Abstract Interspecific hybrids were produced by crosses between the inbred lines of B. campestris and B. albogla- bra, and were backcrossed twice to B. campestris. Genet- ical constitutions of the BC 2 plants were analyzed by RAPD (random amplified polymorphic DNA), flow cy- tometry and cytological observations. By using 140 arbi- trary primers, a total of 137 polymorphic bands were ob- tained and 125 were found to be specific to B. albogla- bra. Based on the presence and absence of the specific RAPD markers of B. alboglabra, 13 synteny groups were constructed. The number of markers in each synteny group was found to be different and varied from 2 to 28. This reflects the difference in the degree of genetic vari- ability among the B. alboglabra chromosomes from those of B. campestris. Losses or gains of RAPD markers were observed frequently in most of the synteny groups, which indicated the occurrence of chromosome translocations and/or deletions in the chromosomes of B. alboglabra. In a population of 40 BC 2 plants, chromosome transmission rates were analyzed by using the RAPD markers in each synteny group. Most of the chromosomes of the synteny groups were transmitted with rates of 0.37–0.68. An ex- tremely high transmission rate, 0.98, was however ob- served in one of the synteny groups. Inheritance data of the synteny groups revealed relationships among them- selves. The plants lacking the RAPD markers of two syn- teny groups tended to lose others belonging to the rest of the synteny groups, indicating the effects of these groups on the transmission of B. alboglabra chromosomes to the B. campestris background. Key words Brassica campestris · Brassica alboglabra · Chromosome addition · RAPD markers · Intergenomic recombination Introduction The genus Brassica has abundant variations among and within its species, which are widely cultivated through- out the world. This genus is composed of three diploid species, B. campestris L. (AA, 2n=20), B. oleracea L. (CC, 2n=18), and B. nigra (L.) Koch (BB, 2n=16), and three amphidiploids, B. napus L. (AACC, 2n=38), B. juncea (L.) Czern. (AABB, 2n=36) and B. carinata Braun (BBCC, 2n=34). The amphidiploid species origi- nated from the hybridization between pairs of the three diploid species (U 1935). Cytological analyses, such as chromosome pairing and chiasma formation, in haploid plants revealed that the diploid species had diverged from a common ancestor (Röbbelen 1960; Armstrong and Keller 1981; Attia and Röbbelen 1986a, b), which suggests the possibility of the occurrence of chromosom- al recombination in the hybrids between the Brassica species. Attempts at the identification of Brassica chromo- somes have been made in recent years (Wang et al. 1989; Nishibayashi 1992; Olin-Fatih and Heneen 1992; Fukui et al. 1998). Each chromosome was characterized and classified based on its morphology and its banding pat- tern. Nevertheless, cytogenetic analysis of each of the discriminated chromosomes is still difficult because of limited information on each of the chromosomes and the technical difficulties encountered by the smallness of their size. Genetic markers are one of the most-effective meth- ods for chromosome analysis. Isozymes and RFLP mark- ers were effectively used for the identification of the chromosome addition lines of B. campestris-oleracea (Quiros et al. 1987; McGrath and Quiros 1990; McGrath et al. 1990; Hu and Quiros 1991) and B. napus-nigra (Chèvre et al. 1991). Chen et al. (1990) examined the in- Communicated by V. Glimelius T. Nozaki, K. Mishiba, M. Mii, T. Koba ( ✉ ) Faculty of Horticulture, Chiba University, Matsudo, Chiba 271-8510, Japan Present address: T. Nozaki, Nozaki Seed LTD., 1-1003 Daitoro, Nakagawa, Nagoya, 454-0943, Japan Theor Appl Genet (2000) 101:538–546 © Springer-Verlag 2000 ORIGINAL ARTICLE T. Nozaki · K. Mishiba · M. Mii · T. Koba Construction of synteny groups of Brassica alboglabra by RAPD markers and detection of chromosome aberrations and distorted transmission under the genetic background of B. campestris Received: 26 February 1999 / Accepted: 30 December 1999