Abstract
SummarySince their discovery, single‐domain antigen‐binding fragments of camelid‐derived heavy‐chain‐only antibodies, also known as nanobodies (Nbs), have proven to be of outstanding interest as therapeutics against human diseases and pathogens including viruses, but their use against phytopathogens remains limited. Many plant viruses including Grapevine fanleaf virus (GFLV), a nematode‐transmitted icosahedral virus and causal agent of fanleaf degenerative disease, have worldwide distribution and huge burden on crop yields representing billions of US dollars of losses annually, yet solutions to combat these viruses are often limited or inefficient. Here, we identified a Nb specific to GFLV that confers strong resistance to GFLV upon stable expression in the model plant Nicotiana benthamiana and also in grapevine rootstock, the natural host of the virus. We showed that resistance was effective against a broad range of GFLV isolates independently of the inoculation method including upon nematode transmission but not against its close relative, Arabis mosaic virus. We also demonstrated that virus neutralization occurs at an early step of the virus life cycle, prior to cell‐to‐cell movement. Our findings will not only be instrumental to confer resistance to GFLV in grapevine, but more generally they pave the way for the generation of novel antiviral strategies in plants based on Nbs.
Highlights
With well over 60 different viruses identified, grapevine (Vitis spp) is the crop with the highest number of infecting viruses (Martelli, 2014)
We demonstrate that resistance is effective against a wide range of Grapevine fanleaf virus (GFLV) isolates but not against Arabis mosaic virus (ArMV) and is due to the neutralization of the virus at the initial stage of the virus life cycle, prior to cell-to-cell movement
Nb23 recognizes a broad range of GFLV isolates but not ArMV
Summary
With well over 60 different viruses identified, grapevine (Vitis spp) is the crop with the highest number of infecting viruses (Martelli, 2014). The pathogenicity of all these viruses has not been established, a number of them are considered as severe grapevine pathogens such as the emerging Red blotch virus or Grapevine pinot gris virus or the well-described viruses responsible for rugose wood, leafroll and fanleaf degenerative diseases (Basso et al, 2017; Maliogka et al, 2015). The latter is often considered to be the most detrimental and widespread grapevine viral disease as it affects vineyards worldwide, in particular those of high-added value in which grapevine has been cultivated for centuries (Basso et al, 2017).
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