Explore the vast range of titles available.

Brassica spp. production can be negatively affected by clubroot, which is caused by the protozoan Plasmodiophora brassicae Woronin. Most of the information on clubroot control is derived from studies in temperate regions. Here, management strategies were evaluated to reduce broccoli (Brassica oleracea L. var. italica Plenck) crop losses owing to clubroot in tropical mountain regions. The first experiment revealed the effect of green manure from coriander (Coriandrum sativum L.), sunn hemp (Crotalaria juncea L.), sweet corn (Zea mays L.), and spontaneous vegetation (control) associated with broccoli seedlings of 4 different sizes. In the second experiment, the effect of soil amendments (limestone and steel slag) in conjunction with poultry litter (fresh or composted for 45 days) and without poultry litter (control), was assessed. Both field experiments sought to evaluate the disease intensity, plant development (root growth, biomass, and nutrient accumulation), and yield. Sunn hemp and coriander biomass resulted in higher healthy root volumes and dry weights of broccoli. However, such benefits were not derived from corn treatment. Compared to smaller seedlings (10 mL cell and 20 days of age, and 16 mL cell and 24 days of age), the use of larger seedlings (35 mL cell and 28 days of age, and 50 mL cell and 32 days of age) resulted in lower intensity of clubroot and increased the average yield by 143% in summer crops. Steel slag, like limestone, corrected soil acidity and resulted in plant growth; however, clubroot intensity was not significantly affected. Fresh and composted poultry litter increased the percentage of diseased roots compared with the control; however, broccoli yield was not affected by the treatments. Using green manure (sunn hemp or coriander) and well-developed seedlings is recommended as a strategy to reduce losses induced by clubroot during broccoli cultivation.

The effects of the dose and application method of limestone - broadcast or in furrow - and of agricultural gypsum on soil fertility, the control of clubroot, and cauliflower development in mountain farming areas were evaluated. Initially, four doses of broadcast limestone (0.0, 1.0, 2.0, and 4.0 Mg ha-1) and two cauliflower cultivars (Sharon and Piracicaba Precoce) were analyzed. A second experiment evaluated limestone (4.0 Mg ha-1) application treatments: broadcast and in furrow, broadcast limestone + gypsum (3.0 + 1.0 Mg ha-1), and broadcast gypsum (1.0 Mg ha-1). Soil fertility was improved, and significant increases were observed in the total and healthy root volume with increasing doses of limestone. With 4.0 Mg ha-1, a 58 and 85% increase in yield was observed in Sharon and Piracicaba, respectively, compared to the control. Treatments with limestone and limestone + gypsum, regardless of the application method, elevated pH (≥ 10%), base saturation (V%) (≥ 37%), and calcium (Ca) contents (≥ 100%), and reduced the levels of aluminum ions (Al3+) (≥ 60%) and clubroot severity (≥ 64%) and favored biomass accumulation (≥ 27%) and yield (≥ 9.2%). The application of limestone in the furrow yielded results similar to the broadcast application.

Analysis of the ribosomal introns of Plasmodiophora brassicae populations infecting the cruciferous weed Cardamine occulta revealed the complex dynamics of size, intraspecific variability, and distribution. The results showed that P. brassicae populations from the weed have lost multiple introns in the small and large subunits of the ribosomal RNA genes. Moreover, the retained introns, despite a largely mutual share of conserved parts with the cosmopolitan strains, contained numerous novel structures. These structural differences comprise a high level of polymorphisms, such as transversion point mutations occurring at sites involving the intronic splicing sites or insertions/deletions at the binding sites. Two geographical P. brassicae populations from C. occulta carried a lengthy intron-encoded ORF and putative mobile elements established in the large subunit. A few P. brassicae populations from the Brassica crops also harbored polymorphic introns that shared common mutated motifs with the weed-affecting group. The diversity of ribosomal introns observed from those investigated populations demonstrated the genetic distinction of the P. brassicae populations from C. occulta. The genetic variations might play a key role in the adaptability of the weed-infecting populations and are more likely related to the process of pathogenesis for the cosmopolitan P. brassicae infecting the Brassica crops.

