Abstract
BackgroundSclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in soybean. Although many papers have reported different loci contributing to partial resistance, few of these were proved to reproduce the same phenotypic impact in different populations.ResultsIn this study, we identified a major quantitative trait loci (QTL) associated with resistance to SSR progression on the main stem by using a genome-wide association mapping (GWAM). A population of 127 soybean accessions was genotyped with 1.5 M SNPs derived from genotyping-by-sequencing (GBS) and whole-genome sequencing (WGS) ensuring an extensive genome coverage and phenotyped for SSR resistance. SNP-trait association led to discovery of a new QTL on chromosome 1 (Chr01) where resistant lines had shorter lesions on the stem by 29 mm. A single gene (Glyma.01 g048000) resided in the same LD block as the peak SNP, but it is of unknown function. The impact of this QTL was even more significant in the descendants of a cross between two lines carrying contrasted alleles for Chr01. Individuals carrying the resistance allele developed lesions almost 50% shorter than those bearing the sensitivity allele.ConclusionThese results suggest that the new region on chromosome 1 harbors a promising resistance QTL to SSR that can be used in soybean breeding program.
Highlights
Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in soybean
Marker distribution To achieve extensive genome coverage, we re-analyzed previously obtained sequence data (940 M single-end reads from ApeKI GBS libraries prepared from DNA of 530 elite Canadian soybean lines) using an improved SNP-calling pipeline (Fast-GBS) and a more recent version of the soybean reference genome
New quantitative trait loci (QTL) on Chr01 Within our association mapping panel of 127 Canadian soybean lines, we identified 7 SNPs significantly associated with SSR resistance falling in small segments of only two chromosomes 1 and 15
Summary
Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in soybean. Sclerotinia stem rot (SSR) is a significant disease that causes yield and quality loss in soybean in the northern United States and Canada. This disease is caused by Sclerotinia sclerotiorum, a necrotrophic Ascomycota, capable of infecting more than 408 different species [6]. The fungus infects the plant via the flower spreads through the stem causing bleaching, severe wilting and shredding of tissue [7]. The evaluation of SSR resistance is quite challenging in variable environmental conditions. It has been shown to produce consistent results and was used to investigate the genetic determinants of SSR resistance is soybean [4, 13, 15]
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