First Report of Mycovirus Infected Sclerotinia sclerotiorum in Cauliflower from Sirmaur District of Himachal Pradesh

Background: Sclerotinia sclerotiorum is a ubiquitous fungal pathogen infecting more than 400 plant species. Sclerotinia stem rot is known to cause as high as 100% crop loss in many cases. Currently, chemical fungicides are the only known solution to this problem. Thus, there is an urgent need for developing environment-friendly alternatives for controlling this pathogen. The review of published articles revealed that a number of mycoviruses with the potential of a biocontrol agent against Sclerotinia had been identified from different parts of the world. Objective: The present investigation describes the isolation and characterization of isolates of S. sclerotiorum infecting cauliflower, peas, and mustard for the presence of a potent mycovirus from lower Himachal region of India. Methods: Various infected fields were visited and samples in the form of sclerotia were collected. Various isolates of S. sclerotiorum were obtained, and putative hypovirulent isolates were screened. Thereafter, hypovirulent strains were chosen and mycovirus isolation was performed. Finally, isolates showing an extra nucleic acid band were used for mycovirus isolation and further characterization. Curing of mycovirus was used to confirm if altered phenotype was due to the presence of this virus. Results: A ssDNA mycovirus was identified and confirmed from the growth defective isolate. Conclusion: This mycovirus can in turn act as a biocontrol agent, thus reducing dependency on chemical fungicides and can also be developed in the form of a patent once completely characterized and formulated. To our knowledge, this is the first report on mycovirus isolation from any Sclerotinia sclerotiorumisolate from India.