A Hydroponic-Based Bioassay to Facilitate Plasmodiophora brassicae Phenotyping.

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is one of the most devastating diseases affecting the canola/oilseed rape (Brassica napus) industry worldwide. Currently, the planting of clubroot-resistant (CR) cultivars is the most effective strategy used to restrict the spread and the economic losses linked to the disease. However, virulent P. brassicae isolates have been able to infect many of the currently available CR cultivars, and the options to manage the disease are becoming limited. Another challenge has been achieving consistency in evaluating host reactions to P. brassicae infection, with most bioassays conducted in soil and/or potting medium, which requires significant space and can be labor intensive. Visual scoring of clubroot symptom development can also be influenced by user bias. Here, we have developed a hydroponic bioassay using well-characterized P. brassicae single-spore isolates representative of clubroot virulence in Canada, as well as field isolates from three Canadian provinces in combination with canola inbred homozygous lines carrying resistance genetics representative of CR cultivars available to growers in Canada. To improve the efficiency and consistency of disease assessment, symptom severity scores were compared with clubroot evaluations based on the scanned root area. According to the results, this bioassay offers a reliable, less expensive, and reproducible option to evaluate P. brassicae virulence, as well as to identify which canola resistance profile(s) may be effective against particular isolates. This bioassay will contribute to the breeding of new CR canola cultivars and the identification of virulence genes in P. brassicae that could trigger resistance and that have been very elusive to this day.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

A Basic Guide to the Propagation and Manipulation of the Clubroot Pathogen, Plasmodiophora brassicae.

Clubroot caused by the obligate parasite Plasmodiophora brassicae is a devastating disease affecting the canola industry worldwide. The socio-economic impact of clubroot can be significant, particularly in regions where Brassica crops are a major agricultural commodity. The disease can cause significant crop losses, leading to reduced yield and income for farmers. Extensive studies have been conducted to understand the biology and genetics of the pathogens and develop more effective management strategies. However, the basic procedures used for pathogen storage and virulence analysis have not been assembled or discussed in detail. As a result, there are discrepancies among the different protocols used today. The aim of this article is to provide a comprehensive and easily accessible resource for researchers who are interested in replicating or building upon the methods used in the study of the clubroot pathogen. Here, we discuss in detail the methods used for P. brassicae spore isolation, inoculation, quantification, propagation, and molecular techniques such as DNA extraction and PCR. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Extraction of Plasmodiophora brassicae resting spores and propagation Support Protocol 1: Evans blue staining to identify resting spore viability Support Protocol 2: Storage of Plasmodiophora brassicae Basic Protocol 2: Generation of single spore isolates from P. brassicae field isolates Basic Protocol 3: Phenotyping of Plasmodiophora brassicae isolates Basic Protocol 4: Genomic DNA extraction from Plasmodiophora brassicae resting spores Basic Protocol 5: Molecular detection of Plasmodiophora brassicae.

The clubroot pathogen Plasmodiophora brassicae: A profile update.

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.

Detection of pancreatic adenocarcinoma using circulating fragments of fibrinogen.

BACKGROUND: There is an urgent need for biomarkers to detect pancreatic cancer in the early, potentially curable, stages. METHODS: We have used SELDI profiling to analyze serum from 75 patients with pancreatic cancer and 61 patients with nonmalignant pancreaticobiliary diseases. RESULTS: A peak in the SELDI spectra corresponding to a 53 residue fragment of the α-chain of fibrinogen is remarkably elevated in approximately 50% of the cancer patients. In addition, fibrinogen degradation products were measured using the DR-70 assay. The areas under the receiver operating characteristic curves for the SELDI-detected fibrinogen fragment, DR-70 and CA19-9 were 0.65, 0.75 and 0.86, respectively. Class prediction models using combinations of these markers did not increase the area under the receiver operating characteristic curve compared with CA19-9. The novel fibrinogen fragment was not elevated to the same extent in other malignancies but was elevated in some patients with benign pancreatic disease. CONCLUSION: Both the SELDI-detected fragment of fibrinogen and DR-70 are significantly elevated in the serum of pancreatic cancer patients. However, they do not seem to improve pancreatic cancer detection over CA19-9 alone.