Identification of Soybean Germplasm and Associated Molecular Markers with Resistance to Fusarium graminearum

Abstract

Soybean ranks second by total production of all crops grown in the United States. From surveys of soybean production regions in the US and Canada, seedling diseases have been consistently identified as one of the top five biotic limitations on yield for over two decades. The role of Fusarium graminearum as an aggressive member of this complex was unknown until relatively recently and, consequently, publicly and commercially available varieties with resistance to this pathogen are unavailable. To address the need for resistant germplasm and to improve our understanding of the genetic basis underlying the resistance, we screened a set of 208 accessions of soybean from the United States Department of Agriculture Soybean Germplasm Collection (USDA-SGC) under controlled greenhouse conditions. A ratio of the root weight of inoculated plants compared to mock-inoculated controls was used to evaluate the degree of resistance. A linear mixed model identified eight resistant accessions (PI 548311, PI 438500, PI 561318 A, PI 547690, PI 391577, PI 157484, PI 632418, and PI 70466 -3) with significantly higher resistance than the population mean. Previous genotyping publicly available through the SoyBase database was used in a genome-wide association study (GWAS) to determine single nucleotide polymorphism (SNP) markers associated with resistant and susceptible phenotypes. A total of five significant marker-trait associations (MTAs) were discovered on chromosomes Gm02, Gm03, Gm06, Gm07, and Gm13, each accounting for 4.8, 4.3, 3.8, 4.1, and 3.0% of the phenotypic variance, respectively. This study, thus, lays a foundation for the better dissection of germplasm resistant to F. graminearum.