The inheritance of bract pigmentation and fleshy thorns on the globe artichoke capitulum

The bracts of the globe artichoke inflorescence vary in their pigmentation and the extent of fleshy thorn development. Here, a genetic analysis of these two traits is presented, based on a pre-existing and well-characterized mapping population derived from a cross between a globe artichoke variety and a cultivated cardoon. While both traits appeared to be simply inherited when the number of trait classes was limited to three (pigmentation) or two (thorniness), extending the classification to a larger number of states generated continuous distributions appropriate for a quantitative trait locus (QTL) analysis. The seven QTL identified by this means, mapping to five different linkage groups, were all expressed across two growing seasons. The largest effect QTL mapped onto homologues linkage group in each parental maps, and explained up to 69% and 73% of the phenotypic variance respectively for bracts pigmentation and thorniness.