P-056 - Integrating genetic, genomic, and transcriptomic analyses to decipher quantitative disease resistance against Sclerotinia sclerotiorum in Brassica napus

Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot (SSR), has a vast host range spanning over 400 plant species. Among these species are economically important crops, including oilseed rape (Brassica napus) where SSR can result in devastating yield and quality losses. The control of Sclerotinia under field conditions remains challenging limited SSR resistance within the B. napus gene pool. This study used two independent segregating populations of B. napus for SSR resistance. Genetic mapping in two high-density genetic maps containing 2.285 and 1.329 SNP markers respectively. QTL analysis revealed four QTLs explaining 8.2 % to 19.5 % of phenotypic variance. During Sclerotinia infection over 30000 genes are transcriptionally regulated, but through a combination of whole genome sequencing data with transcriptomic analysis the number of candidate genes was narrowed to under 400 genes localized within the QTL region. Among these candidate genes are interesting transcription factors like ERF106, WRKY20 and TGA4, which serve as potential targets of significantly differentially regulated miRNAs. Long-read sequencing data was further used to identify structural variations between the resistant and susceptible parent lines. These data demonstrate the molecular signatures of QTLs for SSR resistance in B. napus, which can help understand the molecular mechanisms underlying the QTLs and develop markers for breeding resistant varieties of B. napus.