The role of sugar transporters in the battle for carbon between plants and pathogens.

In photosynthetic cells, plants convert carbon dioxide to sugars that can be moved between cellular compartments by transporters before being subsequently metabolized to support plant growth and development. Most pathogens cannot synthesize sugars directly but have evolved mechanisms to obtain plant-derived sugars as C resource for successful infection and colonization. The availability of sugars to pathogens can determine resistance or susceptibility. Here, we summarize current progress on the roles of sugar transporters in plant-pathogen interactions. We highlight how transporters are manipulated antagonistically by both host and pathogens in competing for sugars. We examine the potential application of this target in resistance breeding and discuss opportunities and challenges for the future.

Complete genome sequencing of Hortaea werneckii M-3 for identifying polyester polyurethane degrading enzymes.

Hortaea werneckii M-3, a black yeast isolated from the marine sediment of the West Pacific, can utilize polyester polyurethane (PU, Impranil DLN) as a sole carbon source. Here, we present the complete genome of Hortaea werneckii M-3 with the focus on PU degradation enzymes. The total genome size is 38,167,921 bp, consisting of 186 contigs with a N50 length of 651,266 bp and a GC content of 53.06%. Genome annotation analysis predicts a total of 13,462 coding genes, which include 99 tRNAs and 105 rRNAs. Some genes encoding PU degrading enzymes including cutinase and urease are identified in this genome. The genome analysis of Hortaea werneckii M-3 will be helpful for further understanding the degradation mechanism of polyester PU by marine yeasts.

Magnetic covalent organic framework nanocomposites as a new adsorbent for the determination of polycyclic aromatic hydrocarbons in water and food samples.

A magnetic covalent organic framework nanocomposite (Fe3O4@COF(Tp-NDA)) was synthesized via a solvothermal method, used as a magnetic adsorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) from lake water, tea, coffee, and fried chicken, and detected using a high performance liquid chromatography-ultraviolet detector. The synthesized magnetic adsorbent was characterized via transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption-desorption isotherm analysis and vibrating sample magnetometry. Parameters that affected the extraction conditions and desorption conditions were optimized. Adsorption equilibrium could be attained within 3 min. The prepared magnetic material could be reused 10 times. The limits of detection and quantification were 0.05-0.25 µg L-1 and 0.17-0.83 µg L-1, respectively. The recovery was 74.6-101.8% with a relative standard deviation of below 4.2%. The method was successfully used to detect PAHs in various samples.

FgHtf1 Regulates Global Gene Expression towards Aerial Mycelium and Conidiophore Formation in the Cereal Fungal Pathogen Fusarium graminearum.

The homeobox gene family of transcription factors (HTF) controls many developmental pathways and physiological processes in eukaryotes. We previously showed that a conserved HTF in the plant-pathogenic fungus Fusarium graminearum, Htf1 (FgHtf1), regulates conidium morphology in that organism. This study investigated the mechanism of FgHtf1-mediated regulation and identified putative FgHtf1 target genes by a chromatin immunoprecipitation assay combined with parallel DNA sequencing (ChIP-seq) and RNA sequencing. A total of 186 potential binding peaks, including 142 genes directly regulated by FgHtf1, were identified. Subsequent motif prediction analysis identified two DNA-binding motifs, TAAT and CTTGT. Among the FgHtf1 target genes were FgHTF1 itself and several important conidiation-related genes (e.g., FgCON7), the chitin synthase pathway genes, and the aurofusarin biosynthetic pathway genes. In addition, FgHtf1 may regulate the cAMP-protein kinase A (PKA)-Msn2/4 and Ca2+-calcineurin-Crz1 pathways. Taken together, these results suggest that, in addition to autoregulation, FgHtf1 also controls global gene expression and promotes a shift to aerial growth and conidiation in F. graminearum by activation of FgCON7 or other conidiation-related genes.IMPORTANCE The homeobox gene family of transcription factors is known to be involved in the development and conidiation of filamentous fungi. However, the regulatory mechanisms and downstream targets of homeobox genes remain unclear. FgHtf1 is a homeobox transcription factor that is required for phialide development and conidiogenesis in the plant pathogen F. graminearum In this study, we identified FgHtf1-controlled target genes and binding motifs. We found that, besides autoregulation, FgHtf1 also controls global gene expression and promotes conidiation in F. graminearum by activation of genes necessary for aerial growth, FgCON7, and other conidiation-related genes.

The transcription factor FgMed1 is involved in early conidiogenesis and DON biosynthesis in the plant pathogenic fungus Fusarium graminearum.

Fusarium graminearum is a prominent fungal pathogen that causes economically important losses by infesting a wide variety of cereal crops. F. graminearum produces both asexual and sexual spores which disseminate and inoculate hosts. Therefore, to better understand the disease cycle and to develop strategies to improve disease management, it is important to further clarify molecular mechanisms of F. graminearum conidiogenesis. In this study, we functionally characterized the FgMed1, a gene encoding an ortholog of a conserved MedA transcription factor known to be a key conidiogenesis regulator in Aspergillus nidulans. The gene deletion mutants ΔFgMed1 produced significantly less conidia, and these were generated from abnormal conidiophores devoid of phialides. Additionally, we observed defective sexual development along with reduced virulence and deoxynivalenol (DON) production in ΔFgMed1. The GFP-tagged FgMed1 protein localized to the nuclei of conidiophores and phialides during early conidiogenesis. Significantly, RNA-Seq analyses showed that a number of the conidiation- and toxin-related genes are differentially expressed in the ΔFgMed1 mutant in early conidiogenesis. These data strongly suggest that FgMed1 involved in regulation of genes associated with early conidiogenesis, DON production, and virulence in F. graminearum.

Multiprotein-bridging factor 1 regulates vegetative growth, osmotic stress, and virulence in Magnaporthe oryzae.

Multiprotein bridging factor 1 (MBF1) is a transcriptional co-activator that mediates transcriptional activation by bridging sequence-specific activator like proteins and the TATA-box binding protein (TBP). MBF1 has been well-studied in Arabidopsis thaliana, Saccharomyces cerevisiae, Drosophila melanogaster, and Homo sapiens, but it is not well understood in filamentous fungi. In this study, we report the identification and characterization of a MBF1 ortholog (MoMBF1) in the rice blast fungus Magnaporthe oryzae), which causes the devastating rice blast disease and is an ideal model for studying the growth, development and pathogenic mechanisms of filamentous fungi. MoMBF1 encodes a 161 amino acid protein with a typical MBF1 domain and HTH domain. Bioinformatics were used to analyze the structural domains in MoMBF1 and its phylogenetic relationship to other homologs from different organisms. We have generated MoMBF1 deletion mutants (ΔMoMBF1) and functional complementation transformants, and found that the deletion mutants showed significant defects in vegetative growth and tolerance to exogenous stresses, such as 1 M sorbitol, 0.5 M NaCl, and 5 mM H2O2. Moreover, ΔMoMBF1 showed reduced pathogenicity with smaller infection lesions than wild type and the complementation strain, and decreased response to the accumulation of ROS (reactive oxygen species) in planta at the initial infection stage. Taken together, our data indicate that MoMBF1 is required for vegetative growth, pathogenicity and stress response in M. oryzae.