Abstract
Beet curly top virus (BCTV) reduces sugar beet yield and sucrose production in semi-arid sugar beet growing regions. Control of BCTV in commercial sugar beet cultivars is based on low to moderate genetic resistance and the use of neonicotinoid insecticide seed treatments which may be restricted in the future due to environmental concerns. The Kimberly ARS program has developed sugar beet double haploid breeding lines such as KDH4-9 (R) exhibiting strong resistance to BCTV. When KDH4-9 was crossed with the highly susceptible (S) line, KDH19-17, the BCTV resistance trait segregated into three distinct resistance groups in the F2 population. We used graded-pool sequencing to rapidly map QTLs through whole-genome sequencing and bulked-segregant analysis. Graded-pool sequencing of individuals from the R and S groups (segregating population) and parents when combined with transcriptome analysis, revealed resistance associated QTLs primarily localized in chromosome 3 and a few minor QTLs in chromosomes 1, and 2. Resistance related genes identified were Bevul.3G031800 (RNA transport), Bevul.1G037400 (DNA-directed RNA polymerase III), Bevul.2G154500 (amino acid transmembrane transport). The putative genomic markers associated with BCTV resistance in KDH4-9 will be valuable for future trait introgression into commercial cultivars.