Jean-Claude Pruvot, head of Corteva oilseed rape research for Europe, who was part of the team developing the new trait, says: “With no known sclerotinia resistance in commercial varieties in Canada or Europe, our team has developed, through conventional breeding, sclerotinia tolerant material by collecting Asiatic sources.
With several cycles of recurrent selection, the team cumulated many genes contributing to disease tolerance with different modes of action.”
After several years of selection and stringent sclerotinia screening, the team identified inbreds with winter growth habits and strong disease tolerance, which would be used as the base germplasm for sclerotinia hybrid development.
Mr Pruvot says: “This material used in our hybrid breeding programme has demonstrated very good combining ability with high yield potential, showing the benefit of exotic blood.” Sclerotinia resistance is expressed in the leaf where it reduces disease entry points and in the stem where it helps to prevent spread of the disease throughout the plant.
Precise evaluation of the trait is made on disease incidence and severity – the two factors that are being reduced by genetic mechanisms.
As infection is highly dependent on weather conditions around flowering, hybrids are characterised for sclerotinia tolerance in multiple sites across Europe to be exposed to different weather patterns at flowering.
Mr Pruvot adds: “As the sclerotinia source has been [introduced] into our germplasm it exhibits the strengths of our conventional material – high oil, strong lodging tolerance and solid phoma and light leaf spot tolerance.
On top of this, it has turnip yellows virus tolerance, validated in French official trials.
“This is the kind of hybrid with broad commercialisation we are targeting in our strategy.”