Extracellular transmission of a DNA mycovirus and its use as a natural fungicide

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 4; pp. 1452 - 1457
• Main Authors: Yu, Xiao, Li, Bo, Fu, Yanping, Xie, Jiatao, Cheng, Jiasen, Ghabrial, Said A., Li, Guoqing, Yi, Xianhong, Jiang, Daohong
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 22.01.2013; National Acad Sciences
• Subjects: agar; Arabidopsis - microbiology; Arabidopsis - virology; Arabidopsis thaliana; Ascomycota; Ascomycota - pathogenicity; Ascomycota - virology; Base Sequence; Biological Control Agents; Biological Sciences; Botrytis cinerea; Brassica napus; Canola; cells; crop yield; Deoxyribonucleic acid; disease severity; DNA; DNA viruses; DNA Viruses - genetics; DNA Viruses - pathogenicity; DNA Viruses - physiology; DNA, Viral - genetics; Fungal infections; Fungi; Fungicides; Fungicides, Industrial; Genome, Viral; host range; Hyphae; Infections; Leaves; Life cycles; Mycoviruses; Pesticides; Plant Diseases - microbiology; Plant Diseases - prevention & control; Plants; Sclerotinia minor; Sclerotinia sclerotiorum; virion; Virions; Virology; Virulence; Viruses
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1213755110

Mycoviruses are thought not to be infectious as free particles and to lack an extracellular phase in their life cycles, limiting the broad use of hypovirulence-associated mycoviruses in controlling fungal disease. Here, we demonstrate that purified particles of a DNA mycovirus, Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), are infectious when applied extracellularly to its host Sclerotinia sclerotiorum . Virus particles isolated from an infected host can infect the hyphae of virus-free S. sclerotiorum directly when applied to hyphae grown on potato dextrose agar or sprayed on leaves of Arabidopsis thaliana and Brassica napus , regardless of vegetative compatibility affiliation. When applied to leaves, the virus can suppress the development of lesions. SsHADV-1 can also reduce disease severity and enhance rapeseed yield significantly under field conditions. SsHADV-1 has a narrow host range; it can infect Sclerotinia minor and Sclerotinia nivalis , sister species of S. sclerotiorum , and cause debilitation of these two fungi, but cannot infect or transfect other tested fungi, such as Botrytis cinerea , which shares the same family with S. sclerotiorum . Virus particles are likely to be very stable on the leaves of A. thaliana plants because viral DNA could be detected at 15 d postinoculation on unwounded leaves and at 10 d postinoculation on wounded leaves, respectively; however, this virus could not infect and move in plant cells. Our findings may prompt a reconsideration of the generalization that mycoviruses lack an extracellular phase in their life cycles and stimulate the search for other DNA mycoviruses with potential use as natural fungicides.