PRODUCTION AND CYTOGENETICS OF BRASSICA-CAMPESTRIS-ALBOGLABRA CHROMOSOME ADDITION LINES

Four different Brassica campestris-alboglabra monosomic addition lines (AA + 1 chromosome from C, 2n = 21) were obtained after consecutive b ackcrosses between resynthesized B. napus (AACC, 2n = 38) and the pare ntal B. campestris (AA, 2n = 20) accession. The alien chromosomes of B . alboglabra (CC, 2n = 18) in the addition lines were distinguished by random amplified polymorphic DNA (RAPD) marker analysis and morpholog y of mitotic chromosomes. Four RAPD marker synteny groups were establi shed, which represented the four different alien chromosomes of B. alb oglabra in the four addition lines. Three of the four addition lines w ere identified to harbour chromosomes 4, 8 or 9 of B. alboglabra. Stud ies on meiotic pairing in the addition lines revealed intergenomic hom eology relationships among specific chromosome arms between the A- and C-genomes. The long arm of B. campestris chromosome 9 was homoeologou s with the long arm of B. alboglabra chromosome 4, while its short arm with the short arms of B. alboglabra chromosomes 8 and 9. Such an int ergenomic homoeology relationship supports the hypothesis that B. camp estris and B. alboglabra share a common ancestor but that chromosomal rearrangements have occurred during the evolution of the two species. Intergenomic introgression was observed in the progenies of the additi on lines. The introgression of an entire B. alboglabra marker synteny group into the B. campestris genome implied the possible occurrence of interspecific chromosomal substitution.