If breeders use a limited number of genes in their new resistant varieties, the
adaptive capacity of pathogenic populations will ultimately lead to more or less rapid
overcoming of these resistances, thus limiting the sustainability of their effectiveness.
Qualitative resistance is considered less durable than quantitative resistance since the
latter oppose less selection pressure on the pathogen and they are often governed by
several resistance genes. Quantitative disease resistance has been observed within
many crop plants but is not as well understood as qualitative (monogenic) disease
resistance and has not been used as extensively in breeding. Mapping quantitative trait
loci (QTLs) is a powerful tool for genetic dissection of quantitative disease resistance.
Keywords: Additive effect, Marker-Assisted Selection, Molecular markers
associated to QTLs, Quantitative trait loci (QTL), Resistance durability.
