Early Aphanomyces resistance as key element for future robust sugarbeet varieties.
Aphanomyces cochlioides Drechs. is a soil-borne oomycete fungus causing both an acute seedling disease (damping-off) as well as a chronic rot of the mature root (black root) in sugarbeet. The pathogen can lead to serious damage in most sugar beet growing areas, including North America, Europe and Asia. Chemicals like Hymexazole (Tachigaren®) have been instrumental in protecting the early developmental stages against seedling death and protect the emerging plantlets from early infection, which contributes to heavy late root rot. While the late phase of Aphanomyces root rot has been addressed by breeding companies for a long time, genotypic variation for early Aphanomyces infection was of lower priority in part due to highly effective chemical protectants. Various sources of genotypic variability for early Aphanomyces have been reported, i.e., from wild beet resources or USDA germplasm. Within KWS, we have been working on early Aphanomyces resistance over the past years and are establishing routines for larger germplasm screenings. Current genetic variation is probably not strong enough to replace existing chemical protection but improvements would provide complementary safeguarding. The goal of our breeding approach is to integrate early Aphanomyces resistance into variety development to further strengthen the defense line against soil-borne diseases. Along with an overall improved root and leaf healthiness and disease resistance packages this shall serve as a key element for future robust sugar beet varieties.