Abstract
Key messagePartially dominant resistance to Turnip yellows virus associated with one major QTL was identified in the natural allotetraploid oilseed rape cultivar Yudal.Turnip yellows virus (TuYV) is transmitted by the peach-potato aphid (Myzus persicae) and causes severe yield losses in commercial oilseed rape crops (Brassica napus). There is currently only one genetic resource for resistance to TuYV available in brassica, which was identified in the re-synthesised B. napus line ‘R54’. In our study, 27 mostly homozygous B. napus accessions, either doubled-haploid (DH) or inbred lines, representing a diverse subset of the B. napus genepool, were screened for TuYV resistance/susceptibility. Partial resistance to TuYV was identified in the Korean spring oilseed rape, B. napus variety Yudal, whilst the dwarf French winter oilseed rape line Darmor-bzh was susceptible. QTL mapping using the established Darmor-bzh × Yudal DH mapping population (DYDH) revealed one major QTL explaining 36% and 18% of the phenotypic variation in two independent experiments. A DYDH line was crossed to Yudal, and reciprocal backcross (BC1) populations from the F1 with either the susceptible or resistant parent revealed the dominant inheritance of the TuYV resistance. The QTL on ChrA04 was verified in the segregating BC1 population. A second minor QTL on ChrC05 was identified in one of the two DYDH experiments, and it was not observed in the BC1 population. The TuYV resistance QTL in ‘R54’ is within the QTL interval on Chr A04 of Yudal; however, the markers co-segregating with the ‘R54’ resistance are not conserved in Yudal, suggesting an independent origin of the TuYV resistances. This is the first report of the QTL mapping of TuYV resistance in natural B. napus.
Highlights
Oilseed rape (OSR; Brassica napus; genome AACC, 2n = 38) is the second most important oilseed crop after soybean in the world; in Europe, OSR is the major source of vegetable oil, oilseed meals and biodiesel (Carré and Pouzet 2014)
Turnip yellows virus (TuYV) resistance phenotyping of Darmor‐bzh × Yudal DH lines
The susceptibility of B. napus plant lines to TuYV varied based on virus titres determined 6 weeks after infection using TAS-ELISA
Summary
Oilseed rape (OSR; Brassica napus; genome AACC, 2n = 38) is the second most important oilseed crop after soybean in the world; in Europe, OSR is the major source of vegetable oil, oilseed meals and biodiesel (Carré and Pouzet 2014). Annual global production of OSR has doubled since 2000 (FAO 2018) and reached 76.2 million tonnes in 2017, which is equivalent to 14% of the worldwide oilseed crop production. OSR and vegetable brassicas, are not reaching their full yield potential in the UK. The average yield for oilseed rape in the UK (3.4 tonne/ha) (DEFRA 2018) is clearly below the estimated potential yields of current cultivars (6.5–7 tonne/ ha) (Berry and Spink 2006).
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