Bioactive Exopolysaccharides Reveal Camellia oleifera Infected by the Fungus Exobasidium gracile Could Have a Functional Use

The complete genome sequence of a novel mycovirus in the plant-pathogenic fungus Exobasidium gracile

The plant-pathogenic fungus Exobasidium gracile belongs to the basidiomycetous genus Exobasidium and causes leaf abnormalities in Camellia oleifera. Here, we report a novel mycovirus from E. gracile strain Z-2, called "Exobasidium gracile zybavirus 2" (EgZV2), which is related phylogenetically to a member of the genus Zybavirus in the family Amalgaviridae. Like those of other zybaviruses, the EgZV2 genome has two large open reading frames (ORFs) encoding an unknown protein and an RNA-dependent RNA polymerase (RdRp), respectively. In addition, we found a conserved +1 programmed ribosomal frameshifting (PRF) motif (UUUCGG) between ORF1 and ORF2 in EgZV2.

Molecular characterization of three novel mycoviruses in the plant pathogenic fungus Exobasidium

The plant pathogen Exobasidium gracile, which belongs to the basidiomycetous genus Exobasidium, can lead to swollen and thicker leaves of C. oleifera. To our knowledge, there have been no reports of mycoviruses infecting Exobasidium gracile. This study characterized three mycoviruses coinfecting the plant pathogen Exobasidium gracile strain Z-1. Based on phylogenetic and genomic analyses, E. gracile strain Z-1 was infected two putative Totiviruses designated Exobasidium gracile Totivirus 1 (EgTV1) and Exobasidium gracile Totivirus 2 (EgTV2) and a putative Zybavirus of the family Amalgaviridae defined Exobasidium gracile Zybavirus 1 (EgZV1). Similar to the genomic organization of other Totiviruses, the EgTV1 and EgTV2 genomes are composed of one dsRNA segment that exhibits two large ORFs encoding a CP (capsid protein) and an RdRp (RNA-dependent RNA polymerase), respectively. Moreover, EgTV1 and EgTV2 genomes with a candidate -1 slippery heptamer sequence were discovered between CP and RdRp, respectively. Similar to other Zybaviruses of the family Amalgaviridae, the EgZV1 genome is composed of one dsRNA segment that contains two large ORFs encoding an unknown protein and an RdRp. In addition, the EgZV1 genome has a candidate +1 slippery heptamer sequence between an unknown protein and RdRp.

Structural characterization and proliferation activity of chondroitin sulfate from the sturgeon, Acipenser schrenckii

The cartilages of marine fish, such as sharks and sturgeon, are important resources of the bioactive chondroitin sulfate (CS). To explore glycosaminoglycans from marine fish, polysaccharides from the cartilage of the sturgeon, Acipenser schrenckii, were extracted. Using enzyme-assisted extraction and anion-exchange chromatography, an uronic acid-containing polysaccharide, YG-1, was isolated. YG-1 is composed of GlcN, GlcUA, GalN, and Gal, in the ratio of 1.4: 3.4: 3.7: 1.0, and its molecular weight was determined to be 3.0 × 10⁵ Da. YG-1 was confirmed to be chondroitin 4-sulfate (CS) composed of →4GlcAβ1→3GalNAc4Sβ1→ and minor →4GlcAβ1→3GalNAcβ1→, which was confirmed using IR spectroscopy, disaccharide composition analysis, and NMR. Bioactivity studies, including MTT assay and scratch-wound assays revealed that CS from Acipenser schrenckii had significant proliferation activity. The proliferation activity of the polysaccharide, YG-1, was related to Fibroblast growth factor 2 (FGF2). GalNAc 4S of YG-1 could be the binding sites of FGF2 and FGFR.