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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.00976

Roles of argonautes and dicers on Sclerotinia sclerotiorum antiviral RNA silencing

 Shin-Yi Lee Marzano1*,  Achal Neupane1, Pauline Mochama1, Chenchen Feng1 and Huma Saleem1
  • 1South Dakota State University, United States

RNA silencing or RNA interference (RNAi) is an essential mechanism in animals, fungi, and plants that functions in gene regulation and defense against foreign nucleic acids. In fungi, RNA silencing has been shown to function primarily in defense against invasive nucleic acids. We previously determined that mycoviruses are triggers and targets of RNA silencing in Sclerotinia sclerotiorum. However, recent progresses in RNAi or dsRNA-based pest control requires more detailed characterization of the RNA silencing pathways in S. sclerotiorum to investigate the utility of dsRNA-based strategy for white mold control. This study elucidates the roles of argonaute enzymes, agl-2 and agl-4, in small RNA metabolism in S. sclerotiorum. Gene disruption mutants of agl-2 and agl-4 were compared for changes in phenotype, virulence, viral susceptibility, and small RNA profiles. The ∆agl-2 mutant but not the ∆agl-4 mutant had significantly slower growth and virulence prior to virus infection. Similarly, the ∆agl-2 mutant but not the ∆agl-4 mutant, showed greater debilitation under virus infection compared to uninfected strains. The responses were confirmed in complementation studies and revealed the antiviral role of agl-2. Gene disruption mutants of agl-2, agl-4, Dicer-like (dcl)-1 and dcl-2 did not change the stability of the most abundant endogenous small RNAs, which suggests the existence of alternative enzymes/pathways for small RNA biogenesis in S. sclerotiorum. Furthermore, in vitro synthesized dsRNA targeting agl-2 showed a significantly reduced average lesion diameter (P<0.05) on canola leaves with agl-2 down-regulated compared to controls. This is the first report describing the effectiveness of RNA pesticides targeting S. sclerotiorum RNA silencing pathway for the control of the economically important pathogen.

Keywords: Argonautes (AGO), dicer, Mycovirus, RNA silencing pathway, DsRNA (double-stranded RNA), RNA pesticide

Received: 01 Feb 2019; Accepted: 11 Jul 2019.

Edited by:

Daohong Jiang, Huazhong Agricultural University, China

Reviewed by:

Attila Molnar, University of Edinburgh, United Kingdom
CARMEN HERNANDEZ, Institute of Molecular and Cellular Biology of Plants, Polytechnic University of Valencia, Spain  

Copyright: © 2019 Lee Marzano, Neupane, Mochama, Feng and Saleem. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Shin-Yi Lee Marzano, South Dakota State University, Brookings, United States, sylee1110@yahoo.com