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This article in CS

  1. Vol. 48 No. 2, p. 471-479
     
    Received: June 29, 2007


    * Corresponding author(s): phil.bregitzer@ars.usda.gov
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doi:10.2135/cropsci2007.06.0370

A Single Backcross Effectively Eliminates Agronomic and Quality Alterations Caused by Somaclonal Variation in Transgenic Barley

  1. P. Bregitzer *a,
  2. Lynn S. Dahleenb,
  3. Stephen Neatec,
  4. Paul Schwarzd and
  5. Muthusamy Manoharane
  1. a USDA–ARS National Small Grains Germplasm Research Facility, 1691 S. 2700 W., Aberdeen, ID 83210
    b USDA–ARS, Northern Crop Science Lab., 1307 N. 18th St., Fargo, ND 58105
    c Dep. of Plant Pathology, Walster Hall, North Dakota State Univ., Fargo, ND 58105
    d Dep. of Plant Sciences, Loftsgard Hall, North Dakota State Univ., Fargo, ND 58105
    e Dep. of Agriculture, Univ. of Arkansas at Pine Bluff, AR 71601

Abstract

Transgenic crops have proven commercial utility but are created using processes known to produce undesirable variability known as somaclonal variation. This reduces the utility of transgenic germplasm to the plant breeder and complicates assessments of transgene-encoded phenotypes. Backcrossing transgenes into a wild-type genome is one solution, but producing near-isogenic lines requires a lengthy and resource-intensive process of multiple crosses. However, an abbreviated breeding scheme involving a single backcross to the wild-type parent used to produce a transgenic line, which would replace 75% of the variant alleles, should produce transgenic lines with improved performance. Comparisons were made of ‘Conlon’ barley (Hordeum vulgare L.), primary transgenic lines derived from Conlon, and lines derived from single backcrosses of primary transgenic lines to Conlon. The primary transgenic lines were different from Conlon for many agronomic and malting characteristics. Most of the backcross-derived lines did not differ significantly from Conlon for most agronomic characteristics. The backcross-derived lines were also similar to Conlon for malting quality traits but showed more differences than for agronomic characteristics. Differences between lines encoding TRI101 versus lines encoding PDR5 suggested that PDR5 insertion or expression may have affected malting quality. It is concluded that a single backcross is an effective, rapid, and inexpensive method for creating superior transgenic lines.

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