Background Plasmodiophora brassicae is the causal agent of clubroot disease of cruciferous plants and one of the biggest threats to the rapeseed (Brassica napus) and brassica vegetable industry worldwide. Disease symptoms In the advanced stages of clubroot disease wilting, stunting, yellowing, and redness are visible in the shoots. However, the typical symptoms of the disease are the presence of club‐shaped galls in the roots of susceptible hosts that block the absorption of water and nutrients. Host range Members of the family Brassicaceae are the primary host of the pathogen, although some members of the family, such as Bunias orientalis, Coronopus squamatus, and Raphanus sativus, have been identified as being consistently resistant to P. brassicae isolates with variable virulence profile. Taxonomy Class: Phytomyxea; Order: Plasmodiophorales; Family: Plasmodiophoraceae; Genus: Plasmodiophora; Species: Plasmodiophora brassicae (Woronin, 1877). Distribution Clubroot disease is spread worldwide, with reports from all continents except Antarctica. To date, clubroot disease has been reported in more than 80 countries. Pathotyping Based on its virulence on different hosts, P. brassicae is classified into pathotypes or races. Five main pathotyping systems have been developed to understand the relationship between P. brassicae and its hosts. Nowadays, the Canadian clubroot differential is extensively used in Canada and has so far identified 36 different pathotypes based on the response of a set of 13 hosts. Effectors and resistance After the identification and characterization of the clubroot pathogen SABATH‐type methyltransferase PbBSMT, several other effectors have been characterized. However, no avirulence gene is known, hindering the functional characterization of the five intercellular nucleotide‐binding (NB) site leucine‐rich‐repeat (LRR) receptors (NLRs) clubroot resistance genes validated to date. Important Link Canola Council of Canada is constantly updating information about clubroot and P. brassicae as part of their Canola Encyclopedia: https://www.canolacouncil.org/canola‐encyclopedia/diseases/clubroot/. Phytosanitary categorization PLADBR: EPPO A2 list; Annex designation 9E. The clubroot pathogen wants to conquer the world, and how better than through social media. This Plasmodiophora brassicae profile highlights how the growers are in a constant fight with this devastating pathogen. Art by C.‐É. Brochu.

The bacterial community in soil was screened by using various molecular approaches for bacterial populations that were activated upon addition of different supplements. Plasmodiophora brassicae spores, chitin, sodium acetate, and cabbage plants were added to activate specific bacterial populations as an aid in screening for novel antagonists to plant pathogens. DNA from growing bacteria was specifically extracted from the soil by bromodeoxyuridine immunocapture. The captured DNA was fingerprinted by terminal restriction fragment length polymorphism (T-RFLP). The composition of the dominant bacterial community was also analyzed directly by T-RFLP and by denaturing gradient gel electrophoresis (DGGE). After chitin addition to the soil, some bacterial populations increased dramatically and became dominant both in the total and in the actively growing community. Some of the emerging bands on DGGE gels from chitin-amended soil were sequenced and found to be similar to known chitin-degrading genera such as Oerskovia, Kitasatospora, and Streptomyces species. Some of these sequences could be matched to specific terminal restriction fragments on the T-RFLP output. After addition of Plasmodiophora spores, an increase in specific Pseudomonads could be observed with Pseudomonas-specific primers for DGGE. These results demonstrate the utility of microbiomics, or a combination of molecular approaches, for investigating the composition of complex microbial communities in soil.

Clubroot disease is a soil-borne disease caused by Plasmodiophora brassicae. It occurs in cruciferous crops exclusively, and causes serious damage to the economic value of cruciferous crops worldwide. Although different measures have been taken to prevent the spread of clubroot disease, the most fundamental and effective way is to explore and use disease-resistance genes to breed resistant varieties. However, the resistance level of plant hosts is influenced both by environment and pathogen race. In this work, we described clubroot disease in terms of discovery and current distribution, life cycle, and race identification systems; in particular, we summarized recent progress on clubroot control methods and breeding practices for resistant cultivars. With the knowledge of these identified resistance loci and R genes, we discussed feasible strategies for disease-resistance breeding in the future.

Clubroot, caused by Plasmodiophora brassicae , is an important disease of Brassica crops worldwide. F 1 progeny from the Brassica rapa lines T19 (resistant) × ACDC (susceptible) were backcrossed with ACDC, then self-pollinated to produce BC 1 S 1 lines, From genotyping-by-sequencing (GBS) of the parental lines and BC 1 plants, about 1.32 M sequences from T19 were aligned into the reference genome of B . rapa with 0.4-fold coverage, and 1.77 M sequences with 0.5-fold coverage in ACDC. The number of aligned short reads per plant in the BC 1 ranged from 0.07 to 1.41 M sequences with 0.1-fold coverage. A total of 1584 high quality SNP loci were obtained, distributed on 10 chromosomes. A single co-localized QTL, designated as Rcr4 on chromosome A03, conferred resistance to pathotypes 2, 3, 5, 6 and 8. The peak was at SNP locus A03_23710236, where LOD values were 30.3 to 38.8, with phenotypic variation explained (PVE) of 85–95%. Two QTLs for resistance to a novel P . brassicae pathotype 5x, designated Rcr8 on chromosome A02 and Rcr9 on A08, were detected with 15.0 LOD and 15.8 LOD, and PVE of 36% and 39%, respectively. Bulked segregant analysis was performed to examine TIR-NBS-LRR proteins in the regions harboring the QTL.

