Mycovirome of Diaporthe helianthi and D. gulyae, causal agents of Phomopsis stem canker of sunflower (Helianthus annuus L.)

Authors: WU, CHIEN-FU - The Ohio State University; Regedanz, Elizabeth; MATHEW, FEBINA - North Dakota State University; KASHYAP, RUCHIKA - University Of Georgia; MOHAN, KARTHIKA - North Dakota State University; Marzano, Shin-Yi

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2024
Publication Date: 12/31/2024
Citation: Wu, C., Regedanz, E.P., Mathew, F., Kashyap, R., Mohan, K., Marzano, S.L. 2024. Mycovirome of Diaporthe helianthi and D. gulyae, causal agents of Phomopsis stem canker of sunflower (Helianthus annuus L.). Virus Research. 351 Article 199521. https://doi.org/10.1016/j.virusres.2024.199521.
DOI: https://doi.org/10.1016/j.virusres.2024.199521

Interpretive Summary: The causal agents of Phomopsis stem canker on sunflower are Diaporthe gulyae and D. helianthi. In this study, we used a metatranscriptome approach to discover 19 novel mycoviruses infecting the Diaporthe isolates from diseased sunflower plants. The results show a phylogenetically diverse group of viruses, and some of the fungal isolates harboring viruses exhibiting debilitated growth, possibly due to the mycovirus infection, and some of could have cross-kingdom infectivity with insects.

Technical Abstract: Diaporthe gulyae and D. helianthi cause Phomopsis stem canker, which is a yield-limiting fungal disease of sunflower (Helianthus annuus L.) in the United States. In this study, the mycovirus population was characterized in D. gulyae and D. helianthi using 52 and 42 isolates, respectively, that were recovered from diseased sunflower plants randomly sampled from commercial sunflower fields in the U.S. states of Minnesota, Nebraska, North Dakota, and South Dakota. Total RNA extracts depleted of rRNA from each fungus were pooled to construct one library for sequencing to obtain 20 GB per library of raw reads using a metatranscriptomics approach. Between the two libraries, they only share one mycovirus in high amounts. Twelve and ten novel viral contigs were discovered infecting D. gulyae and D. helianthi, respectively, along with a plant virus contig that was detected as Cucumber green mosaic virus coat protein, indicating trans-kingdom transmission of the same viruses. Additionally, we detected two of the same viruses infecting D. helianthi, Helianthus annuus leaf-associated partitivirus 3 and 5, that were detected in a direct sunflower metatranscriptome reported before. Interestingly, Qinvirus, which is mostly known as a group of insect viruses, was found in a contig. Surprisingly, a short contig of Fusarium graminearum virus-1 SD4 was also detected, indicating that intergeneric transmission of the viruses may exist. Besides an understanding of virome diversity, the mycovirome survey provides the first clue of biological molecules that can be further developed for antifungal purposes.