Identification and Characterization of mycovirus in Botrytis species

Abstract

Mycoviruses are common and have been reported to infect nearly all significant fungal taxonomic groupings. Mycovirus neo-lifestyles have been revealed by the identification and characterization of huge number of mycoviruses. This study reports an extensive screening survey on Pakistani Botrytis cinerea (Fungal) strains for the identification of viral infections. A sum of 102 Botrytis cinerea samples were screened, 9 isolates were found positive for mycoviral elements when analyzed by a classical dsRNA isolation method with an infection frequency of 8.8%. Six isolates (Kst5c, Kst10a, Kst14a, Kst31c, Kst32b & Kst33c) were subjected to Next-generation sequencing for virome analysis. A total of 27 mycoviruses were identified in the infected isolates, belonging to the families Endornaviridae, Fusariviridae, Botourmiavirdae, Narnaviridae and Mitoviridae. Based on the International Committee on Taxonomy of Viruses (ICTV) demarcation criteria, 4 identified mycoviruses are considered novel. Viruses from three isolates (Kst5c, Kst14a & Kst31c) were completely characterized and sequences have been submitted in the NCBI database. Isolate Kst31c was found to harbor infection of hypovirulent mycovirus (BcEV4) which shows debilitating effects in host fungus. Following genomic characterization, the biological assessment was also conducted in which mycovirus was successfully transferred from virus-infected (VI) strain to virus-free (VF) strain. Both said strains were vegetatively compatible because both belong to same genetic group (Group II). Genetic grouping of all the B. cinerea isolates was analyzed based on Bc-hch gene amplification followed by restriction digestion method. Isogenic lines were compared later on, virus infected strain showed persistent infections due to presence of mycovirus (BcEV4). Afterwards, pathogenicity tests were also performed which showed promising results