One new species and one new record of Zasmidium in China

A chromosome-level genome assembly of Zasmidium syzygii isolated from banana leaves

Accurate taxonomic classification of samples from infected host material is essential for disease diagnostics and genome analyses. Despite the importance, diagnosis of fungal pathogens causing banana leaf diseases remains challenging. Foliar diseases of bananas are mainly caused by 3 Pseudocercospora species, of which the most predominant causal agent is Pseudocercospora fijiensis. Here, we sequenced and assembled four fungal isolates obtained from necrotic banana leaves in Bohol (Philippines) and obtained a high-quality genome assembly for one of these isolates. The samples were initially identified as P. fijiensis using PCR diagnostics; however, the assembly size was consistently 30 Mb smaller than expected. Based on the internal transcribed spacer (ITS) sequences, we identified the samples as Zasmidium syzygii (98.7% identity). The high-quality Zasmidium syzygii assembly is 42.5 Mb in size, comprising 16 contigs, of which 11 are most likely complete chromosomes. The genome contains 98.6% of the expected single-copy BUSCO genes and contains 14,789 genes and 10.3% repeats. The 3 short-read assemblies are less continuous but have similar genome sizes (40.4-42.4 Mb) and contain between 96.5 and 98.4% BUSCO genes. All 4 isolates have identical ITS sequences and are distinct from Zasmidium isolates that were previously sampled from banana leaves. We thus report the first continuous genome assembly of a member of the Zasmidium genus, forming an essential resource for further analysis to enhance our understanding of the diversity of pathogenic fungal isolates as well as fungal diversity.

Allophoma species (Pleosporales: Didymellaceae) associated with Thunbergia grandiflora in Guangxi Province, China

Background

Thunbergiagrandiflora belongs to the family Acanthaceae and is a widely distributed dicotyledonous plant in tropical and subtropical regions. Three isolates of Allophoma (Dothideomycetes, Pleosporales, Didymellaceae) were collected from leaves of T.grandiflora in Guangxi Province, China.

New information

Phylogenetic analyses of a combined ITS–LSU–rpb2–tub2 dataset indicate that one of our three strains represents an undescribed species with close affinity to A.minor and the other two strains clustered amongst other isolates of A.pterospermicola. Evidence from morphology and sequence analysis indicates that GUCC 2070.7 is a new species that we introduce here as A.thunbergiae. This is the first report about taxa of Allophoma from this host plant.