Interannual dynamics, diversity and evolution of the virome in <i>Sclerotinia sclerotiorum</i> from a single crop field

Abstract

Mycovirus diversity is generally analyzed from isolates of fungal culture isolates at a single point in time as a snapshot. The stability of mycovirus composition within the same geographical location over time remains unclear. Not knowing how the population fluctuates in the field can be a source of unpredictability in the successful application of virocontrol. To better understand the changes over time, we monitored the interannual dynamics and abundance of mycoviruses infecting <i>Sclerotinia sclerotiorum</i> at a rapeseed-growing field for three years. We found that the virome in <i>S. sclerotiorum</i> harbors unique mycovirus compositions each year. In total, sixty-eight mycoviruses were identified, among which twenty-four were detected in all three successive years. These twenty-four mycoviruses can be classified as the members of the core virome in this <i>S. sclerotiorum</i> population, which show persistence and relatively high transmissibility under field conditions. Nearly two-thirds of the mycoviruses have positive-sense, single-stranded RNA genomes and were found consistently across all three years. Moreover, twenty-eight mycoviruses are newly described, including four novel, multi-segmented narnaviruses, and four unique bunyaviruses. Overall, the newly discovered mycoviruses in this study belong to as many as twenty families, into which eight were first identified in <i>S. sclerotiorum</i>, demonstrating evolutionarily diverse viromes. Our findings not only shed light on the annual variation of mycovirus diversity but also provide important virus evolutionary clues.