Endophytic Fungus of Achyrocline satureioides: Molecular Identification, Chemical Characterization, and Cytotoxic Evaluation of its Metabolites in Human Melanoma cell line.

Endophytic fungi are important sources of anticancer compounds. An endophytic fungus was isolated from the medicinal plant Achyrocline satureioides, and molecularly identified as Biscogniauxia sp. (family Xylariaceae) based on partial nucleotide sequences of the internal transcribed spacer genomic region (GenBank Accession No. ON257911). The chemical characterization and cytotoxic properties of secondary metabolites produced by Biscogniauxia sp. were evaluated in a human melanoma cell line (A375). The fungus was grown in potato-dextrose liquid medium for 25 days, and the extracted compounds were subjected to solid-phase fractionation to obtain the purified FDCM fraction, for which the metabolites were elucidated via ultra-performance chromatography coupled to a mass spectrometer. In the present study, 17 secondary metabolites of Biscogniauxia sp., including nine polyketide derivatives, five terpenoids, and three isocoumarins, were putatively identified. This is the first study to report of the ability of Biscogniauxia sp. in the production of isocoumarin orthosporin; the terpenoids nigriterpene A and 10-xylariterpenoid; the polyketide derivatives daldinin C, 7'dechloro-5'-hydroxygriseofulvin, daldinone D, Sch-642305, curtachalasin A, cytochalasin E, epoxycytochalasins Z8, Z8 isomer, and Z17. Furthermore, this study has reported the biosynthesis of Sch-642305 by a Xylariaceae fungus for the first time. FDCM significantly reduced the viability and proliferation of human melanoma cells at half-maximal inhibitory concentrations ​​of 10.34 and 6.89 µg/mL, respectively, and induced late apoptosis/necrosis and cell cycle arrest in G2/M phase after 72 h of treatment. Given its ability to produce unique metabolites with promising cytotoxic effects, Biscogniauxia sp. of A. satureioides may be a reservoir of compounds with important therapeutic applications.

Characterization of the Complete Genome and P0 Protein for a Previously Unreported Genotype of Cotton Leafroll Dwarf Virus, an Introduced Polerovirus in the United States.

Virus-like disease symptoms consisting of leaf cupping, shortened internodes, and overall stunting were observed in commercial cotton fields in Alabama in 2017 to 2018. To determine the complete genome sequence of the suspected causal polerovirus, symptomatic leaf samples were collected in Macon County, Alabama, and subjected to Illumina RNA sequencing. Based on BLASTn analysis, the Illumina contig of 5,771 nt shared the highest nucleotide identity (approximately 95%) with members of the species Cotton leafroll dwarf virus (CLRDV) (genus Polerovirus; family Luteoviridae) from Argentina and Brazil. The full-length viral genome sequence was verified by reverse transcription (RT)-PCR amplification, cloning, and Sanger sequencing. The complete CLRDV genome of 5,865 nt in length shared 94.8 to 95.2% nucleotide identity with six previously reported CLRDV isolates. The genome of the CLRDV isolate amplified from Alabama samples (CLRDV-AL) has seven predicted open reading frames (ORFs). Viral proteins 1 to 5 (P1 to P5) shared 91.9 to 99.5% amino acid identity with the six CLRDV isolates from Argentina and Brazil. However, P0, the suppressor of host gene silencing, shared 82.4 to 88.5% pairwise amino acid identity with the latter CLRDV isolates. Phylogenetic analysis of the seven full-length CLRDV genomes resolved three sister clades: CLRDV-AL, CLRDV-typical, and CLRDV-atypical, respectively. Three recombination events were detected by the recombination detection program among the seven CLRDV isolates with breakpoints occurring along the genome. Pairwise nucleotide identity comparisons of ORF0 sequences for the three CLRDV-AL field isolates indicated that they were >99% identical, suggesting that this previously unknown CLRDV genotype represents a single introduction to Alabama.