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Reference Report for IND20599817
Title:Evidence for homoeologous linkage groups in the soybean.
Authors:Lohnes, D.G., Specht, J.E., Cregan, P.B.
Source:Crop Sci. 1997, 37(1):254-257
Abstract:Substantial progress towards the integration of the soybean (Glycine mar (L.) Merr.) classical and molecular marker linkage maps recently was achieved by using a 60-plant F2 population derived from a mating of isolines of the cultivars Clark and Harosoy. However, epistasis limited the completeness of F2 genotyping at two independently segregating loci, D1 and D2, which produced yellow (Y) and green (G) cotyledons in a duplicate recessive fashion (i.e., only the d1d1d2d2 F2 genotype was green). F2 genotypic assignments were obvious for two of the four F2.3 phenotypes (15Y:IG from 1d1D2d2 and all G from d1d1d2d2), but were equivocal for the other two (all Y from D1D1D2D2, D1D1D2d2, D1d1D2D2, D1D1d2d2, or d1d1D2D2; 3Y:IG from D1d1d2d2 or d1d1D2d2). Here, we propose an inferential means of near complete F2 genotyping, by using F2.3 data collected on locus G, which produces G (GG and Gg) and Y (gg) seed coats. Locus G is tightly linked (4.2%) to the D1 locus. Given the repulsion-phase parental gametes of Gd1 and gD1, we inferred, with a low probability of (recombinational) error, that the GG, Gg, or gg F2 genotypes must be d1d1, D1d1, or D1D1, respectively. Genetically, a F2 plant with all Y or 3Y:lG F2.3 progeny and an inferred GGd1d1 genotype must also be D2D2 or D2d2, respectively, and an inferred GgD1d1 genotype must also be D2D2 or d2d2, respectively. The alleles at D2 could not be inferred from the ggD1D1 genotype. The updated 60-plant marker data, when subjected to a Mapmaker linkage analysis, revealed that D1 mapped (as expected) to linkage group (LG) 1 and D2 mapped to LG 10 of the Clark times Harosoy map. Duplicate genes and homologous linkage groups support the hypothesis that the diploid soybean is derived from a tetraploid.






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