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Crop Science Abstract -

RFLP Analysis of Soybean Breeding Populations: I. Genetic Structure Differences due to Inbreeding Methods


This article in CS

  1. Vol. 34 No. 1, p. 55-61
    Received: Apr 9, 1993

    * Corresponding author(s):
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  1. P. Keim ,
  2. W. D. Beavis,
  3. J. M. Schupp,
  4. B. M. Baltazar,
  5. B. M. Mansur,
  6. R. E. Freestone,
  7. M. Vahedian and
  8. D. M. Webb
  1. Dep. of Biology, Northern Arizona Univ., Flagstaff, AZ 86011-5640
    Dep. of Data Management, Pioneer Hi-Bred International, 7250 N.W. 62nd Ave, Johnston, IA 50131-1004
    Dep. of Research Specialists, Pioneer Hi-Bred International, 7250 N.W. 62nd Ave, Johnston, IA 50131-1004
    Dep. of Biology, Univ. of Utah, Salt Lake City, UT 84012
    Soybean Breeding Dep., Pioneer Hi-Bred International, Inc., 3261 West Airline Highway, Waterloo, IA 50703



Segregating soybean [Glycine max (L.) Merr.] breeding populations are frequently inbred by either single-seed descent or by bulking progeny at each generation. During inbreeding, repetitive sampling of individual genotypes, or natural selection, may decrease the potential for genetic gain in a population. This is most likely to occur in populations that are inbred by the bulk method. This study examines the genetic structure of two soybean populations, each containing 261 segregating lines. One population was derived from a cross of two elite lines and was inbred by a multiple-seed descent (MSD) strategy that is frequently employed by soybean breeders. A second population was derived from an elite × unadapted genotype cross that was inbred by single-seed descent (SSD). The genetic composition of each line and the genetic distances among lines were estimated using 100 RFLP markers. The genetic contribution of each parent to each population was equivalent regardless of the inbreeding procedure. No individual in either population obtained greater than 75% of its genes from a particular parent. Close genetic relationships among lines were not observed in the SSD population, but were common in the MSD population. Cluster analysis of individual lines within the MSD population indicated that about 18% of the lines were due to repetitive sampling and, therefore, did not represent independent lineages. The repetitive sampling appeared to be caused by stochastic processes, as opposed to systematic factors such as differential fecundity among genotypes. Genetic marker analysis of population structure provides a method for directly assessing the effectiveness of inbreeding strategies.

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