Cotton leafroll dwarf virus P0 protein is a silencing suppressor which inhibits local RNA silencing

DELFOSSE VC; AGROFOGLIO, YC; CASSE, MF; HOPP, HE; BONACIC KRESIC, I; ZIEGLER-GRAFF, V; DISTÉFANO, AJ

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Cotton leafroll dwarf virus (CLRDV) is a member of the Polerovirus genus from the Luteoviridae family that infects cotton, causing cotton-blue disease, and is transmitted by the Aphid gossypii. The P0 proteins of several poleroviruses were shown to possess a suppressor activity of post-trasncriptional gene silencing (PTGS). Here we examined the silencing suppressor activity of P0CLRDV. Agrobacterium-mediated co-infiltration of sense GFP with P0CLRDV in N. benthamiana line 16c. Which already has an integrated GFP transgene, led to the suppression of local PTGS, giving bright green infiltration spots at 5 days post-infiltration (dpi). However, P0CLRDV was not able to interfere with systemic spread of PTGS and the plants showed vein proximal silencing of GFP in systemic leaves at 14 dpi. In order to investigate the effect of P0CLRDV on RNA silencing triggered by double stranded RNA, we performed experiments infiltrating leaves of N. benthamiana with P0CLRDV, GFP and a dsRNA inducer GFFG deriving from the GFP gene, observing a suppressor phenotype. Silencing suppressor activity was also observed, in both systems, when P0CLRDV was expressed in the viral context by using a full-length infectious cDNA CLRDV clone. Northern blot analysis of GFP transcript levels and GFP-specific small interfering RNAs (21-24 nt) confirmed the visual observation that P0CLRDV mediate silencing suppression.