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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #138865
Title: GENETIC LINKAGE IN SOYBEAN: CLASSICAL GENETIC LINKAGE GROUPS 6 AND 8, AND TRANSLOCATION BREAKPOINTS

Author
item MAHAMA, ANTHONY - ISU
item PALMER, REID

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2003
Publication Date: 8/18/2003
Citation: MAHAMA, A.A., PALMER, R.G. GENETIC LINKAGE IN SOYBEAN: CLASSICAL GENETIC LINKAGE GROUPS 6 AND 8, AND TRANSLOCATION BREAKPOINTS. CROP SCIENCE. 2003. v. 43. p. 1602-1609.

Interpretive Summary: Knowledge of the location of traits (genes) along the units of hereditary (chromosomes) and the distance between the traits is important in plant breeding and genetics. Sometimes breaks (spontaneous, chemically induced, irradiation induced) occur in the chromosomes. When two breaks occur in different chromosomes and different chromosomes join together, the affected chromosomes are said to be interchanged or translocated. Chromosome translocations are powerful tools in mapping traits to chromosome segments. Three different chromosome translocations were used in mapping traits. Interestingly, all three showed that one of the chromosome breaks was between the same two genetic traits. The significance is not known but it means that this chromosome region has a higher than average probability to break. Chromosome translocations can cause partial male and female sterility. This characteristic is useful to locate traits on the chromosome but detrimental for the farmer. Plant breeders will use the research to practice selection against translocations.

Technical Abstract: Reciprocal chromosome translocations are important for locating genes to linkage groups (LGs). Identifying the chromosomes involved in translocations is necessary for the isolation of tester sets. Our objectives were 1) to determine the location of translocation breakpoints by testing linkage with loci of CLG 6 (Df2 and Y11), CLG 8 (Adh1, Ms1, Ms6, St5, W1, and Y23,), and other CLGs, and 2) to confirm the orientation of marker loci of CLGs 6 and 8. The 'KS172-11-3', 'KS175-7-3', 'Clark T/T', 'KS171-31-2', 'PI 189866', and 'L75-0283-4' soybean with homozygous chromosome translocations were crossed to the same genetic marker types. F2 seed was increased at the University of Puerto Rico/Iowa State University soybean nursery, near Isabela, PR. Data for the different characters used as marker traits were collected from F2 populations and F2:3 families. Recombination values revealed linkage between the breakpoints in KS172-11-3, KS175-7-3, and Clark T/T, and Df2, Y11, and several loci of CLG 8. Interestingly, these three translocations had a common breakpoint between Y11 and Ms1, but no linkage was identified between these loci and the breakpoints in KS171-31-2, PI 189866, and L75-0283-4. Our data further showed that CLGs 6 and 8 are the same LG, with Df2 and Adh1 at the ends of the chromosome segment. KS172-11-3, KS175-7-3, and Clark T/T share a common translocated chromosome which is different from that in KS171-31-2, PI 189866, and L75-0283-4. This information will facilitate the assignment of CLGs and the isolation of a tester set of translocations, and enhance genetic linkage mapping.