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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Crop Bioprotection Research » Research » Publications at this Location » Publication #311172

Title: Identification of double-stranded RNA viruses in Brazilian strains of Metarhizium anisopliae and their effects on fungal biology and virulence

item SANTOS, VIVIANE - Luiz De Queiroz College Of Agriculture (ESALQ)
item MASCARIN, GABRIEL - Embrapa
item DA SILVA LOPES, MARIANA - Luiz De Queiroz College Of Agriculture (ESALQ)
item FREGOLENTE ALVES, MARIA - Universidade De Campinas (UNICAMP)
item REZENDE, JANAYNE - Luiz De Queiroz College Of Agriculture (ESALQ)
item VICCARI GATTI, MARIA - Universidade De Campinas (UNICAMP)
item Dunlap, Christopher
item DELALIBER JUNIOR, ITALO - Luiz De Queiroz College Of Agriculture (ESALQ)

Submitted to: Plant Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2017
Publication Date: 1/11/2017
Citation: Santos, V., Mascarin, G.M., Da Silva Lopes, M., Fregolente Alves, M.C., Rezende, J.M., Viccari Gatti, M.S., Dunlap, C.A., Delaliber Junior, I. 2017. Identification of double-stranded RNA viruses in Brazilian strains of Metarhizium anisopliae and their effects on fungal biology and virulence. Plant Gene. 11:49-58.

Interpretive Summary: A collection of agriculturally important fungi were screened for the presence of viruses. While viruses that infect fungi are well known, very little is known about their impact on this class of fungi that are used to control insect pests. A collaborative study between researchers in Brazil and an ARS researcher in Peoria, IL, screened a collection of fungi used to control insect for the presence of viruses. The study demonstrated 61% of the isolates tested contained viruses. In addition, the impact of these viral infections on their virulence against insects was tested. The results showed the presence of the viruses had limited impact on the properties of the fungi. This work addresses a knowledge gap in understanding how viruses impact agriculturally important fungi. This work will ultimately benefit farmers and consumers by enhancing the options for insect pest control.

Technical Abstract: Brazil is the leading country in the use of the entomopathogenic fungus Metarhizium anisopliae against agricultural pests. Very little information has been documented about the diversity and the impact of mycoviruses on M. anisopliae sensu stricto. This study reports the diversity of mycoviruses associated with native Brazilian M. anisopliae isolates from the entomopathogen collection of the University of São Paulo, which are primarily from sugar-alcohol factories and commercial mycoinsecticides. We also investigated the potential effects of viral infection on the biological properties of the fungus. Double-stranded RNA viruses (dsRNA) were found in 61% of the 36 Metarhizium isolates and showed a large variation of 14 different electrophoretic banding patterns consisting of 2 to 8 dsRNA bands in polyacrylamide gels (PAGE). However, these mycoviruses were not detected in any of the commercial products used in this study. The different viral patterns found among these isolates have apparently no relation to the locations where they were collected. Efforts to “cure” isolates with dsRNA revealed that the inhibitor of protein synthesis cycloheximide was not efficient in eradicating dsRNA viruses from fungi. Colonies from both monoconidial culture and hyphal tip subcultures showed significant alterations in morphology; however, this variation was not correlated with the presence of mycoviruses. The dsRNA-variants of M. anisopliae isolates ESALQ 866, ESALQ 1256 and CTC F8 were healed after either monoconidial or hyphal tip subculturing. Clones of M. anisopliae ESALQ 1256 exhibited significant differences in vegetative growth, conidiospore production, and virulence against Tenebrio molitor larvae, although these differences were not related to dsRNA infections. Moreover, variants free or infected by dsRNA of this isolate showed similar heat and UV tolerance. In summary, our data indicate that dsRNA mycoviruses are very common among Brazilian M. anisopliae isolates, but there is no evidence that these viruses are associated with deleterious effects on these fungi.