance liquid chromatography-tandem mass spectrometry. The differentiation of the downstream pathways of aromatic amino acids (AAAs) produced variations in the DOX tolerance of S. miltiorrhiza in different regions. The Sichuan ecotype maintained redox homeostasis and xylem development by activating salvianolic acid and indole biosynthesis, while the Shandong ecotype balanced chemical and mechanical defenses by regulating the flavonoid biosynthesis. Rosmarinic acid, a downstream AAA molecule, maintains the mitochondrial homeostasis of plant seedlings under DOX pollution by targeting the ABCG28 transporter. We also highlight the significance of downstream AAA small molecules in guiding the development of bio-based environmental pollution remediation agents.

TpIRT1 from Polish wheat (Triticum polonicum L.) enhances the accumulation of Fe, Mn, Co, and Cd in Arabidopsis.

Uptake and internal transport of micronutrients are essential for plant growth, development, and yield. In this regard, Iron Regulated Transporters (IRTs) from the Zinc Regulated Transporter (ZRT)/IRT-related protein (ZIP) family play an important role in transition metal uptake. Most studies have been focused on IRT1-like proteins in diploid species. Information on IRT1-like proteins in polyploids is limited. Here, we studied the function of TpIRT1A and TpIRT1B homoeologs in a tetraploid crop, Polish wheat (Triticum polonicum L.). Our results highlighted the importance of TpIRT1 in mediating the uptake and translocation of Fe, Mn, Co, and Cd with direct implications for wheat yield potential. Both TpIRT1A and TpIRT1B were located at the plasma membrane and internal vesicle-like organelle in protoplasts of Arabidopsis thaliana L. and increased Cd and Co sensitivity in yeast. The over-expression of TpIRT1B in A. thaliana increased Fe, Mn, Co, and Cd concentration in its tissues and improved plant growth under Fe, Mn, and Co deficiencies, while increased the sensitivity to Cd compared to wild type. Functional analysis of IRT1 homoeologs from tetraploid and diploid ancestral wheat species in yeast disclosed four distinct amino acid residues in TdiIRT1B (T. dicoccum L. (Schrank)) and TtuIRT1B (T. turgidum L.). Together, our results increase the knowledge of IRT1 function in a globally important crop, wheat.

The semi-dwarfing gene Rht-dp from dwarf polish wheat (Triticum polonicum L.) is the "Green Revolution" gene Rht-B1b.

BACKGROUND: The wheat dwarfing gene increases lodging resistance, the grain number per spike and harvest index. Dwarf Polish wheat (Triticum polonicum L., 2n = 4x = 28, AABB, DPW), initially collected from Tulufan, Xinjiang, China, carries a semi-dwarfing gene Rht-dp on chromosome 4BS. However, Rht-dp and its dwarfing mechanism are unknown. RESULTS: Homologous cloning and mapping revealed that Rht-dp is the 'Green Revolution' gene Rht-B1b. A haplotype analysis in 59 tetraploid wheat accessions showed that Rht-B1b was only present in T. polonicum. Transcriptomic analysis of two pairs of near-isogenic lines (NILs) of DPW × Tall Polish wheat (Triticum polonicum L., 2n = 4x = 28, AABB, TPW) revealed 41 differentially expressed genes (DEGs) as potential dwarfism-related genes. Among them, 28 functionally annotated DEGs were classed into five sub-groups: hormone-related signalling transduction genes, transcription factor genes, cell wall structure-related genes, reactive oxygen-related genes, and nitrogen regulation-related genes. CONCLUSIONS: These results indicated that Rht-dp is Rht-B1b, which regulates pathways related to hormones, reactive oxygen species, and nitrogen assimilation to modify the cell wall structure, and then limits cell wall loosening and inhibits cell elongation, thereby causing dwarfism in DPW.

Different nitrogen forms differentially affect Cd uptake and accumulation in dwarf Polish wheat (Triticum polonicum L.) seedlings.

This study investigated the effects of different nitrogen (N) forms on Cadmium (Cd) uptake and accumulation in dwarf Polish wheat (DPW) seedlings, which were grown under Cd stress with N-Null, NH4+-N, NO3--N and NH4+-N + NO3--N. We measured plant growth and determined Cd uptake, translocation, accumulation, subcellular distribution and chemical forms in the roots and shoots of DPW seedlings. We also analyzed saccharide concentrations, and the transcript levels of genes encoding metal transporters in the roots of DPW seedlings. In the absence of NO3--N, addition of NH4+-N reduced roots Cd concentration, FCW (Cd in cell wall), FS (Cd in soluble fraction) and FE (inorganic Cd) concentrations, and induced the expression of four genes encoding metal transporters in roots, while it promoted Cd translocation to shoots. In the presence of NO3--N, addition of NH4+-N increased roots Cd concentration, FCW and FW concentrations, and induced the expression of 22 genes encoding metal transporters in roots. Regardless of NH4+-N level, addition of NO3--N increased roots Cd concentration, FCW, FS, FW (water-soluble Cd), FNaCl (pectates and protein Cd), FHAc (undissolved Cd phosphate) and lactose concentrations, and also induced the expression of genes encoding metal transporters in roots. Overall, NH4+-N differently regulated Cd uptake and accumulation in DPW seedlings in the absence or presence of NO3--N, while NO3--N greatly increased Cd uptake and accumulation in the presence of NH4+-N compared to the absence of NH4+-N. These patterns of Cd alteration likely arose due to different N forms altering Cd subcellular distribution and chemical forms, lactose concentration and the expression of metal transporter genes.

Ammonium N influences the uptakes, translocations, subcellular distributions and chemical forms of Cd and Zn to mediate the Cd/Zn interactions in dwarf polish wheat (Triticum polonicum L.) seedlings.

Ammonium (NH4+) would influence the uptake and translocation of Cd and Zn to mediate their interactions in wheat. Thus, the effects of NH4+ on Cd and Zn uptake, translocation, subcellular distributions and Cd chemical forms in dwarf polish wheat (DPW, Triticum polonicum L.) under Cd, Zn and Cd + Zn stresses with lack or supply of NH4+ was investigated. The biomasses of root and shoot were reduced by NH4+. NH4+ enhanced Cd and Zn uptakes, but inhibited their translocations. Under lack and supply of NH4+, Zn inhibited Cd uptakes, but promoted Cd translocations. Meanwhile, NH4+ reinforced the inhibition of Cd uptake and the promotion of Cd translocation caused by Zn. Cd inhibited Zn uptake and promoted Zn translocation under lack of NH4+. Meanwhile, Cd slightly reduced the Zn uptake, but did not affect the translocation under supply of NH4+. Therefore, NH4+ alleviated the inhibition of Zn uptake and partly reduced the promotion of Zn translocation stimulated by Cd. NH4+ and Zn changed the subcellular distributions and chemical forms of Cd. NH4+ and Cd also influenced the subcellular distributions of Zn. The changed subcellular distributions and chemical forms were associated with Cd and Zn uptakes and translocations, which physiologically revealed and illustrated NH4+ participates in Cd/Zn interactions.