M. Mesbah et al., MOLECULAR AND MORPHOLOGICAL CHARACTERIZATION OF MONOSOMIC ADDITIONS IN BETA-VULGARIS, CARRYING EXTRA CHROMOSOMES OF BETA-PROCUMBENS OR B-PATELLARIS, Molecular breeding, 3(2), 1997, pp. 147-157
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.