title: Genetic analysis of 4 new mutants at the unstable k2 Mdh1-n y20 chromosomal region in soybean.
abstract: In soybean (Glycine max (L.) Merr.), a chromosomal region defined by 3 closely linked loci, k2 (tan-saddle seed coat), Mdh1-n (malate dehydrogenase 1 null), and y20 (yellow foliage), is highly mutable. A total of 31 mutants have been reported from this region. In this study, a mutation with tan-saddle seed coat was found from bulk-harvested seed of cultivar Kenwood. Genetic analysis established that this tan-saddle seed coat mutation is allelic to the k2 locus and inherited as a recessive gene. Simple sequence repeat analysis showed that this mutant is not a contaminant from other existing k2 mutants. The mutant was named Kenwood-k2. To test for genetic instability at the k2 Mdh1-n y20 chromosomal region, Kenwood-k2 was crossed reciprocally with cultivars Harosoy and Williams. No new mutants were found in F2 families. In the genetic instability tests of T239 (k2) with cultivar Williams, 3 new mutants with yellow foliage (y20) and malate dehydrogenase 1 null (Mdh1-n) were identified. In the genetic instability tests of T261 (k2 Mdh1-n) with cultivar Williams, no new mutants were found. The Kenwood-k2 and the 3 yellow-foliage, malate dehydrogenase 1-null mutants provide additional genetic materials to study chromosomal aberrations in this mutable/unstable chromosomal region.
authors.affiliation: Department of Agronomy and Interdepartmental Genetics Graduate Program, Iowa State University, Ames, IA 50011, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Reid G
authors.initials: RG
authors.lastname: Palmer
mesh_terms: D000483:Alleles; D043171:Chromosomal Instability; D003433:Crosses, Genetic; D009154:Mutation; D012639:Seeds / Q000235:genetics; D013025:Glycine max / Q000235:genetics*