Relationships among Cichorium species and related genera as determined by analysis of mitochondrial RFLPs

Species relationships in Lactuca s.l. (Lactuceae, Asteraceae) inferred from AFLP fingerprints

An AFLP data set comprising 95 accessions from 20 species of Lactuca s.l. (sensu lato) and related genera was generated using the primer combinations E35/M48 and E35/M49. In phenetic analyses of a data subset, clustering with UPGMA based on Jaccard's similarity coefficient resulted in the highest cophenetic correlation, and the results were comparable to those of a principal coordinates analysis. In analyses of the total data set, phenetic and cladistic analyses showed similar tree topologies for the well-supported parts of the trees. The validity of cladistic analysis of AFLP data is discussed. The results do not support a distinction among the serriola-like species L. sativa, L. serriola, L. dregeana, and L. altaica, which is in line with previous results. Therefore, we postulate that these species are conspecific. The serriola-like species L. aculeata occupies a clearly separate position, making it an ideal outgroup for studies of the closest relatives of L. sativa. The subsect. Lactuca as a group is well supported by our data, but the positions of L. saligna and L. virosa relative to the serriola-like species remain unclear. The close relationship between the sect. Mulgedium species L. tatarica and L. sibirica is corroborated by the present AFLP results and by additional crossability data.

A search for diagnostic AFLP markers in Cichorium species with emphasis on endive and chicory cultivar groups

The genus Cichorium consists of two widely cultivated species C. intybus (chicory) and C. endivia (endive) and four wild species, C. bottae, C. spinosum, C. calvum, and C. pumilum. A multivariate and an UPGMA (unweighted pair group method average) analysis based on AFLP (amplified fragment length polymorphism) markers were used to establish the genetic relationships among the species and cultivar groups of C. intybus and C. endivia. At the species level, the results correspond with previously obtained phylogenetic relationships in that C. bottae is the most divergent species, and C. intybus and C. spinosum, as well as C. endivia, C. pumilum, and C. calvum formed clusters. Based on the congruence between phylogenetic and genetic analyses, unique markers were expected for all species, however, hardly any specific marker was found except for C. bottae. The analysis of cultivar groups of C. intybus resembled the species analysis in two respects: (i) grouping of cultivars according to cultivar groups, and (ii) lack of markers unique to cultivar groups. In contrast to C. intybus, the cultivar series of C. endivia do not form distinct groups, which would reflect that crosses have been made among the various cultivar groups. The relationships among Cichorium species and cultivars will be useful for setting up a core collection of Cichorium, and stress the importance of inclusion of the wild species in the collection.

Phylogenetic relationships among Lactuca (Asteraceae) species and related genera based on ITS-1 DNA sequences

Internal transcribed spacer (ITS-1) sequences from 97 accessions representing 23 species of Lactuca and related genera were determined and used to evaluate species relationships of Lactuca sensu lato (s.l.). The ITS-1 phylogenies, calculated using PAUP and PHYLIP, correspond better to the classification of Feráková than to other classifications evaluated, although the inclusion of sect. Lactuca subsect. Cyanicae is not supported. Therefore, exclusion of subsect. Cyanicae from Lactuca sensu Feráková is proposed. The amended genus contains the entire gene pool (sensu Harlan and De Wet) of cultivated lettuce (Lactuca sativa). The position of the species in the amended classification corresponds to their position in the lettuce gene pool. In the ITS-1 phylogenies, a clade with L. sativa, L. serriola, L. dregeana, L. altaica, and L. aculeata represents the primary gene pool. L. virosa and L. saligna, branching off closest to this clade, encompass the secondary gene pool. L. virosa is possibly of hybrid origin. The primary and secondary gene pool species are classified in sect. Lactuca subsect. Lactuca. The species L. quercina, L. viminea, L. sibirica, and L. tatarica, branching off next, represent the tertiary gene pool. They are classified in Lactuca sect. Lactucopsis, sect. Phaenixopus, and sect. Mulgedium, respectively. L. perennis and L. tenerrima, classified in sect. Lactuca subsect. Cyanicae, form clades with species from related genera and are not part of the lettuce gene pool.

Cytoplasmic DNAs and nuclear rDNA restriction fragment length polymorphisms in commercial witloof chicories

Restriction fragment length polymorphisms of cytoplasmic DNAs and nuclear rDNA were analyzed in several Cichorium intybus genotypes, comprising four white inbred lines, eight red witloof experimental lines, and a number of F1 hybrids derived from two white parents. Chloroplast and mitochondrial restriction patterns led to the distinction between two different cytoplasms, called I and II. Southern hybridization using a nuclear rDNA probe revealed that all the lines possessed two types of rDNA repeat units. The shortest unit was 10 kb and was common to all lines. The largest rDNA repeat unit was 10.5 kb in lines I and 10.4 kb in lines II. In addition, a sequence heterogeneity between the 10.5 and 10.4-kb rDNA repeat units was revealed by Sac I digestion. A 10-kb rDNA unit was successively cloned, mapped, and used as a probe to check the genetic purity of F1 hybrid seeds between line I and II white parents. We found a 30% average percentage of impurities, originating both from selfing and full-sib crossing, in different open-pollinated hybrid samples.