Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 37pg1
LINKAGE GROUP COMPARISON FOR THE A, B, AND C GENOMES OF THE
GENUS BRASSICA
M.J. Truco and C.F. Quiros. Department of Vegetable Crops.
University of California. Davis, CA 95616.
In order to study the evolution of Brassica genomes, we
compared linkage maps of the three diploid species in this genus:
B. rapa (A genome), B. nigra (B genome) and B. oleracea (C
genome). The linkage maps were generated from F2 segregating
populations using the same set of probes (random and known
sequences from a cDNA library of B. napus, SI gene from B.
oleracea and seed storage protein genes). Some isozymes were
also included. Only 40% of the probes were segregating in all
three populations, the rest were polymorphic only in two of the
populations simultaneously. It was possible to find conserved
regions between each pair of linkage maps, but in general there
was a lot of reordering among the genomes. There were more
conserved regions between B. rapa and B. oleracea linkage maps
than between any of these two species and B. nigra linkage map.
This finding agrees with other reports suggesting a closer
phylogenetic relationship between B. rapa and B. oleracea than
between these species and B. nigra.
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