Identification and QTL mapping of resistance to Turnip yellows virus (TuYV) in oilseed rape, Brassica napus

Abstract

Key message Partially dominant resistance to Turnip yellows virus associated with one major QTL was identified in the natural allotetraploid oilseed rape cultivar Yudal. Abstract 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 (BC 1) populations from the F 1 with either the susceptible or resistant parent revealed the dominant inheritance of the TuYV resistance. The QTL on ChrA04 was verified in the segregating BC 1 population. A second minor QTL on ChrC05 was identified in one of the two DYDH experiments, and it was not observed in the BC 1 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.

The incidence of turnip yellows virus in oilseed rape crops (Brassica napus L.) in three different regions of England over three consecutive growing seasons and the relationship with the abundance of flying Myzus persicae

“…This has created high selection pressure for resistance-breaking strains of TuYV. A further alternative source of resistance has been reported recently (Hackenberg et al 2019).…”

Fine Characterization of a Resistance Phenotype by Analyzing TuYV-Myzus persicae-Rapeseed Interactions

“…Yudal of a single dominant QTL on chromosome A04 that does not segregate with markers linked to the ‘R54’ resistance, suggesting independent origins of the TuYV resistances present in ‘R54’ and in cv. Yudal [ 24 ]. On the French market, the first rapeseed cultivar described for its TuYV-resistant phenotype was cv.…”

Consequences of the neonicotinoid seed treatment ban on oilseed rape production – what can be learnt from the Swedish experience?

“…Alternative CSFB control options include reducing tillage intensity, 42 intercropping oilseed rape with frost‐sensitive legumes, 43,44 or delaying seeding 45 (but see Valantin‐Morison et al 42 ). The efficacy of insecticide seed treatments for TuYV control might be limited to begin with, 46 and an alternative TuYV control option is to use TuYV‐resistant cultivars, 47 delay seeding to narrow the time window for aphids to vector the virus in the autumn or to use insecticide spraying against the aphids, although the availability of registered and effective products is currently limited. Alternatives to seed treatments for Phyllotreta flea beetle control include no‐till, 48–50 early seeding, 51,52 increased seeding rates 49,52,53 and insecticide spraying with pyrethroids based on economic thresholds 54 .…”