RELATIONSHIPS OF WILD BRASSICA SPECIES WITH CHROMOSOME-NUMBER 2N = 18, BASED ON COMPARISON OF THE DNA-SEQUENCE OF THE CHLOROPLAST INTERGENIC REGION BETWEEN TRNL (UAA) AND TRNF (GAA)

A specific chloroplast DNA sequence was compared in 34 populations rep resenting 10 wild Brassica species (2n = 18). Species studied were Bra ssica bourgeaui (Webb) O. Kuntze, Brassica cretica Lam., Brassica hila rionis G.E. Post, Brassica incana Ten., Brassica insularis Moris, Bras sica macrocarpa Guss., Brassica montana Pourret, Brassica oleracea L., Brassica rupestris Raf., and Brassica villosa Biv. The sequence was l ocated between the trnL and trnF genes in the large, single-copy regio n of the chloroplast genome. Site-specific primers were used to amplif y the region via the polymerase chain reaction technique. Products of the same size were amplified from all populations. Sequence difference s in the DNA fragments were detected by denaturing gradient gel electr ophoresis. Ten different haplotypes defined by 20-base sequence differ ences were detected. Haplotype did not always reflect species classifi cation. Haplotypes were shared by the species pairs B. rupestris -B. v illosa, B. cretica -B. incana, and B. bourgeaui -B. oleracea. Populati ons carrying divergent haplotypes were discovered for B. cretica, B. m ontana, and B. insularis. Possible introgression of the B. macrocarpa cytoplasm into a B. insularis population was observed. DNA sequences f or the 10 haplotypes were determined and subjected to phylogenetic ana lysis using maximum parsimony. In the phylogenetic tree, the B. rupest ris -B. villosa haplotype formed a basal clade, the B. macrocarpa hapl otype diverged next, while all other species fell into a third clade.