| Abstract
| - Genetic studies of a new male-sterile, female-sterile soybean (Glycine max (L.) Merr.) mutant showed that sterility is controlled by a single recessive gene nonallelic to any of the previously identified synaptic mutants, st2, st3, or st4 It was assigned gene symbol st5 The heterozygous form (T272H) has been added to the Soybean Genetic Type Collection. Linkage tests showed that the st5 gene was not linked to T(tawny pubescence) but was linked to w1 (white flower) with about 26.7 percent recombination. Additional tests indicated that st5 was not linked to the breakpoint of a homozygous chromosome translocation from PI 101,404B. Thus, the probable arrangement for linkage group 8 is: breakpoint of the translocation—ms1—w1—wm—st5. Cytological evidence showed that sterility was caused by desynapsis, failure of homologous chromosomes to remain paired throughout prophase I. Pairing of homologous chromosomes was fairly complete at pachytene in this desynaptic mutant, but almost totally absent at diakinesis and metaphase I. The st5 mutant is not suitable as a source of aneuploids because of its extremely low seed production.
|
