Diverse suppressors of RNA silencing enhance agroinfection by a viral replicon

• Published in: Virology (New York, N.Y.) N.Y.), 2006-03, Vol.346 (1), p.7-14
• Main Authors: Chiba, Marin, Reed, Jonathan C., Prokhnevsky, Alexey I., Chapman, Elisabeth J., Mawassi, Munir, Koonin, Eugene V., Carrington, James C., Dolja, Valerian V.
• Format: Article
• Language: English
• Subjects: Agrobacterium tumefaciens; Agroinfection; Amino Acid Sequence; amino acid sequences; Beet yellows virus; Closterovirus - genetics; Closterovirus - metabolism; Closterovirus - pathogenicity; conserved sequences; DNA, Viral - genetics; genetic transformation; genetic vectors; Grapevine leafroll-associated virus; Grapevine virus A; Molecular Sequence Data; Nicotiana - virology; Plant Leaves - virology; plant viruses; replicon; Replicon - genetics; Replicon - physiology; Rhizobium - genetics; RNA Interference; RNA silencing; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; RNA-Binding Proteins - chemistry; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; viral proteins; Viral Proteins - genetics; Viral Proteins - metabolism; Viral suppressors; Vitaceae
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2005.09.068

Launching the Beet yellows virus (BYV) minireplicon by agrobacterial delivery resulted in an unexpectedly low number of infected cells per inoculated leaf. This effect was due to a strong RNA silencing response in the agroinfiltrated leaves. Strikingly, ectopic co-expression of p21, a BYV RNA silencing suppressor, increased minireplicon infectivity by three orders of magnitude. Mutational analysis demonstrated that this effect correlates with suppressor activity of p21. Five diverse, heterologous viral suppressors were also active in this system, providing a useful approach for a dramatic, up to 10,000-fold, increase of the efficiency of agroinfection. The minireplicon agroinfection assay was also used to identify a new suppressor, a homolog of BYV p21, derived from Grapevine leafroll-associated virus-2. In addition, we report preliminary data on the suppressor activity of the p10 protein of Grapevine virus A and show that this protein belongs to a family of Zn-ribbon-containing proteins encoded by filamentous plant RNA viruses from three genera. The members of this family are predicted to have RNA silencing suppressor activity.