|Mahama, A - IOWA STATE UNIVERSITY|
|Deaderick, L - ST. JOHNS EPISCOPAL CHRCH|
|Sadanaga, K - RETIRED|
|Newhousse, K - RETIRED|
Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 1999
Publication Date: N/A
Interpretive Summary: Chromosomes are threadlike structures that carry the genetic material of all plants and animals. Different types of plants/crops have different numbers of these threadlike structures. Soybean has twenty pairs of such threads. The threads can break and the broken pieces rejoin, or the broken piece from one thread can join to the broken end of a different thread. When two different threads break and exchange their end pieces, the produc is termed a reciprocal translocation. Seven translocations were mated to each other and also to soybean plants that did not have exchanged threadlike structures. The male reproductive cells (sperms/pollen), female reproductive cells (eggs/ovules) and the threadlike structures of their offspring (called F1 plants) were studied using the light microscope. About half of the sperms and half of the eggs died while the other half survived. The threadlike structures joined together to form rings. A comparison of the results from different F1 plants showed that one group o translocations (Clark T/T, KS172-11-3, and KS175-7-3) had a common broken piece of thread exchanged while a second group (PI 189866, KS171-31-2, and L75-0283-4) had a different common broken piece exchanged. In all six of the 20 threadlike structures were involved in the exchanges. These basic findings are useful to scientists in studies to learn the genetic control of reproduction. Consumers will benefit from new and improved products from soybeans.
Technical Abstract: A complete tester set of translocations would be useful in the advancement of classical and molecular genetic linkage maps in soybean. Seven translocation lines have been identified in soybean. Establishment of the independence of these seven translocation lines is a necessary step toward isolation of other independent translocations. This study confirmed cytologically that the seven lines are true chromosome translocations. Fourteen F1 progeny from intercrosses of six of the seven translocation lines, were analyzed cytologically. Results suggested that six of the twenty chromosomes are involved in reciprocal translocations in the six lines analyzed. The translocations Clark T/T, KS172-11-3, and KS175-7-3 share one chromosome in common, while PI 189866, KS171-31-2, and L75-0283-4 share a different chromosome in common. Percentage pollen abortion, ovule abortion, and reduction in seed set were higher in F1 progeny from crosses among homozygous translocation lines (a greater number of interchanged chromosomes) than from crosses between homozygous translocation lines and normal chromosome lines (only two nonhomologous chromosomes translocated). In terms of pollen and ovule abortion, and cytological behavior, soybean translocations were similar to those reported for many other crop species.