RNA2-encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post-transcriptional gene silencing
Author
Carpino, Caterina; Ferriol, Inmaculada; Elvira-González, Laura; Medina, Vicente; Rubio, Luis; Peri, Ezio; Davino, Salvatore; Galipienso, LuisDate
2020Cita bibliográfica
Carpino, C., Ferriol Safont, I., Elvira‐González, L., Medina, V., Rubio, L., Peri, E., ... & Galipienso Torregrosa, L. (2020). RNA2‐encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post‐transcriptional gene silencing. Molecular Plant Pathology, 21(11), 1421-1435.Abstract
Broad bean wilt virus 1 (BBWV-1, genus Fabavirus, family Secoviridae) is a bipartite,
single-stranded positive-sense RNA virus infecting many horticultural and ornamental
crops worldwide. RNA1 encodes proteins involved in viral replication whereas
RNA2 encodes two coat proteins (the large and small coat proteins) and two putative
movement proteins (MPs) of different sizes with overlapping C-terminal regions. In
this work, we determined the role played by the small putative BBWV-1 MP (VP37)
on virus pathogenicity, host specificity, and suppression of post-transcriptional gene
silencing (PTGS). We engineered a BBWV-1 35S-driven full-length cDNA infectious
clone corresponding to BBWV-1 RNA1 and RNA2 (pBBWV1-Wt) and generated a
mutant knocking out VP37 (pBBWV1-G492C). Agroinfiltration assays showed that
pBBWV1-Wt, as the original BBWV-1 isolate, infected broad bean, tomato, pepper,
and Nicotiana benthamiana, whereas pBBWV1-G492C did not infect pepper and tomato
systemically. Also, pBBWV1-G492C induced milder symptoms in broad bean
and N. benthamiana than pBBWV1-Wt. Differential retrotranscription and amplification
of the (+) and (−) strands showed that pBBWV1-G492C replicated in the agroinfiltrated
leaves of pepper but not in tomato. All this suggests that VP37 is a determinant
of pathogenicity and host specificity. Transient expression of VP37 through a potato
virus X (PVX) vector enhanced PVX symptoms and induced systemic necrosis associated
with programmed cell death in N. benthamiana plants. Finally, VP37 was identified
as a viral suppressor of RNA silencing by transient expression in N. benthamiana
16c plants and movement complementation of a viral construct based on turnip crinkle
virus (pTCV-GFP).