Submitted to: Mid Atlantic Plant and Molecular Biology Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2001
Publication Date: N/A
The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is the foremost pest of soybean (Glycine max L. Merr.) and is responsible for the loss of 10% of the annual U.S. soybean crop. The most practical management strategy has been the use of resistant cultivars. The rhg1 resistance allele on Linkage Group G and the Rhg4 resistance allele on Linkage Group A2 of the soybean genetic map are especially important. Markers closely linked to the Rhg4 locus were used to screen a bacterial artificial chromosome (BAC) library of susceptible 'Williams 82' and identified a 150kb BAC. End-sequenced EcoR I subclones located to an Apa I restriction map provided landmarks used to identify the corresponding region in a BAC library of the soybean accession PI 437.654, with broad resistance to SCN. Restriction fragment analysis and sequence from BAC ends were used to develop a contig of PI 437.654 BACs representing the PI 437.654 counterpart of the Williams 82 BAC. Some of the markers on the PI 437.654 contig are separated by a greater physical distance (ca. 100 kb) than in the Williams 82 BAC, and some primers amplify bands from the mid-portion of the PI 437.654 BAC contig that are not amplified from the Williams 82 BAC. These observations suggest the presence of an insertion in the PI 437.654 genome relative to the Williams 82 genome. A high degree of multi-level duplication may be responsible for reported organizational instability in this part of the genome and supports the possibility of a deletion/insertion in this region.