Gene ruiz dating
The detached leaflet tests were replicated as follows: 3 leaflets/genotype × 2 replications × 2 dates were tested in 2007, 3 leaflets/genotype × 2 replications in 2008 and 3 leaflets/genotype × 2 replications × 2 dates in 2010.
Three tuber slices/genotype × 2 replications were tested in 2006, 20. possessing the R gene, when its mean resistance score in both detached leaflet and in tuber slice tests was ≥ 7.
Detached leaflets or tuber slices were inoculated with a 30 μl droplet of sporangia/zoospore suspension (50 sporangia/μl).
After incubation of 6 days at 16°C, in high humidity and, in case of leaflets, under constant light of about 1,600 lx, they were scored using a 1-9 scale, where 9 is maximum resistant .
Cvs Gloria and Robijn and clone DG 94-668 proved more susceptible than expected.
In tuber slice tests, cvs Sárpo Mira and Robijn and clone DG 94-15 showed some level of resistance to ).
Some potentially durable, broad-spectrum resistance genes against this disease have been described recently.All these are based on avoiding monocultures and use of as many broad-spectrum R genes as possible.These can either be stacked within cultivars or used in mixtures of breeding lines each containing a different R gene.Most of the standards performed as expected with cv.Sárpo Mira being highly resistant and cvs Biogold and Escort and clone DG 94-15 being moderately resistant in detached leaflet tests.
The marker-trait association with the closest marker, violet flower colour, explained 87.1% and 85.7% of variance, respectively, for mean detached leaflet and tuber slice resistance.