| Title: | Identification of QTLs Associated with Partial Resistance to White Mold in Soybean Using Field-Based Inoculation |
| Authors: | Huynh, T., Bastien, M., Iquira, E., Turcotte, P., Belzile, F. |
| Source: | Crop Sci. 2010, 50(3):969-979 |
| Abstract: | White mold caused by Sclerotinia sclerotiorum (Lib.) de Bary can be an important cause of yield loss in soybean. Only partial resistance to this disease has been found to date, and little is known about the loci contributing to this resistance. The objectives of this study were to identify quantitative trait loci (QTL) associated with partial resistance to white mold progression on the main stem. One hundred eighty F4?derived lines from a cross between a partially resistant cultivar, Maple Donovan, and a susceptible cultivar, OAC Bayfield, were tested for resistance to white mold under field conditions with (2003 and 2004) or without irrigation (2005 and 2006). The resistance of the lines was assessed by measuring the length of lesions 7 d after inoculation with a mycelial suspension. These lines were genotyped with 128 simple sequence repeat markers, and three QTLs associated with lesion length were detected consistently (in at least three of the four trials). Two of the QTLs were located on LG C2 (chromosome 6) and the third was on LGI (chromosome 20). In these genomic regions, the favorable alleles came from Maple Donovan and contributed to a decrease in lesion length. Together, they accounted for 30.7 to 50.9% of lesion length variation across year trials. Selective phenotyping of 26 lines carrying contrasting alleles at these QTLs in four additional environments resulted in significant phenotypic contrasts between the two genotypic classes. |