Ideograms of the extant and ancestral genomes of clade E tribes and examples of cytogenetic analyses. A, Genome structure of C. tenella (CHOR). B, Genome structures of E. syriacum and the neotetraploid S. africana (both EUCL). Black arrows refer to the inverted collinearity of block E in relation to the ancestral crucifer karyotype (ACK); red arrows show a EUCL-specific paracentric inversion on chromosome 1; the blue arrow indicates a paracentric inversion differentiating chromosome 3 in E. syriacum and S. africana. C, Identification of genomic blocks A and B (linkage group 1) by comparative chromosome painting analysis on pachytene chromosomes (top three species) and mitotic chromosomes of seven clade E species. D, Ancestral karyotype of clade E (CEK). The color code and capital letters correspond to the eight chromosomes and 22 genomic blocks of ACK, respectively. The black circle marks the position of the 35S rDNA locus. Colors in C correspond to epifluorescence of biotin-, digoxigenin- and Cy3-labeled painting contigs. Chromosomes were counterstained by 4′,6-diamidino-2-phenylindole (DAPI).