Clubroot presents a serious threat to cultures of oilseed rape, especially if the share of this plant species in sowing structure is high. This is related to a long-lasting survival of pathogens resting spores in soil. The casual disease agent is Plasmodiophora brassicae Woronin -an obligatory, internal pathogen of Brassicae family which causes the formation of tumors on roots and hypocotyls. Plants with disease symptoms have a confined ability of nutrients' and water uptake and this may cause considerable losses in quantity and quality of potential yield. Monitoring performed in cultivation areas and the information obtained from farmers allowed to confirm a threat of disease occurrence in several voivodeships. At the same time there is a serious danger of the infection spread to other regions of oilseed rape crops.Confining plant infection by clubroot pathogen may be obtained mainly by applying a correct crop rotation, and also by providing resistant varieties for cultivation. In the performed greenhouse experiment, reaction to the infection caused by P. brassicae of chosen winter oilseed rape cultivars was studied. The degree of plant infection was assessed at the growth phase of green bud. It was stated that cv. Mendel revealed significantly the lowest degree of infection, as compared to the other studied cultivars. The other tested varieties were infested in a differentiated degree, however these differences were mostly not confirmed statistically. The infection level was mainly dependent on places of soil derivation.

Clubroot, caused by Plasmodiophora brassicae infection, is a disease of growing importance in cruciferous crops, including oilseed rape (Brassica napus). The affected plants exhibit prominent galling of the roots that impairs their capacity for water and nutrient uptake, which leads to growth retardation, wilting, premature ripening, or death. Due to the scarcity of effective means of protection against the pathogen, breeding of resistant varieties remains a crucial component of disease control measures. The key aspect of the breeding process is the identification of genetic factors associated with variable response to the pathogen exposure. Although numerous clubroot resistance loci have been described in Brassica crops, continuous updates on the sources of resistance are necessary. Many of the resistance genes are pathotype-specific, moreover, resistance breakdowns have been reported. In this study, we characterize the clubroot resistance locus in the winter oilseed rape cultivar “Tosca.” In a series of greenhouse experiments, we evaluate the disease severity of P. brassicae-challenged “Tosca”-derived population of doubled haploids, which we genotype with Brassica 60 K array and a selection of SSR/SCAR markers. We then construct a genetic map and narrow down the resistance locus to the 0.4 cM fragment on the A03 chromosome, corresponding to the region previously described as Crr3. Using Oxford Nanopore long-read genome resequencing and RNA-seq we review the composition of the locus and describe a duplication of TIR-NBS-LRR gene. Further, we explore the transcriptomic differences of the local genes between the clubroot resistant and susceptible, inoculated and control DH lines. We conclude that the duplicated TNL gene is a promising candidate for the resistance factor. This study provides valuable resources for clubroot resistance breeding programs and lays a foundation for further functional studies on clubroot resistance.

Stem canker of brassicas is one of the most damaging diseases of oilseed rape worldwide. The disease is caused by two related Leptosphaeria species, and L. maculans is regarded as the more damaging one. Being an ascomycete, the pathogen is able to quickly create new variants that can overcome new resistance genes introduced by researchers and breeding companies. The aim of this work was to study polymorphism of L. maculans populations using 10 recently developed minisatellite markers. The studied subpopulations differed with metconazole treatment.Seven minisatellite markers showed polymorphisms and formed alleles varying from 2 to 10 different core motifs, with 5 alleles on average. In total 36 alleles were found. The majority of alleles (72%) were found in both studied subpopulations of L. maculans.There were 28 alleles in the group of L. maculans isolates originating from plants not treated with any fungicide and 32 in the subpopulation treated with metconazole. Ten unique alleles and imbalanced ratios between some alleles contributed to differences between L. maculans subpopulations. The minisatellites MinLm555, MinLm935-2, MinLm939, MinLm1139 and MinLm2451 showed 6 new variants as compared to the isolates described so far.

There has been a rapid, worldwide increase in oilseed rape production that has resulted in enormous intensification of oilseed rape cultivation, leading to tight rotations. This in turn, has caused an accumulation of pests as well as foliar and soil-borne diseases. Recently, clubroot has become one of the biggest concerns of oilseed rape growers. Clubroot is caused by the soil-borne protist Plasmodiophora brassicae Woronin. The pathogen may be present in groundwater, lakes, and irrigation water used in sprinkling systems. It can be easily transmitted from one field to another not only by water, but also by soil particles and dust transmitted by wind and on machinery. The aim of our overall study was to check for P. brassicae infestation of Polish agricultural soils. This paper presents the 2012 results of a study performed along the Polish-Ukrainian border in two provinces: Lublin (Lubelskie Voivodeship) and the Carpathian Foothills (Podkarpackie Voivodeship), in south-east Poland. Monitoring was done in 11 counties, including nine rural and two municipal ones. In total, 40 samples were collected, out of which 36 were collected from fields located in rural areas and four from municipal areas, with two per municipal region. Each sample was collected at 8-10 sites per field, using a soil auger. The biotest to detect the presence of P. brassicae was done under greenhouse conditions using seedlings of the susceptible Brassicas: B. rapa ssp. pekinensis and the Polish variety of oilseed rape B. napus cv. Monolit. Susceptible plants grown in heavily infested soils produced galls on their roots. A county was regarded as free from the pathogen, if none of the bait plants became infected. The pathogen was found in three out of 40 fields monitored (7.5%) in the Carpathian Foothill region. The fields were located in two rural counties. The pathogen was not found in Lublin province, and was also not detected in any of the municipal counties. The detection with a biotest was fully confirmed by PCR-based molecular detection of P. brassicae DNA in soil samples.

The study presents the results of research on the influence of a mineral growth stimulant containing titanium (Ti) in the form available to plants, applied to reduce the effects of biotic stresses caused by agrophages, namely fungal pathogens and selected insect pests. The study was conducted in 2014 and 2015 on winter oilseed rape, winter wheat, and maize. The purpose of the study was to determine the influence of the Ti-containing stimulant on the degree of damage caused by major pests occurring in the crops (cabbage seed weevil, cereal leaf beetle, and European corn borer), the degree of infestation with fungal diseases (gray mold, Alternaria disease, eyespot, foot rot, sooty mold, glume blotch, Fusarium head blight, Fusarium stalk rot, maize smut, and brown spot), and yield parameters. The study showed that the stimulant containing Ti successfully reduced the occurrence of pest damage to winter rapeseed and winter wheat plants and the occurrence of diseases in winter rapeseed, winter wheat, and maize crops. Thus, the application of the Ti stimulant resulted in an increased yield of the crops being tested. The main factor explaining this phenomenon is unknown, and it is probably the result of several factors. The study contains the discussion on this phenomenon.