# Effect of mutations in intrinsically-disordered or ordered regions of potato virus Y (PVY; genus Potyvirus; family Potyviridae) VPg on virus fitness and adaptability

Guillaume Dubrulle, Guillaume Lafforgue, Justine Charon, Amandine Barra, Marion Szadkowski, Lola Chateau, Cecile Desbiez, Thierry Michon, Benoît Moury

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Guillaume Dubrulle, Guillaume Lafforgue, Justine Charon, Amandine Barra, Marion Szadkowski, et al.. Effect of mutations in intrinsically-disordered or ordered regions of potato virus Y (PVY; genus Potyvirus; family Potyviridae) VPg on virus fitness and adaptability. 20. Rencontres de virologie végétale (RVV 2025), Jan 2025, Aussois, France. hal-05147646

HAL Id: hal-05147646

https://hal.inrae.fr/hal-05147646v1

Submitted on 7 Jul 2025

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Effect of mutations in intrinsically-disordered or ordered regions of potato virus Y (PVY ; genus Potyvirus ; family Potyviridae) VPg on virus fitness and adaptability

Guillaume Dubrulle<fnref n="1" /> (guillaume.dubrulle@univ-reims.fr), Guillaume Lafforgue<fnref n="2" />, Justine Charon<fnref n="2" />, Amandine Barra<fnref n="2" />, Marion Szadkowski<fnref n="1" />, Lola Chateau<fnref n="1" />, Cécile Desbiez<fnref n="1" />, Thierry Michon<fnref n="2" />, Benoit Moury<fnref n="1" />

Viruses display a particularly high number of intrinsically-disordered regions (IDR) within their proteins. Intrinsic disorder can be beneficial to the fitness and evolutionary potential of viruses. We have previously shown (Charon et al. 2018) that mutations in the VPg of PVY that increase the level of intrinsic disorder have a positive effect on PVY adaptability in pepper and that a mutation that decreases the level of intrinsic disorder has a negative effect on PVY adaptability. However, few mutations were tested and only one VPg domain was mutated, with a dual function affecting both intrinsic disorder and interaction with the plant resistance factor.

Here, we tested whether random mutations spanning the entire VPg differ in their effect on PVY fitness and adaptability, depending on whether they occur in the intrinsically disordered or ordered regions of the VPg. To test this hypothesis, we will present, for 15 PVY mutants, (i) measures of intra-plant accumulation, symptoms and impact of infection on plant weight in the susceptible pepper genotype Yolo Wonder and (ii) infection efficiencies of pepper genotype HD285, carrying resistance gene *pvr23* (as a measure of adaptability). Of these 15 mutants, only one showed a higher accumulation than the wild-type PVY strain, and only two had a higher adaptability. Fourteen mutants induced a lower reduction of plant weight than the wild-type.

Globally, these data do not support the hypothesis that mutations in intrinsically-disordered regions increase virus fitness or adaptability.

Mots clés : Intrinsic disorder - Protein structure - Fitness - Evolvability.

Références :

1. Charon J, Barra A, Walter J, Millot P, Hébrard E, Moury B, Michon T. 2018. First Experimental Assessment of Protein Intrinsic Disorder Involvement in an RNA Virus Natural Adaptive Process. Mol Biol Evol 35:38-49.

<footnote n="1">¹ Pathologie végétale, INRAE, Montfavet, France</footnote>

<footnote n="2">² UMR Biologie du Fruit et Pathologie, INRAE, Université de Bordeaux, Villenave-d'Ornon, France</footnote>