Tuesday, November 14, 2006

QTL for soybean seed yield and agronomic traits in populations derived from exotic lines.

Nanda Chakraborty1, Joe Curley1, David J. Neece2, Brian Diers1, and Randall L. Nelson3. (1) Univ of Illinois, 263A NSRC, 1101 W. Peabody Drive, Urbana, IL 61801, (2) USDA-ARS, 234 NSRC, 1101 W. Peabody Drive, Urbana, IL 61801, (3) USDA-ARS/Univ. of Illinois, 1101 West Peabody, Urbana, IL 61801

Previous studies have reported that seed yield in soybean can be improved by using PIs as sources of favorable alleles. Therefore the objective of this study was to identify unique alleles in populations derived from exotic soybean lines. The A3 population consists of 133 F4:6 lines developed from four exotic lines and the domestic parent IA3023. The B3 population consists of 149 F4:6 lines developed from two exotic lines and the domestic parent U98-311442. Both populations were evaluated in 2005 at two locations in Illinois for plant height, lodging, maturity and seed yield. Both populations showed a significant genotypic effect and no environment by genotype interaction. High heritability for yield ranging from 0.78 to 0.83 was detected in both populations. In the A3 population 7 QTLs were detected for agronomic traits, including one QTL for yield in which the favorable allele, derived from the domestic parent, increased yield by 270 kg/ha. The B3 population showed transgressive segregation for yield with the top ten progeny lines exceeding the domestic parent by 536 - 670 kg/ha, with LSD of 295 kg/ha. A total of eleven QTLs were detected in the B3 population for agronomic traits including yield. Two QTLs for yield, one on LG A1 and the other on LG G, were detected consistently over environments. The LOD ranged from 2.7 to 5.2 and the QTLs explained 9.2 to 18.0 % of the phenotypic variation. The QTL on A1 is located 2 cM from a previously reported yield QTL. The QTL on G is located at Satt610, a location where, to our knowledge, a yield QTL has not been previously reported. The domestic parent contributes the favorable allele, causing a yield boost of 281 kg/ha. Results on E population developed from two backcrosses of Elgin to exotic germplasm will also be presented.