Expression of the p24 silencing suppressor of Grapevine leafroll-associated virus 2 from Potato virus X or Barley stripe mosaic virus vector elicits hypersensitive responses in Nicotiana benthamiana

Probing into the Effects of Grapevine Leafroll-Associated Viruses on the Physiology, Fruit Quality and Gene Expression of Grapes

“…Viruses of the Crinivirus genus also have a small ORF that is located between the ORFs for p60 and CP of the QGB, which is unique to the Crinivirus genus (Figure 1D) [15]. While the function of the small protein encoded by this extra ORF remains unknown, it has been shown that p9 of lettuce infectious yellows virus (LIYV) self-interacts [16], which is characteristic of RNA silencing suppressors (RSS) encoded by different viruses [17][18][19]. In line with this, it has been reported that p9 is required for establishing efficient infection and pathogenicity [20].…”

“…Each of these proteins encoded by the 3 terminal ORF in their corresponding viruses has been demonstrated to function as a RSS [73][74][75]. GLRaV-2 p24 induces systemic necrosis in N. benthamiana when expressed via a potato virus X (PVX) vector and local necrosis via a vector based on barley stripe mosaic virus (BSMV) [18]. A recent study suggests that p24 may function by directly binding siRNAs thereby preventing their incorporation into RNA-induced silencing complex (RISC) [17].…”

Viral suppressors from members of the family Closteroviridae combating antiviral RNA silencing: a tale of a sophisticated arms race in host-pathogen interactions

“…The p24 protein of GLRaV-2 is a strong VSR encoded by a cryptic ORF in the viral genome. It can effectively block siRNA accumulation and suppress antiviral RNA silencing (Wang et al 2019). The N-terminus (amino acids 1-188) of p24 is a main functional region, comprising all predicted α-helicases and β-strands that are most essential for its VSR activity.…”

Application of Plant Viruses in Biotechnology, Medicine, and Human Health

“…PVX used as an expression vector for the production of V2, C1, and C4 proteins of a novel monopartite begomovirus, the Ageratum leaf curl Sichuan virus in N. benthamiana Deletion and mutational analysis of the C4 protein using this PVX-derived vector showed that C4 is the major pathogenicity determinant which impacted symptom expression and virus accumulation [113] Phytophthora sojae virulence effector Avh148 expressed in plants using a PVX-based vector and a virus-induced virulence effector (VIVE) assay to detect putative effectors encoded by various plant pathogens This PVX-Avh148 vector infected plants with strong viral symptoms and led to elevated levels of Avh148 effector and viral RNA accumulation; Avh148 was found to be essential for full pathogenic virulence; this VIVE assay could detect putative effectors encoded by various plant pathogens including even unculturable pathogens using this PVX-based expression vector [114] Grapevine leafroll-associated virus 2 (GLRaV-2) encodes a p24 polypeptide (a suppressor of RNA-silencing) that was expressed in a PVX-based vector p24 causes systemic necrosis in N. benthamiana wherein a cytoplasmic Zn2+-binding protein, NbRAR1 is involved and the symptoms are characteristic of a hypersensitive response; the essential role of p24 in GLRaV-2 pathogenesis was elucidated using the PVX expression vector wherein both silencing suppression and p24 self-interaction are critical for the pathogenic activity of p24 [115] Tomato torrado virus (ToTV) capsid protein subunits Vp23, Vp26, and Vp35 expressed transiently from a PVX-derived vector in Solanum lycopersicum Of these, Vp26 protein was shown to be the necrosis and pathogenicity determinant responsible for severe systemic necrosis of the plants accompanied by increased ribonuclease and oxidative activities [116] PVX has been developed as a VIGS vector in potatoes wherein VIGS mediates silencing of endogenous plant genes, thus helping to investigate the functions of the silenced genes…”