Studies of clubroot (Plasmodiophora brassicae) on oilseed rape in the Czech Republic

Abstract: Clubroot caused by the pathogen Plasmodiophora brassicae (Wor.) has been spreading on winter oilseed rape in Czech Republic for the last three years. Research on P. brassicae in Czech Republic is therefore important for the adoption of management strategies against the disease under Czech environmental conditions. Pilot experiments with clubroot resistant cultivars of winter rape started in 2012. Experiments were made in greenhouse and field conditions. For greenhouse experiments, soil samples were collected from contaminated fields. Seeds of oilseed rape varieties declared by seed companies as resistant together with susceptible controls (variety Rohan and chinese cabbage variety Granaat) were sown both into soil samples and in the field that was severely and homogeneously contaminated by P. brassicae. Incidence and severity of symptoms on roots were evaluated after eight weeks. Presence of P. brassicae in roots was tested by PCR. Results obtained from both experiments were almost identical. Resistant cultivars Mendel, Mendelson, Alister and Andromeda showed no visible symptoms in any soil sample, although PCR confirmed pathogen presence in all cases. Similarly, the soil samples were also tested for the presence of P. brassicae using PCR. Furthermore, testing of soil samples at different dilutions by RealTime-PCR using TaqMan probes and SYBR green is in progress. The monitoring of clubroot P. brassicae pathotypes diversity in the Czech Republic is also planned and has already started.