GENERATION AND CHARACTERIZATION OF MONOSOMIC CHROMOSOME ADDITION LINES OF BRASSICA-CAMPESTRIS BRASSICA-OXYRRHINA

Monosomic chromosome addition lines of Brassica oxyrrhina in the backg round of alloplasmic B. campestris carrying B. oxyrrhina cytoplasm wer e generated and characterised through morphology, cytology and molecul ar (RAPD) analysis. Four successive backcrosses of the synthetic allop loid B. oxycamp with B. campestris yielded 24 monosomic addition plant s that were grouped into seven different synteny groups based on morph ological similarity and RAPD patterns. Each synteny group exhibited mo rphological features diagnostic for the presence of individual B, oxyr rhina chromosomes including some novel phenotypes. Meiotic studies of the addition lines revealed the homoeology of four B. oxyrrhina chromo somes (synteny groups 1, 3, 5 and 6) with B. campestris chromosomes as indicated by trivalent associations, with the highest homoeology (44. 23%) in synteny group 1 and the lowest (6.1%) in synteny group 3. Seed fertility of the addition lines ranged from 94.85% (synteny group 1) to 56.98% (synteny group 5). All of the addition lines were male-steri le except synteny group 6 which had 12-16% stainable pollen. Ovule tra nsmission of the B. oxyrrhina chromosomes added to the progenies of ad dition lines ranged from 23.52% (synteny group 6) to 14% (synteny grou p 7). RAPD analysis confirmed the validity of synteny grouping based o n morphological observations. Approximately 45% of the primers studied were informative, giving B. oxyrrhina-specific RAPD bands unique for each synteny group, except group 6.