Integration of the soybean molecular and classical genetic linkage groups

To initiate the process of map integration, we used data from a Glycine max × G. max mapping population that had segregating markers at seven pigmentation (DI D2 G I L1 T Y9), six morphological (Dt1 E2 Lf1 Ln P1 Pd1), and seven isozyme (Aco4 Enp Idh1 Mdh Mpi Pgi Pgm1) loci (underscoring indicates marker members of the classical map). The parents of this population were two multi-marker strains, one a near-isogenic line (NIL) of the cultivar Clark, and the other a NIL of the cultivar Harosoy. Sixty F2.3 progeny lines were characterized for allelic status at the 20 classical loci, 8 RAPD loci, and 110 RFLP loci; the latter previously mapped in the G. max× G. soja mapping population. The computer program JoinMap was used to pool the linkage data obtained in both populations and to build consensus linkage groups. As a result of theses analyses, marker T of classical linkage group 1 (CLG-1) was assigned to molecular linkage group c2 (MLG-C2), marker P1 of CLG-2 to MLG-k, markers Dt1 and L1 of CLG-5 to MLG-l, marker Y9 of CLG-14 to MLG-e, and marker Mpi of CLG-18 to MLG-g. Probes A702 and B219, which hab detected two MLG-b1 markers (i.e., A702-1 and B219-1) in the G. max × G. soja population, detected two different (homoeologous?) markers (i.e., A702-2 and B219-4) in the Clark × Harosoy population, and these were linked to markers G, D1, and Pd1 of CLG-3. Markers Ln and Enp of CLG-4 were linked to two RFLP markers, but the MLG association was ambiguous because in the G. max × G. soja map one ot he RFLP markers mapped to MLG-f and the other mapped to MLG-i. With the CLG to MLG assignments made in this study, plus others that can be inferred from the recent literature, about half of the 19 soybean CLGs can now be associated with a corresponding MLG.