The phylogenetic relationship between different Cichorium intybus cultivars and cultivar groups, as revealed by RAPDs

The phylogenetic relationship between different Cichorium intybus cultivars and cultivar groups was studied. A total of 127 random amplified polymorphic DNA markers have been used to distinguish between 51 Cichorium intybus cultivars belonging to three different cultivar groups. A principal component analysis was performed on the complete data set and a clear grouping of chicory cultivar groups was observed. The three chicory groups tested (root chicory, witloof and pain de sucre) were separated from one another in the principal component plots. The first two axes accounted for 43.9% of the total variation. Although the chicory used in traditional forcing in soil and the red chicory cultivars were related more to each other and to the chicory cultivars from the witloof group, they still formed separate groups in the principal component plot.     

Identification of commercial chicory cultivars for hydroponic forcing and their phenetic relationships revealed by random amplified polymorphic DNAs and amplified fragment length polymorphisms

One‐hundred and twenty‐four amplified fragment length polymorphism (AFLP) and 49 random amplified polymorphic DNA (RAPD) markers have been used to distinguish between 20 and 23 commercial chicory cultivars, respectively. These were all Cichorium intybus var. foliosum F₁ hybrids, currently used in hydroponic forcing. Five‐hundred and twenty RAPD primers (OPERON) were tested, of which 156 resulted in reproducible patterns and 26 yielded polymorphisms. Two‐hundred and fifty‐six AFLP primer‐combinations were tested and six combinations were selected for identification purposes. Similarity indices were measured and clustering has been done using pairwise comparison. Both types of marker provide similar conclusions. Two major clusters are formed, representing late and early cultivars. All cultivars were identified using 10 informative RAPD primers or three AFLP primer combinations. A low degree of polymorphism was detected between some early cultivars, suggesting a narrow genetic base in their breeding strategy.     

Construction of a genetic linkage map for witloof (Cichorium intybus L. var. foliosum Hegi)

A genetic linkage map based on an intraspecific cross between two inbred lines of witloof‐chicory (Cichorium intybus L. var. foliosum Hegi) has been constructed. In total, 129 RAPD markers were scored in 565 F₂ plants. Grouping of these markers at a LOD of threshold 4.0 resulted in nine linkage groups, which is equal to the chicory haploid genome. The nine linkage groups covered 609.6 cM. All 129 RAPD markers were linked to one of the nine groups. Three RAPD markers could not be mapped. Out of the 126 remaining RAPD markers, 18 showed segregation distortion with significance value of P < 0.01.     

QTL analysis of important pith characteristics in a cross between two inbred lines of chicory (Cichorium intybus var. foliosum): a preliminary study

The genetic basis of pith characteristics in chicory (Cichorium intybus L. var. foliosum Hegi) was investigated. Quantitative trait loci (QTL) were mapped in an F2 population (565 F2 plants) derived from a cross between two inbred chicory lines. A molecular marker linkage map of this cross had previously been constructed based on 129 random amplified polymorphic DNA markers. Each F2 plant was selfed and plant characteristics were measured in the F3 populations. Although variation in pith characteristics was largely environmentally influenced, QTL for the characteristics length of pith, browning of the pith, hollow pith and apple pith were detected in many linkage groups. Interactions between QTL were found for the three characteristics: pith length, browning of the pith and hollow pith. The QTL detected confirmed the early forcing suitability of the one parent inbred line and late forcing suitability of the other.