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Chromium (Cr) is a toxic heavy element that interferes with plant metabolite biosynthesis and modifies the plant rhizosphere microenvironment, affecting plant growth. However, the interactions and response mechanisms between plants and rhizosphere bacteria under Cr stress still need to be fully understood. In this study, we used Iris tectorum as a research target and combined physiology, metabolomics, and microbiology to reveal the stress response mechanism of I. tectorum under heavy metal chromium stress. The results showed that Cr stress-induced oxidative stress inhibited plant growth and development and increased malondialdehyde and oxygen free radicals content. Also, it increased ascorbate peroxidase, peroxidase activity, and superoxide dismutase activity, as well as glutathione and soluble sugar content. Microbiome analysis showed that Cr stress changed the rhizosphere bacterial community diversity index by 33.56%. Proteobacteria, Actinobacteriota, and Chloroflexi together accounting for 71.21% of the total sequences. Meanwhile, the abundance of rhizosphere dominant and plant-promoting bacteria increased significantly with increasing time of Cr stress. The improvement of the soil microenvironment and the recruitment of bacteria by I. tectorum root secretions were significantly enhanced. By metabolomic analysis, five vital metabolic pathways were identified, involving 89 differentially expressed metabolites, divided into 15 major categories. In summary, a multi-omics approach was used in this study to reveal the interaction and stress response mechanisms between I. tectorum and rhizosphere bacterial communities under Cr stress, which provided theoretical basis for plant-microbial bioremediation of Cr-contaminated soils in constructed wetlands. This may provide more valuable information for wetland remediation of heavy metal pollution.

Heat stress is an increasingly concerning topic under global warming. Heat stress can induce organisms to produce excess reactive oxygen species, which will lead to cell damage and destroy the antioxidant defense of aquatic animals. Chinese mitten crab, Eriocheir sinensis, is sensitive to the change in water temperature, and parent crabs are more vulnerable during the breeding stage. In the present study, the multi-omics responses of parent E. sinensis gills to heat stress (24 h) were determined via transcriptome and proteome. The integrative analysis revealed that heat shock protein 70 (HSP70) and glutathione s-transferase (GST) were significantly up-regulated at gene and protein levels after heat stress, indicating that HSP70 and the antioxidant system participated in the regulatory mechanism of heat stress to resist oxidative damage. Moreover, the “Relaxin signaling pathway” was also activated at gene and protein levels under 30 °C stress, which implied that relaxin may be essential and responsible for reducing the oxidative damage of gills caused by extreme heat stress. These findings provided an understanding of the regulation mechanism in E. sinensis under heat stress at gene and protein levels. The mining of key functional genes, proteins, and pathways can also provide a basis for the cultivation of new varieties resistant to oxidative stress.

Recent pharmacological studies have shown that dragon’s blood has an anti-cerebral ischemia effect. Loureirin C (LC), a kind of dihydrochalcone compound in dragon’s blood, is believed to be play an important role in the treatment of ischemia stroke, but fewer studies for LC have been done. In this paper, we report the first experimental and theoretical studies on the antioxidation mechanism of LC by radical scavenging. The experimental studies show that LC has almost no effect on cell viability under 15 μM for the SH-SY5Y cells without any treatments. For the SH-SY5Y cells with oxygen and glucose deprivation-reperfusion (OGD/R) treatment, LC increased the viability of SH-SY5Y cells. The results of 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) and MitoSox Red experiments indicate that LC is very efficient in inhibiting the generation of the intracellular/mitochondrial reactive oxygen species (ROS) or removing these two kinds of generated ROS. The density functional theory (DFT) calculations allowed us to elucidate the antioxidation mechanisms of LC. Fukui function analysis reveals the radical scavenging of LC by hydrogen abstraction mechanism, the complex formation by e-transfer, and radical adduct formation (RAF) mechanism. Among the H-abstraction, the complex formation by e-transfer, and radical adduct formation (RAF) reactions on LC, the H-abstraction at O-H35 position by OH• is favorable with the smallest energy difference between the product and two reactants of the attack of OH• to LC of −0.0748 Ha. The bond dissociation enthalpies (BDE), proton affinities (PA), ionization potential (IP), proton dissociation enthalpy (PDE), and electron transfer enthalpy (ETE) were calculated to determine thermodynamically preferred reaction pathway for hydrogen abstraction mechanism. In water, IP and the lowest PDE value at O3-H35 position are lower than the lowest BDE value at O3-H35 position; 41.8986 and 34.221 kcal/mol, respectively, indicating that SEPT mechanism is a preferred one in water in comparison with the HAT mechanism. The PA value of O3-H35 of LC in water is −17.8594 kcal/mol, thus the first step of SPLET would occur spontaneously. The minimum value of ETE is higher than the minimum value of PDE at O3-H35 position and IP value, 14.7332 and 22.4108 kcal/mol, respectively, which suggests that the SEPT mechanism is a preferred one in water in comparison with the SPLET mechanism. Thus, we can draw a conclusion that the SEPT mechanism of is the most favorite hydrogen abstraction mechanism in water, and O-H35 hydroxyl group has the greatest ability to donate H-atoms.

Low temperature is a major adverse environmental factor that impairs petunia growth and development. To better understand the molecular mechanisms of cold stress adaptation of petunia plants, a quantitative proteomic analysis using iTRAQ technology was performed to detect the effects of cold stress on protein expression profiles in petunia seedlings which had been subjected to 2°C for 5d. Of the 2,430 proteins whose levels were quantitated, a total of 117 proteins were discovered to be differentially expressed under low temperature stress in comparison to unstressed controls. As an initial study, 44 proteins including well known and novel cold-responsive proteins were successfully annotated. By integrating the results of two independent Gene Ontology (GO) enrichment analyses, seven common GO terms were found of which oxidation-reduction process was the most notable for the cold-responsive proteins. By using the subcellular localization tool Plant-mPLoc predictor, as much as 40.2% of the cold-responsive protein group was found to be located within chloroplasts, suggesting that the chloroplast proteome is particularly affected by cold stress. Gene expression analyses of 11 cold-responsive proteins by real time PCR demonstrated that the mRNA levels were not strongly correlated with the respective protein levels. Further activity assay of anti-oxidative enzymes showed different alterations in cold treated petunia seedlings. Our investigation has highlighted the role of antioxidation mechanisms and also epigenetic factors in the regulation of cold stress responses. Our work has provided novel insights into the plant response to cold stress and should facilitate further studies regarding the molecular mechanisms which determine how plant cells cope with environmental perturbation.