MOLECULAR AND MORPHOLOGICAL CHARACTERIZATION OF MONOSOMIC ADDITIONS IN BETA-VULGARIS, CARRYING EXTRA CHROMOSOMES OF BETA-PROCUMBENS OR B-PATELLARIS

DNA fingerprinting with three repetitive DNA sequences (OPX2, PB6-4 an d Sat-121) was carried out on a set of IO monosomic additions of Beta procumbens and 75 anonymous B. patellaris-derived monosomic additions in B. vulgaris, for characterization of the alien chromosomes at the D NA level. The probes are Procumbentes-specific and distributed over al l chromosomes. Morphological characteristics were also used for the cl assification of B. patellaris monosomic addition families and for comp arison with the morphology of the addition families of B. procumbens. DNA fingerprinting revealed unique patterns for almost all individual addition chromosomes of B. procumbens. However, it was concluded that chromosomes 1 and 6 of B. procumbens may be identical with the only di fference that the chromosome referred to as 6 carries a susceptible al lele for beet cyst nematode (BCN) resistance. In contrast, it was conc luded that the two addition types with chromosome 2 are carrying diffe rent chromosomes of B. procumbens, so that one of them was renumbered to become the new chromosome 6. DNA fingerprinting of 75 anonymous B. patellaris-derived monosomic additions facilitated the identification and characterization of the alien chromosomes and the grouping of thes e additions into nine different groups. Several of these groups could be divided in two sub-groups on the basis of small differences in band ing patterns. The results of the DNA fingerprinting led to the conclus ion that B. patellaris most likely is an allotetraploid. It was also d educed that the BCN gene(s) in this species are homozygous and located on chromosome 1, while the pair of homoeologous chromosomes does not carry such BCN gene(s). Because of the allotetraploid nature of B. pat ellaris, preferential association occurs between the two homologous ch romosomes containing the allele(s) for BCN resistance. Each group of B . patellaris addition families united by DNA fingerprinting had compar able morphological characteristics. Some of these morphological traits appeared to be chromosome-specific and were very useful for primary c lassification of the addition families. However, the present study sho wed that these morphological traits are not adequate for the identific ation of all alien chromosomes without the aid of additional markers. Because of similarities observed between molecular characteristics or the effects on plant morphology of several chromosomes of B. procumben s and B. patellaris it was concluded that B. procumbens could have bee n involved in the evolutionary history of B. patellaris.