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Crop Science Abstract -

Resistance to Soybean Sudden Death Syndrome and Root Colonization by Fusarium solani f. sp. glycine in Near-Isogenic Lines


This article in CS

  1. Vol. 38 No. 2, p. 472-477
    Received: May 5, 1997

    * Corresponding author(s): GA4082@SIU.EDU
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  1. V. N. Njiti,
  2. T. W. Doubler,
  3. R. J. Suttner,
  4. L. E. Gray,
  5. P. T. Gibson and
  6. D. A. Lightfoot 
  1. Garst Inc., Zeneca Inc., 2369 330th St., Box 500, Slater, IA 50244
    Dep. of Plant and Soil Science, Molecular Science Program, Southern Illinois Univ., Carbondale, IL 62091
    USDA, ARS, Dep. of Crop Science, Univ. of Illinois, Urbana, IL 61801



One genomic region in soybean [Glycine max (L.) Merr.] ‘Essex’ and three in ‘Forrest’ underlie field resistance to sudden death syndrome (SDS) leaf scorch in their recombinant inbred line (RIL) progeny. Root infection by Fusarium solani (Mart.) Sacc. f. sp. glycine precedes the leaf scorch caused by SDS. Forrest shows rate-reducing resistance to both root colonization by F. solani and leaf scorch, whereas Essex does not. Our objective was to determine whether genomic regions that underlie resistance to the SDS leaf scorch also caused resistance to root colonization by F. solani in near-isogeneic lines (NILs). The NILs were derived from individual plants selected from within one recombinant-inbred line (ExF34). ExF34 was heterogenous within regions of linkage group C2 and G, each of which encompassed quantitative trait loci (QTL) for resistance to SDS. Using DNA markers, four genotypiclasses could be identified. The QTL effects were compared with two SDS disease parameters, leaf scorch measured as SDS disease index (DX) at the R6 growth stage and root colonization by F. solani measured as infection severity (IS) the R5.5 and R8 growth stages. The Forrest allele of the genomic region on linkage group G was consistently associated with decreased DX (P < 0.05–0.0004) and IS (P < 0.05–0.0017). The Essex allele the genomic region on linkage group C2 caused a decrease in DX (P > 0.05) and IS in the susceptible pair of the four NIL clases R5.5 but not R8. Therefore, the QTL on linkage group G and C2 confer separate components of resistance to SDS that are suitable for selection in a resistance gene pyramid.

Product names are necessary to report factually on the available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.

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