Diversity of genetic backgrounds modulating the durability of a major resistance gene. Analysis of a core collection of pepper landraces resistant to Potato virus Y.

The evolution of resistance-breaking capacity in pathogen populations has been shown to depend on the plant genetic background surrounding the resistance genes. We evaluated a core collection of pepper (Capsicum annuum) landraces, representing the worldwide genetic diversity, for its ability to modulate the breakdown frequency by Potato virus Y of major resistance alleles at the pvr2 locus encoding the eukaryotic initiation factor 4E (eIF4E). Depending on the pepper landrace, the breakdown frequency of a given resistance allele varied from 0% to 52.

Quantitative trait loci from the host genetic background modulate the durability of a resistance gene: a rational basis for sustainable resistance breeding in plants.

The combination of major resistance genes with quantitative resistance factors is hypothesized as a promising breeding strategy to preserve the durability of resistant cultivar, as recently observed in different pathosystems. Using the pepper (Capsicum annuum)/Potato virus Y (PVY, genus Potyvirus) pathosystem, we aimed at identifying plant genetic factors directly affecting the frequency of virus adaptation to the major resistance gene pvr2(3) and at comparing them with genetic factors affecting quantitative resistance. The resistance breakdown frequency was a highly heritable trait (h(2)=0.

Potato virus Y: a major crop pathogen that has provided major insights into the evolution of viral pathogenicity.

Taxonomy: Potato virus Y (PVY) is the type member of the genus Potyvirus in the family Potyviridae. VIRION AND GENOME PROPERTIES: PVY virions have a filamentous, flexuous form, with a length of 730 nm and a diameter of 12 nm. The genomic RNA is single stranded, messenger sense, with a length of 9.

Farther, slower, stronger: how the plant genetic background protects a major resistance gene from breakdown.

Genetic resistance provides efficient control of crop diseases, but is limited by pathogen evolution capacities which often result in resistance breakdown. It has been demonstrated recently, in three different pathosystems, that polygenic resistances combining a major-effect gene and quantitative resistance controlled by the genetic background are more durable than monogenic resistances (with the same major gene in a susceptible genetic background), but the underlying mechanisms are unknown. Using the pepper-Potato virus Y system, we examined three mechanisms that could account for the greater durability of the polygenic resistances: (i) the additional quantitative resistance conferred by the genetic background; (ii) the increase in the number of mutations required for resistance breakdown; and (iii) the slower selection of adapted resistance-breaking mutants within the viral population.