Linkage and QTL mapping in Cupressus sempervirens L. provides the first detailed genetic map of the species and identifies a QTLassociated with crown form

Cupressus sempervirens L. is a keystone species for Mediterranean ecosystems. It appears in two varieties according to its crown form, C. sempervirens var. horizontalis and C. sempervirens var. pyramidalis. A progeny of 382 F1 individuals was screened using Amplified Fragment Length Polymorphism (AFLP) and simple sequence repeats (SSR) markers for constructing genetic maps of the horizontalis and pyramidalis varieties used as parents, as well as a consensus map covering all chromosomes of the cypress genome. Out of the 1340 AFLP and SSR loci generated, 1271 variable loci segregated in 1:1, 3:1, 1:1:1:1, and 1:2:1 ratios and were used for linkage mapping. Segregation distortion was relatively high, but comparable to that reported in other Cupressaceae. The consensus C. sempervirens map (LOD = 6, θ = 0.30) consisted of 11 linkage groups and covered 2.105.65 cM. The consensus map was used for QTL detection regarding crown form, resistance to the fungus Seiridium cardinale, height, and diameter. A QTL for crown form architecture was found in linkage group 11 (LOD = 3.30). The long-term mapping population employed permits future map enrichment with more molecular markers, as well as more detailed records of quantitative traits at future ontogenetic stages. This is the first report of a consensus linkage map in a cypress species.