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Crop Science Abstract - Crop Breeding & Genetics

Comparison of Phenotypic Methods and Yield Contributions of Quantitative Trait Loci for Partial Resistance to Phytophthora sojae in Soybean


This article in CS

  1. Vol. 52 No. 2, p. 609-622
    Received: June 25, 2011

    * Corresponding author(s): dorrance.1@osu.edu
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  1. Hehe Wanga,
  2. Steven K. St. Martinb and
  3. Anne E. Dorrance *a
  1. a The Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
    b The Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH 43210


In several host–pathogen systems, the detection of an individual quantitative trait locus (QTL) differed depending on the specific pathogen isolate or phenotypic assay that was used. Moreover, the contribution of a QTL toward yield is an important factor for selecting specific QTL candidates for resistance breeding. The first experiment in this study compared the QTL identified previously in a ‘Conrad’ × ‘Sloan’ F4:6 soybean [Glycine max (L.) Merr.] population challenged with Phytophthora sojae Kaufmann and Gerdemann isolate 1.S.1.1 to the QTL identified when this same population was challenged with isolates PT2004C2.S1 and OH25 using a tray test assay. In the second experiment, QTL were mapped in the same population with P. sojae isolate 1.S.1.1 using a different phenotypic assay, the layer test. In the third experiment, the impact of these QTL on soybean yield was evaluated using 20 selected recombinant inbred lines (RILs) grown in a field infested with P. sojae. Resistance QTL with smaller effects, especially those from the susceptible parent, were not consistently detected with the three isolates or the two phenotypic assays. Composite interval mapping identified a major Conrad QTL on chromosome 18 and one on 19 that were detected with all three isolates and both phenotypic assays. Recombinant inbred lines with resistance alleles at these QTL had significantly higher yields (∼1000 kg ha−1 more) than RILs with susceptible alleles. These results indicate the important role these QTL play in conferring partial resistance to P. sojae.

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