Abstract
BackgroundThe 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.ResultsA 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.ConclusionThe 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.
Highlights
The Asteraceae species Cynara cardunculus (2n = 2x = 34) includes the two fully cross-compatible domesticated taxa globe artichoke and cultivated cardoon
Co-dominant markers appear to be less affected by segregation distortion than dominant ones [23,24], and this certainly was the case for C. cardunculus, where ~13% of AFLP and S-SAP loci [17], but only ~5% of SSRs and SNPs are distorted
We have reported here an extension of the C. cardunculus genetic map by introducing SSR loci sited within genic sequence
Summary
The Asteraceae species Cynara cardunculus (2n = 2x = 34) includes the two fully cross-compatible domesticated taxa globe artichoke The Asteraceae (ex Compositae) species Cynara cardunculus L. comprises three taxa, namely the two domesticated form globe artichoke The cultivated cardoon is exclusively seedpropagated, and is generally handled as an annual crop Of late it has been promoted as a source of lignocellulosic biomass [10,11,12] and the evidence suggests that it should be possible to derive types able to flower early, to produce stems with a high lignin content and to generate biomass with a good level of energy efficiency [13,14]. Earliness is an important trait in both domesticated forms
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