Fouad Daayf

University of Manitoba | UMN · Department of Plant Science

Genomics has emerged as a great tool in enhancing our understanding of the biology of Verticillium species and their interactions with the host plants. Through different genomic approaches, researchers have gained insights into genes, pathways and virulence factors that play crucial roles in both Verticillium pathogenesis and the defense responses...

Phytophthora infestans is the most economically important pathogen of potato and tomato worldwide. Preventative fungicide spraying remains the most effective management option for controlling late blight caused by P. infestans. Worldwide, plant protection products against late blight are costing producers several billions of dollars annually. Incre...

Late blight caused by Phytophthora infestans is an economically important disease of potato and tomato worldwide. In Canada, increases in late blight incidence and severity coincided with changes in the genetic composition of P. infestans. We monitored late blight incidence on tomato and potato crops in Pacific western and eastern Canada between 20...

A highly aggressive strain (CMN14-5-1) of Clavibacter nebraskensis bacteria, which causes Goss’s wilt in corn, induced severe symptoms in a susceptible corn line (CO447), resulting in water-soaked lesions followed by necrosis within a few days. A tolerant line (CO450) inoculated with the same strain exhibited only mild symptoms such as chlorosis, f...

In fungal plant pathogens, genome rearrangements followed by selection pressure for adaptive traits have facilitated the co-evolutionary arms race between hosts and their pathogens. Pyrenophora tritici-repentis (Ptr) has emerged recently as a foliar pathogen of wheat worldwide and its populations consist of isolates that vary in their ability to pr...

Polyketides are structurally diverse and physiologically active secondary metabolites produced by many organisms, including fungi. The biosynthesis of polyketides from acyl-CoA thioesters is catalyzed by polyketide synthases, PKSs. Polyketides play roles including in cell protection against oxidative stress, non-constitutive (toxic) roles in cell m...

Pyrenophora tritici-repentis pangenome

We sequenced the genome of a global collection (40 isolates) of the fungus Pyrenophora tritici-repentis (Ptr), a major foliar pathogen of wheat and model for the evolution of necrotrophic pathogens. Ptr exhibited an open-pangenome, with 43% of genes in the core set and 57% defined as accessory (present in only a subset of isolates), of which 56% we...

NADPH oxidase (Nox) genes are responsible for Reactive Oxygen Species (ROS) production in living organisms such as plants, animals, and fungi, where ROS exert different functions. ROS are critical for sexual development and cellular differentiation in fungi. In previous publications, two genes encoding thioredoxin and NADH-ubiquinone oxidoreductase...

Fusarium head blight (FHB) can lead to dramatic yield losses and mycotoxin contamination in small grain cereals in Canada. To assess the extent and severity of FHB in oat, samples collected from 168 commercial oat fields in the province of Manitoba, Canada, during 2016–2018 were analyzed for the occurrence of Fusarium head blight and associated myc...

In Oct. 2019, soybean plants (Glycine max) (cv. 24-10RY, R7 growth stage) with dry rot, necrosis, reddish-brown lesions, and small black fruiting bodies in linear rows were collected from fields in Manitoba (Carman, St. Adolph, Dauphin), Canada. The pods and seeds were shrivelled, small and some seeds were covered with whitish mycelium. Symptoms be...

Metabolomics identify and analyze, in a comprehensive and high throughput manner, all the metabolites of an organism including amino acids, organic acids, sugars, fatty acids, lipids, steroids, small peptides, vitamins and phenolics. By measuring global sets of low molecular weight metabolites, metabolomics provide a snapshot readout of metabolic a...

Verticillium dahliae is a hemibiotrophic pathogen responsible for great losses in dicot crop production. An ExoPG gene (VDAG_03463,) identified using subtractive hybridization/cDNA-AFLP, showed higher expression levels in highly aggressive than in weakly aggressive V. dahliae isolates. We used a vector-free split-marker recombination method with PE...

Soybean is threatened by many pathogens that negatively affect this crop's yield and quality, e.g., different Fusarium species that cause wilting and root rot diseases. Fusarium root rot (FRR) in soybean can be caused by F. graminearum and other Fusarium spp. that are associated with Fusarium head blight (FHB) in cereals. Therefore, it was importan...

Quantitative real-time PCR was used to monitor the expression of 15 Verticillium dahliae’s genes, putatively involved in pathogenicity, highly (HAV) and weakly aggressive (WAV) V. dahliae isolates after either (i) elicitation with potato leaf, stem, or root extracts, or (ii) inoculation of potato detached petioles. These genes, i.e., coding for Ras...

