Characterization of different pepper resistances to Potato virus Y through quantitative approaches to measure viral load

Plant resistance to viruses can target different stages of the virus cycle like the inoculation, the accumulation and cell to cell movement, the systemic colonization and the virus ingestion by a vector. Among them, virus accumulation in plants can be inhibited or diminished by different resistance mechanisms. Even if they are well characterized at the molecular level, the evaluation of the phenotypic expression of these resistances requires the development of specific methods. Based on the pathosystem pepper-Potato virus Y (PVY), this work relies on 3 methods for the quantitative measure of virus accumulation in plants: ELISA, RT-qPCR and fluorescence imaging. The major result is the identification of a significant correlation between the proportion of fluorescent surface area measured by fluorescent imaging (and linked to the expression of a GFP protein stuck on the virus) and the concentration of coat proteins measured by semi-quantitative ELISA. In addition, the use of fluorescent imaging (a non-destructive method) allowed the monitoring of viral accumulation in different pepper accessions and highlighted contrasted kinetics in a susceptible and a resistant cultivar.