The rapid spread of clubroot disease, which is caused by , threatens Brassicaceae crop production worldwide. Breeding plants that have broad-spectrum disease resistance is one of the best ways to prevent clubroot. In the present study, eight Chinese cabbage germplasms were screened using published clubroot-resistant (CR) loci-/gene-linked markers. A CR gene Crr3 potential carrier \"85-74\" was detected which linked to marker BRSTS61; however, \"85-74\" shows different responses to local pathogens \"LAB-19,\" \"LNND-2,\" and \"LAB-10\" from \"CR-73\" which harbors Crr3. We used a next-generation sequencing-based bulked segregant analysis approach combined with genetic mapping to detect CR genes in an F segregant population generated from a cross between the Chinese cabbage inbred lines \"85-74\" (CR) and \"BJN3-1\" (clubroot susceptible). The \"85-74\" line showed resistance to a local pathogen \"LAB-19\" which was identified as race 4; a genetic analysis revealed that the resistance was conferred by a single dominant gene. The CR gene which we named was mapped to a 60 kb (1 cM) region between markers yau389 and yau376 on chromosome A03. is located upstream of which was confirmed based on the physical positions of linked markers. The identification of linked markers can be applied to marker-assisted selection in the breeding of new CR cultivars of Chinese cabbage and other crops.

Two cabbage ( Brassica oleracea ) cultivars ‘Tekila’ and ‘Kilaherb’ were identified as resistant to several pathotypes of Plasmodiophora brassicae . In this study, we identified a clubroot resistance gene ( Rcr7 ) in ‘Tekila’ for resistance to pathotype 3 of P. brassicae from a segregating population derived from ‘Tekila’ crossed with the susceptible line T010000DH3. Genetic mapping was performed by identifying the percentage of polymorphic variants (PPV), a new method proposed in this study, through bulked segregant RNA sequencing. Chromosome C7 carried the highest PPV (42%) compared to the 30–34% in the remaining chromosomes. A peak with PPV (56–73%) was found within the physical interval 41–44 Mb, which indicated that Rcr7 might be located in this region. Kompetitive Allele-Specific PCR was used to confirm the association of Rcr7 with SNPs in the region. Rcr7 was flanked by two SNP markers and co-segregated with three SNP markers in the segregating population of 465 plants. Seven genes encoding TIR-NBS-LRR disease resistance proteins were identified in the target region, but only two genes, Bo7g108760 and Bo7g109000 , were expressed. Resistance to pathotype 5X was also mapped to the same region as Rcr7 . B. oleracea lines including ‘Kilaherb’ were tested with five SNP markers for Rcr7 and for resistance to pathotype 3; 11 of 25 lines were resistant, but ‘Kilaherb’ was the only line that carried the SNP alleles associated with Rcr7 . The presence of Rcr7 in ‘Kilaherb’ for resistance to both pathotypes 3 and 5X was confirmed through linkage analysis.

Clubroot, caused by Plasmodiophora brassicae, is an important soilborne disease of canola (Brassica napus) in Alberta, Canada. Genetic resistance is the most effective clubroot management tool, and resistant cultivars are grown extensively in affected regions. In 2013, relatively severe symptoms of clubroot were observed in some fields of resistant canola. In greenhouse tests, four populations of P. brassicae from two of these fields caused significantly increased levels of clubroot on the cultivars from which they had been first recovered; these included three populations (L-G1, L-G2 and L-G3) recovered from the cultivar ‘L135C’, and one population (D-G3) recovered from ‘D3152’. Further testing showed that L-G1, L-G2 and L-G3 were highly virulent on a suite of six resistant canola cultivars (‘45H29’, ‘D3152’, ‘74–47CR’, ‘1960’, ‘L135C’ and ‘6056CR’) representing a cross-section of products available in Canada, while a seventh cultivar (‘9558c’) was moderately resistant to moderately susceptible. Bioassays of field soil with a dozen clubroot-resistant host genotypes confirmed that in most cases, resistance was no longer effective. Host responses to the population D-G3 were more variable, with most cultivars developing intermediate levels of disease. All four P. brassicae populations were classified as pathotypes 5, P₃ and 16/6/8 on the differentials of Williams, Somé et al., and the European Clubroot Differential set. The pathotype classifications, however, do not reflect the increased virulence of these populations on clubroot-resistant canola. The identification of new virulence phenotypes of P. brassicae capable of overcoming genetic resistance underscores the need for increased stewardship of resistance sources.