The Goss’s bacterial wilt pathogen, Clavibacter nebraskensis, of corn is a candidate A1 quarantine organism; and its recent re-emergence and spread in the USA and Canada is a potential biothreat to the crop. We developed and tested an amplicon-based Nanopore detection system for C. nebraskensis (Cn), targeting a purine permease gene. The sensitivit...

The Gram-positive bacterium Clavibacter nebraskensis (Cn) causes Goss’s wilt and leaf blight on corn in the North American Central Plains with yield losses as high as 30%. Cn strains vary in aggressiveness on corn, with highly aggressive strains causing much more serious symptoms and damage to crops. Since Cn inhabits the host xylem, we investigate...

Reactive oxygen species (ROS) represent one of the first lines of plants’ biochemical defense against pathogens. Plants’ respiratory burst oxidase homologs (RBOHs) produce ROS as by-products in several cellular compartments. In potato tubers, Solanum tuberosum respiratory burst oxidase homolog (StRBOHs) are involved in suberization and healing of w...

Soybean plants showing symptoms of root rot were collected from fields in Manitoba, Canada, in 2017, to determine the causal agent of the disease. Of 240 isolated strains, including some known as root rot pathogens, five were identified as Fusarium sporotrichioides Sherb. based on morphological characteristics. All five isolates were pathogenic whe...

This study examined the expression patterns of antioxidative genes and the activity of the corresponding enzymes in the excess moisture-stressed seedlings of soybean in response to seed treatment with polyamines, spermine (Spm) and spermidine (Spd). At the 4 day after planting (DAP) stage, the excess moisture impaired the embryo axis growth, and th...

To determine the beneficial effect of the combination of phosphite (Phi) and Streptomyces hygroscopicus (S11) on soybean plants infected by Phytophthora sojae, soybean seeds were pre-treated with a suspension of S11, the leaves were sprayed with Phi and the roots were subsequently inoculated with P. sojae zoospores. Seedling growth and colonization...

The fungus Pyrenophora tritici-repentis (Ptr) causes tan spot, a destructive foliar wheat disease worldwide. Eight races of Ptr have been identified based on their ability to produce combinations of three necrotrophic effectors: Ptr ToxA, Ptr ToxB and Ptr ToxC. In this study, the complete haploid asexual genomes 37 isolates representing all known r...

Main conclusion Suppression of the maize phytoglobin ZmPgb1.1 enhances tolerance against Clavibacter nebraskensis by promoting hypersensitive response mechanisms mediated by ethylene and reactive oxygen species. Abstract Suppression of the maize phytoglobin, ZmPgb1.1, reduced lesion size and disease severity in leaves following inoculation with Cl...

Fusarium graminearum is a toxigenic plant pathogen that causes Fusarium head blight (FHB) disease on cereal crops. It has recently shown to have cross-pathogenicity on noncereals (i.e., Fusarium root rot [FRR] on soybean) in Canada and elsewhere. Specific detection and differentiation of this potent toxigenic, trichothecene-producing pathogen among...

Fusarium graminearum is a toxigenic plant pathogen that causes Fusarium head blight (FHB) disease on cereal crops. It has recently shown to have cross-pathogenicity on noncereals (i.e., Fusarium root rot [FRR] on soybean) in Canada and elsewhere. Specific detection and differentiation of this potent toxigenic, trichothecene-producing pathogen among...

The phytopathogenic fungus Leptosphaeria maculans causes the blackleg disease on Brassica napus, resulting in severe loss of rapeseed production. Breeding of resistant cultivars containing race-specific resistance genes is provably effective to combat this disease. While two allelic resistance genes LepR3 and Rlm2 recognizing L. maculans avirulence...

Our study investigated disease resistance in the B. napus-L. maculans pathosystem using a combination of laser microdissection, dual RNA sequencing, and physiological validations of large-scale gene sets. The use of laser microdissection improved pathogen detection and identified putative L. maculans effectors and lytic enzymes operative during hos...

Late blight has been an annual disease issue for both potato and tomato crops in Canada in recent years. Plant tissue samples infected with the late blight pathogen collected in Canada from 2015–2017 have yielded multiple clonal genotypes of Phytophthora infestans (Mont.) de Bary that varied by production region. Pathogen isolates collected from Br...

One of the drawbacks of conducting research on Goss's bacterial wilt and leaf blight disease, caused by the bacterium Clavibacter nebraskensis (Cn) on corn (Zea mays L.), is the lack of standardized and validated inoculation and disease assessment methods. Here we report foliar and root inoculation techniques with a standardized scale for reliable...

