Mapping soybean aphid resistance genes in PI 567598B

Area of Science:

• Plant Genetics
• Agricultural Entomology
• Molecular Biology

Background:

• Soybean aphid (Aphis glycines Matsumura) is a significant North American pest of soybean (Glycine max).
• Previous research identified two recessive genes conferring strong aphid resistance in plant introduction (PI) 567598B.

Purpose of the Study:

• To map the two aphid resistance genes from PI 567598B onto the soybean genetic linkage map using molecular markers.
• To understand the genetic basis and interaction of soybean aphid resistance.

Main Methods:

• Developed a mapping population of 282 F4:5 soybean lines from a cross between IA2070 and E06902.
• Evaluated aphid resistance in field (2009) and greenhouse (2010) trials.
• Employed composite and multiple interval mapping to identify quantitative trait loci (QTLs).
• Confirmed findings with a second population of 94 F2:5 lines.

Main Results:

• Two QTLs for aphid resistance were mapped to soybean chromosomes 7 (linkage group M) and 16 (linkage group J).
• The QTL on chromosome 16 conferred resistance across all trials and isolates.
• The QTL on chromosome 7 provided resistance in greenhouse trials but was overcome by the 2009 field isolate.
• Significant epistatic interaction was observed between the two QTLs.
• Each QTL explained substantial phenotypic variation (up to 30% individually, and combined up to 80.4% in the second population).

Conclusions:

• The soybean aphid resistance from PI 567598B is controlled by two major QTLs on chromosomes 7 and 16.
• Chromosome 16 QTL offers broad-spectrum resistance, while chromosome 7 QTL's efficacy is isolate-dependent.
• These QTLs and their interaction are valuable for marker-assisted breeding strategies to enhance soybean aphid resistance.