Multiple mycoviruses identified in Pestalotiopsis spp. from Chinese bayberry

Chinese bayberry (Myrica rubra) is a subtropical fruit crop widely grown in southern China. Twig dieback is a disease of Chinese bayberry caused by Pestalotiopsis spp. and results in great economic losses to Chinese bayberry production. A virus survey was conducted in the population of Pestalotiopsis spp. infecting M. rubra in China. We explored the viral diversity in Pestalotiopsis spp., which may provide resources for further development as biocontrol agents of twig dieback.

Strains of Pestalotiopsis spp. were isolated from diseased twigs of M. rubra, and cultured on potato dextrose agar for RNA extraction. The total RNA of each strain was extracted, mixed, and used for RNA sequencing. The resulting sequences were deduplicated, annotated, and then used for phylogenetic analysis.

Seven novel viruses were characterized from 59 isolates of M. rubra collected from 14 localities in China. Based on the phylogenetic analysis, these viruses were classified into five viral families/orders, Botourmiaviridae, Mitoviridae, Partitiviridae, Tymovirales and Bunyavirales, and one virus, Pestalotiopsis negative-stranded RNA virus 1, which likely belongs to a new viral family.

Metatranscriptomics analysis showed the presence of various mycoviruses in Pestalotiopsis spp. isolated from M. rubra in China. The genomes of eight putative viruses were identified, seven of which were nearly full-length. Some of these viruses of Pestalotiopsis spp. may have the potential for the biological control of twig dieback of M. rubra.