Wei-Jun Duan

Plenodomus lindquistii (basionym: Leptosphaeria lindquistii) is the most prevalent fungus pathogen causing the black stem disease in sunflower. To date, only one whole-genome sequence is reported in NCBI, but no complete gene annotation has been submitted. Herein, we sequenced a Leptosphaeria lindquistii isolate from sunflower seeds imported from the United States using Oxford Nanopore long-read sequencing and Illumina short-read sequencing. We generated a 38.6-Mb genome assembly consisting of 29 contigs with an N50 of 1.689 Mb and a maximum length of 5.316 Mb. In the genome assembly, we identified 13,481 protein-coding genes, of which 12,531 were annotated. The high-quality assembly and annotation of the Leptosphaeria lindquistii genome will allow us to conduct further studies for the specific identification of pathogens causing sunflower black stem disease and provide a better understanding of the infection mechanisms of Leptosphaeria lindquistii.

The Fusarium incarnatum-equiseti species complex (FIESC) is shown to encompass 33 phylogenetic species, across a wide range of habitats/hosts around the world. Here, 77 pathogenic and endophytic FIESC strains collected from China were studied to investigate the phylogenetic relationships within FIESC, based on a polyphasic approach combining morphological characters, multi-locus phylogeny and distribution patterns. The importance of standardised cultural methods to the identification and classification of taxa in the FIESC is highlighted. Morphological features of macroconidia, including the shape, size and septum number, were considered as diagnostic characters within the FIESC. A multi-locus dataset encompassing the 5.8S nuclear ribosomal gene with the two flanking internal transcribed spacers (ITS), translation elongation factor (EF-1α), calmodulin (CAM), partial RNA polymerase largest subunit (RPB1) and partial RNA polymerase second largest subunit (RPB2), was generated to distinguish species within the FIESC. Nine novel species were identified and described. The RPB2 locus is demonstrated to be a primary barcode with high success rate in amplification, and to have the best species delimitation compared to the other four tested loci.