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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #186208
Title: GENETIC ANALYSIS OF FOUR NEW MUTANTS AT THE UNSTABLE K2 MDH1-NY20 CHROMOSOMAL REGION IN SOYBEAN

Author
item XU, MIN - ISU
item Palmer, Reid

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2006
Publication Date: 7/12/2006
Citation: Xu, M., Palmer, R.G. 2006. Genetic analysis of four new mutants at the unstable k2 Mdh1-ny20 chromosomal region in soybean. Journal of Heredity. 97:423-427.

Interpretive Summary: Instability in plants can be seen as variegation in leaves, flowers, seeds, etc. This instability can be the result of insects, diseases, viruses, etc. Genetic instability or mutability was noticed in soybean seed of cultivar Kenwood. The normal yellow seed showed a tan saddle pattern. This tan saddle change (mutation) was the same genetics as previously described tan saddle mutants. These known mutants, in certain genetic combinations (cross-pollinations), generate new mutations, usually at a certain genetic location. This new tan-saddle mutant and two previously described tan saddle mutants (T239 and T261) were cross-pollinated to a widely-grown soybean cultivar. The Kenwood and T261 tan-saddle mutants failed to elicit instability (mutability) in the cross-pollinations. However, T239 elicited mutability and three new yellow plants missing an enzyme were identified. Genetic evaluation showed that these three mutants were genetically located at the same area as previous mutants. These new mutations provide additional genetic materials to study mutability (instability) in soybean. Researchers who study genome organization and evolution will find these mutants useful because instability is a method to generate changes in genome structure.

Technical Abstract: In soybean [Glycine max (L.) Merr.], a chromosomal region defined by three closely linked loci, k2 (tan-saddle seed coat), Mdh1-n (malate dehydrogenase 1 null), and y20 (yellow foliage), is very unstable. 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. Genetics analysis established that this mutation is allelic to the k2 locus, and inherited as a recessive gene. The mutant was named Kenwood-k2. SSR (simple sequence repeat) analysis showed that Kenwood-k2 is not a contamination from other existing k2 mutants. To test for genetic instability at the k2 Mdh1-n y20 chromosomal region, Kenwood-k2 was crossed reciprocally with cultivars Harosoy and Williams. No mutants were found in F2 families. In the instability tests of T239 (k2) and T261 (k2 Mdh1-n), three new mutants with yellow foliage (y20) and malate dehydrogenase 1 null (Mdh1-n) were identified in crosses of T239 with cv. Williams, but no mutants were found in crosses of T261 with cv. Williams. The new mutants provide additional genetic materials to study chromosomal aberrations in this unstable chromosomal region.