Licensed to Silence: Search for the Host Defense Silencer in Cassava Torrado-like Virus

Primary author: Jenyfer Jimenez
Co-author(s): Ying Zhai

Primary college/unit: Agricultural, Human and Natural Resource Sciences
Campus: Pullman


Cassava (Manihot esculenta Crantz, Euphorbiaceae) is an important staple food crop for Africa, Asia and Latin America. Cassava torrado-like virus (CsTLV, Family Secoviridae), is found in mixed virus infections associated with severe disease symptoms in leaves and roots of CsTLV, a major viral pathogen of cassava, has been reported in Argentina, Colombia, and Peru. Virus infection leads to significant reduction in the accumulation of total sugars in cassava storage roots. While CsTLV has become an important constraint to cassava production, little is known about how the virus evades the host defense. A better understanding of the virus biology and molecular biology would lead to improved diagnostics which are critical in producing virus-free, clean planting material.
Plant viruses encode RNA silencing suppressors (RSS) to counteract the RNA silencing-based plant defense system. However, no such RSS has been identified in torradoviruses. To further advance the characterization of CsTLV, we first used bioinformatics software to identify the candidate genes for functional characterization of virally coded RNA silencing suppression. Viral coat protein genes were cloned and each gene was separately expressed using agroinfiltration in transgenic Nicotiana benthamiana line 16c plants, using the green fluorescent protein as the visual reporter/marker.
Results indicated that none of the three different coat protein genes from CsTLV showed RSS activity. Future studies will include testing for RSS activity of the three coat protein genes in different combinations.