title: Genetic mapping and identification of QTL for earliness in the globe artichoke/cultivated cardoon complex.
abstract: BACKGROUND
  The Asteraceae species Cynara cardunculus (2n = 2x = 34) includes the two fully cross-compatible domesticated taxa globe artichoke (var. scolymus L.) and cultivated cardoon (var. altilis DC). As both are out-pollinators and suffer from marked inbreeding depression, linkage analysis has focussed on the use of a two way pseudo-test cross approach.
  
  
  RESULTS
  A set of 172 microsatellite (SSR) loci derived from expressed sequence tag DNA sequence were integrated into the reference C. cardunculus genetic maps, based on segregation among the F1 progeny of a cross between a globe artichoke and a cultivated cardoon. The resulting maps each detected 17 major linkage groups, corresponding to the species' haploid chromosome number. A consensus map based on 66 co-dominant shared loci (64 SSRs and two SNPs) assembled 694 loci, with a mean inter-marker spacing of 2.5 cM. When the maps were used to elucidate the pattern of inheritance of head production earliness, a key commercial trait, seven regions were shown to harbour relevant quantitative trait loci (QTL). Together, these QTL accounted for up to 74% of the overall phenotypic variance.
  
  
  CONCLUSIONS
  The newly developed consensus as well as the parental genetic maps can accelerate the process of tagging and eventually isolating the genes underlying earliness in both the domesticated C. cardunculus forms. The largest single effect mapped to the same linkage group in each parental maps, and explained about one half of the phenotypic variance, thus representing a good candidate for marker assisted selection.
authors.affiliation: DiVaPRA Plant Genetics and Breeding, University of Torino, Grugliasco, Torino, Italy.
authors.forename: Ezio
authors.initials: E
authors.lastname: Portis
authors.forename: Davide
authors.initials: D
authors.lastname: Scaglione
authors.forename: Alberto
authors.initials: A
authors.lastname: Acquadro
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mauromicale
authors.forename: Rosario
authors.initials: R
authors.lastname: Mauro
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Knapp
authors.forename: Sergio
authors.initials: S
authors.lastname: Lanteri
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D031942:Cynara / Q000235:genetics* / Q000254:growth & development; D031943:Cynara scolymus / Q000235:genetics* / Q000254:growth & development; D018744:DNA, Plant / Q000032:analysis*; D020224:Expressed Sequence Tags; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D008040:Genetic Linkage; D005838:Genotype; D006238:Haploidy; D040582:Inheritance Patterns; D018895:Microsatellite Repeats; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci
chemical_list: D018744:DNA, Plant