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To enable the use of anthocyanins in food with high oil content, bilberry anthocyanins were acylated with cinnamic acids to address their poor lipid solubility. Structural analyses based on Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and 1H nuclear magnetic resonance analyses indicated that cinnamic acids were efficiently grafted onto 6-OH of glucoside and galactoside and 5-OH of arabinose through an esterification reaction. The higher the dose of the acylating agent, the higher the acylation degree (AD) and the lower the total anthocyanidin content (TAC) of bilberry anthocyanins. An-Ci4 presented the highest AD value (6.61%), and An-Ci3 exhibited the lowest TAC value (50.16 mg/g). After acylating with lipophilic cinnamic acids, the lipid solubility of acylated bilberry anthocyanins significantly improved. The color of the native bilberry anthocyanin solution dissolved in ethyl acetate and dioxane was transparent. By contrast, the acylated anthocyanin solution dissolved in these solvents was unmistakably red. In terms of the antioxidant activity, acylated bilberry anthocyanins demonstrated inferior performance in 2,2-diphenyl-1-picrylhydrazyl (DPPH) clearance but a better inhibition ratio in β-carotene bleaching assay compared with native bilberry anthocyanins. As AD value increased, the DPPH clearance of acylated anthocyanins decreased and their inhibition ratio increased in β-carotene bleaching assay.

Peroxisomal proliferation is highly stimulated during the biosynthesis of mycotoxins and plant infection by Fusarium graminearum. Currently, the functions of the peroxisome in these cellular processes are poorly understood. In this study, we applied genetic, cell biological and biochemical analyses to investigate the functions of the peroxisomes. We constructed targeted deletion of docking machinery components, including FgPex13, FgPex14 and the filamentous fungal specific peroxin FgPex33. Our results indicated that peroxisome dysfunction resulted in a shortage of acetyl-CoA, the precursor of trichothecene biosynthesis, and subsequently decreased deoxynivalenol (DON) production. Deletion mutants of ΔFgPex13, ΔFgPex14 or ΔFgPex33 showed an increased accumulation of endogenous reactive oxygen species (ROS) and reduced phosphorylation of MAP (Mitogen-Activated Protein) kinase FgMgv1. In addition, mutants of the docking peroxin exhibited increased sensitivity toward host oxidative bursts and cell wall integrity stress agents and reduced virulence on host plants. More importantly, we found for the first time that FgPex14 is required for pexophagy in F. graminearum. Overall, our study suggests that peroxisomes play critical roles in DON biosynthesis and virulence in F. graminearum.

Aim at improving the poor stability of natural anthocyanins applied in intelligent color indicator packing materials, anthocyanins from blueberry was acylated with maleic anhydride through means of solid-phase grafting method. Fourier Transform Infrared Spectroscopy (FTIR) analysis demonstrated that maleic acid was successfully grafted onto blueberry anthocyanins. All the four acylated anthocyanins (with different acylated degree) were better in stability, but were slightly less efficient at scavenging the DPPH radical, compared with their native non-acylated form. An-MA2 (acylated degree was 7.68%) got the lowest color loss (27.62% at 19th day), 23.19% lower than that of An-MA0 (native anthocyanins). After reacting with maleic anhydride, anthocyanins kept its pH-color response characteristics and showed distinct color differences at different pH value. In addition, the NH3 response characteristics of acylated anthocyanins were similar to those of non-acylated anthocyanins, but lagged slightly in response speed.

Deoxynivalenol (DON) is a mycotoxin produced in cereal crops infected with Fusarium graminearum. DON poses a serious threat to human and animal health, and is a critical virulence factor. Various environmental factors, including reactive oxygen species (ROS), have been shown to interfere with DON biosynthesis in this pathogen. The regulatory mechanisms of how ROS trigger DON production have been investigated extensively in F. graminearum. However, the role of the endogenous ROS‐generating system in DON biosynthesis is largely unknown. In this study, we genetically analysed the function of leucine zipper‐EF‐hand‐containing transmembrane 1 (LETM1) superfamily proteins and evaluated the role of the mitochondrial‐produced ROS in DON biosynthesis. Our results show that there are two Letm1 orthologues, FgLetm1 and FgLetm2, in F. graminearum. FgLetm1 is localized to the mitochondria and is essential for mitochondrial integrity, whereas FgLetm2 plays a minor role in the maintenance of mitochondrial integrity. The ΔFgLetm1 mutant demonstrated a vegetative growth defect, abnormal conidia and increased sensitivity to various stress agents. More importantly, the ΔFgLetm1 mutant showed significantly reduced levels of endogenous ROS, decreased DON biosynthesis and attenuated virulence in planta. To our knowledge, this is the first report showing that mitochondrial integrity and endogenous ROS production by mitochondria are important for DON production and virulence in Fusarium species.

Deoxynivalenol (DON) is a mycotoxin produced in cereal crops infected with Fusarium graminearum. DON poses a serious threat to human and animal health, and is a critical virulence factor. Various environmental factors, including reactive oxygen species (ROS), have been shown to interfere with DON biosynthesis in this pathogen. The regulatory mechanisms of how ROS trigger DON production have been investigated extensively in F. graminearum. However, the role of the endogenous ROS‐generating system in DON biosynthesis is largely unknown. In this study, we genetically analysed the function of leucine zipper‐EF‐hand‐containing transmembrane 1 (LETM1) superfamily proteins and evaluated the role of the mitochondrial‐produced ROS in DON biosynthesis. Our results show that there are two Letm1 orthologues, FgLetm1 and FgLetm2, in F. graminearum. FgLetm1 is localized to the mitochondria and is essential for mitochondrial integrity, whereas FgLetm2 plays a minor role in the maintenance of mitochondrial integrity. The ΔFgLetm1 mutant demonstrated a vegetative growth defect, abnormal conidia and increased sensitivity to various stress agents. More importantly, the ΔFgLetm1 mutant showed significantly reduced levels of endogenous ROS, decreased DON biosynthesis and attenuated virulence in planta. To our knowledge, this is the first report showing that mitochondrial integrity and endogenous ROS production by mitochondria are important for DON production and virulence in Fusarium species.