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United States Department of Agriculture

Agricultural Research Service


item Williams, Claire
item Goodman, Major
item Stuber, Charles

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: As a part of the reproductive process in most plants, genetic factors are reshuffled through a process called recombination. This is a process that generates new variability and is very important in corn (Zea mays L.) breeding programs. When wide crosses are made between U.S. corn and Latin American strains or between U.S. corn and relatives of corn (such as teosinte) recombination may be affected. This paper reports the first comparative survey of recombination in New World corn and involved 16 widely diverse populations. In some cases, recombination was enhanced, and in others it was restricted. These results are important for corn breeders who wish to utilize exotic corn populations to increase genetic diversity in their breeding programs.

Technical Abstract: Recombination distances and linkage heterogeneity were compared among a wide range of maize inbreds, wide crosses and maize x teosinte hybrids. Twelve maize and four teosinte races were backcrossed to stocks fixed for rare marker alleles on chromosome arm 1L. Estimates for recombination were higher for exotic germplasm than for either U.S. maize or maize x teosinte crosses. Serrano, Tuxpeno and a US-adapted inbred line of tropical origin, NC300, exhibited enhanced recombination distances. Three of the four maize x teosinte hybrids had little or no recombination between two loci. The observed recombination "shrinkage" resulted from an apparent inversion in the vicinity of the Amp1 locus. Distorted segregation ratios did not unduly bias recombination estimates. Average recombination distances among common marker loci for composite maps were highly variable, even when map construction was restricted to maize germplasm of similar origins. Alternatives to map-based cloning are needed for large, complex genomes such as maize.

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