Diverse, novel mycoviruses coinfecting the phytopathogenic fungus Corynespora cassiicola from Sesamum indicum

Introduction Corynespora leaf spot caused by Corynespora cassiicola is one of the most serious foliar diseases of sesame. Mycoviruses can infect various groups of fungi and have certain potential biocontrol value. However, the number of mycovirus reported in C. cassiicola is relatively scarce. Methods Seven strains of C. cassiicola isolated from Sesamum indicum were subjected to metatranscriptomic sequencing. Viral diversity was further assessed and validated through RT-PCR, followed by sequence alignment and phylogenetic analysis. Results A total of 19 viruses were identified across the seven strains, distributed among 12 families. +ssRNA viruses were identified, belonging to Botourmiaviridae (four viruses), Deltaflexiviridae (one virus), Fusariviridae (two viruses), Narnaviridae (two viruses), Ambiguiviridae (two viruses), and Potyviridae (one virus). −ssRNA viruses were assigned Mymonaviridaeto (two viruses), and Mycophioviridae (one virus). dsRNA viruses were found, including Chrysoviridae (one virus), Partitiviridae (one virus), Totiviridae (one virus), and Polymycoviridae (one virus). Discussion This study uses metatranscriptome technology to expand our understanding of the diversity of mycoviruses in C. cassiicola and provides a rich resource for future studies on mycovirus diversity and taxonomy.