Pb. Cregan et al., Primary trisomics and SSR markers as tools to associate chromosomes with linkage groups in soybean, CROP SCI, 41(4), 2001, pp. 1262-1267
Primary trisomics provide an excellent cytogenetic tool to associate genes
and linkage groups with their respective chromosomes. A complete set of 20
primary trisomics (2x + 1 = 41) has been established in soybean [Glycine ma
x (L.) Merr.]. A linkage map of soybean with 20 consensus linkage groups ha
s recently been defined. Because simple sequence repeat (SSR) markers map t
o defined single positions in the soybean genome, the association of a SSR
locus with a chromosome will provide an unambiguous association of a linkag
e group to a specific chromosome. The objective of this work was to demonst
rate the use of SSR markers to associate linkage groups with chromosomes by
means of primary trisomics. One population of F-2 plants was developed fro
m an F-1 hybrid trisomic for chromosome 13 (Triplo 13) and a second F-2 pop
ulation was obtained from a F-1 hybrid trisomic for chromosome 5 (Triplo 5)
. Polymorphic SSR markers from different consensus linkage groups were test
ed on a subset of 20 plants from each population to identify markers that a
ppeared to show segregation that deviated from normal (1:2:1) disomic inher
itance. Markers not associated with the specific chromosome segregated in a
disomic (1:2:1) fashion. Markers identified in this manner were further ex
amined in the complete population of F-2 plants to identify those that demo
nstrated trisomic segregation (6:11:1). By this approach, Triplo 13 was ass
ociated with linkage group F and Triplo 5 with linkage group A1. This resul
t was verified by the examination of seven SSR loci on linkage group F and
eight loci from linkage group A1 with each showing trisomic segregation wit
h the Triplo 13- and Triplo 5-derived F-2 populations, respectively. These
results demonstrate the first association of molecular linkage groups with
chromosomes in soybean and indicate that SSR markers provide a tool to asso
ciate the remaining 18 trisomics with their respective linkage groups.