Genome-wide association study to identify soybean stem pushing resistance and lodging resistance loci

Abstract

Lodging resistance is an important objective for soybean [Glycine max (L.) Merr.] breeding, but selection for this trait has been difficult since the resistance is controlled by multiple genes, and these genes interact with the environment. A total of 130 of 139 lines constituting a soybean genome-wide association study panel were phenotyped for stem pushing resistance, which is defined as the push-back strength when the plant stem is inclined, by measuring the force required to push a stem to a 45° angle using a force gauge in a greenhouse, and also for lodging, plant height, seed yield, and maturity at three locations in total in eastern Canada in 2013 or 2017. Two quantitative trait loci (QTLs) for pushing resistance were identified on chromosome 5 and 11, and each QTL accounted for 16.0% of phenotypic variation. In our panel, the alleles for higher pushing resistance were always of lower frequency than the alternate allele. Examining the panel at these QTLs identified that higher pushing resistance was associated with lower lodging on chromosomes 5 and 11, and that the difference for lodging between alleles was significant on chromosome 5. There was no difference in plant height or yield at the QTL on chromosomes 5 or 11, while higher pushing resistance was associated with later maturity at both QTLs. The pushing resistance QTL on chromosome 11 will be useful for decreasing lodging in Canadian short-season soybean.