Monosomic addition lines of Beta corolliflora Zoss in sugar beet: cytological and molecular-marker analysis

Beta corolliflora is a wild relative of sugar beet (Beta vulgaris) with 2n= 4x=36 chromosomes. Monosomic addition lines (2n=19) of B. corolliflora in B . vulgaris were identified from backcross progenies between triploid hybrid s (genome constitution VVC) and sugar beet. They were characterized by DNA- fingerprinting using nine different B. corolliflora-specific repetitive seq uences as probes and by fluorescence in situ hybridization (FISH) using two B. corollifora specific sequences and two rDNA probes. Unique banding patt erns obtained after genomic Southern hybridization enabled the classificati on of monosomic addition lines into 11 clusters, three of which proved to h ave a wild beet chromosome fragment in addition to the sugar beet chromosom es as revealed by FISH. Repetitive sequences pBC216 and pBC1416 were found to be present only on wild beet chromosomes IV and V. Chromosomes I and IV were found to carry genes for 18S and 5S rRNA, respectively. An idiogram of B. corolliflora was established in the triploid VVC hybrid on the basis of chromosome size and FISH. Eight B. corolliflora addition lines could be un equivocally identified by Southern hybridization and FISH, one addition lin e carrying the missing wild beet chromosome is probably not viable under gr eenhouse conditions. The monosomic addition lines will serve as a bridge fo r transferring genes from wild species to sugar beet and will help to uncov er genetic relationships between species of the genus Beta.