Goss’s bacterial wilt and leaf blight, caused by Clavibacter nebraskensis (syn. C. michiganensis subsp. nebraskensis), is a serious disease of corn. It is not new to North America, but in 2006, the number of outbreaks increased and the pathogen was reported in areas of the USA and Canada where it had not previously been found. The disease is increa...

In 2017, soybean plants (cv. 24-10RY, R4 growth stage) with poor standing, stunting, and leaf chlorosis were collected at Carman, Manitoba. They had few nitrogen fixing nodules and lateral roots left on the root system, reddish brown-to-black lesions on tap and lateral roots. Roots and lower stems had cortical decay symptoms when split in half. Roo...

One hundred bacteria, isolated from rhizospheric soil and rhizoplane of healthy soybean plants, were assayed for antifungal activity against six Phytophthora sojae isolates. Nine of the tested bacteria inhibited the hyphal growth of P. sojae in vitro. They were subsequently evaluated for their in vitro traits and identified using the 16S rRNA gene...

Fusarium is a potent plant pathogen that causes several economically important diseases such as Fusarium head blight (FHB) in cereals. F. graminearum species complex (FGSC) has been recently reported as a major necrotrophic pathogen of soybean causing seed decay, pre- and post-emergence damping-off, pod blight and root rot in Canada and other regio...

Considering the high incidence of white mold caused by Sclerotinia sclerotiorum in a variety of field crops and vegetables, different control strategies are needed to keep the disease under economical threshold. This study assessed the effect of foliar application of a calcium formulation on disease symptoms, oxalic acid production, and on the oxid...

In the aspen-grassland ecotone of Riding Mountain, Manitoba, lightly browsed vigorous clones of trembling aspen (Populus tremuloides Michx.) occur in close proximity to heavily browsed dieback clones. This study examines whether intraspecific variation in the production of phenolic glycosides is correlated with this strong dichotomy in clonal vigor...

This study aimed to dissect the function of the Isochorismatase Hydrolase (ICSH1) gene in Verticillium dahliae’s pathogenesis on potato. VdICSH1 was up-regulated in V. dahliae after induction with extracts from potato tissues. Its expression increased more in response to root extracts than to leaf and stem extracts. However, such expression in resp...

Pathogenicity of icsh1 mutant on susceptible sunflower line IS8048. Roots of the susceptible sunflower line IS8048 were washed and placed in a conidial suspension of V. dahliae. The percentage of infection, disease severity and plant height were recorded every week. The vascular discoloration of the stem cross-sections were rated at 8 weeks after i...

Amplification of V. dahliae ICSH1 in all potato detached leaves’ treatments at 1 DAI. Kennebec potato detached leaves from 4-week-old plants were placed in conidial suspensions of the V. dahliae highly aggressive isolate Vd1396-9, the weakly aggressive isolate Vs06-07, or sterilized distilled water as a control treatment. (A) Amplification of VdICS...

Pathogenicity of the icsh1 mutant on susceptible tomato variety Bonny Best. Roots of the susceptible tomato variety Bonny Best, were washed and placed in a conidial suspension of V. dahliae. The percentage of infection, disease severity and plant height were recorded for each week after inoculation with icsh1-2-3-1 or icsh1-2-12-1; ectopic control:...

Expression of isochorismatase family members in the V. dahliae icsh1 mutant and wild type strain Vd1396-9 under elicitation with different potato tissue extracts. Verticillium dahliae wild type strain Vd1396-9 and icsh1-2-12-1 were induced in liquid media by different potato tissue extracts. Sterilized distilled water was used as a control treatmen...

Bacterial blight (BB) is caused by Xanthomonas oryzae pv. oryzae (Xoo), a most destructive disease of rice, mostly in Asia, including Bangladesh. Altogether 96 isolates of Xoo were collected from 19 rice-growing districts of Bangladesh in both the rain-fed and irrigated seasons of 2014 to assess their pathotypic and genetic variation. Pathotypic an...

The re-emergence of the Goss's bacterial wilt and blight disease in corn in the U.S.A. and Canada has prompted investigative research to better understand the genome organization. In this study, we generated a draft genome sequence of Cmn strain DOAB 395 and performed genome/proteome analysis of Cmn strains isolated in 2014 (DOAB 397 and DOAB 395)...

Glucosinolates (GSLs) are sulfur-and nitrogen-rich plant secondary metabolites biosynthesized in plant species belonging to the order Brassi­cales. In this study, using recombinant inbred lines (RILs) developed from a cross between Chinese cabbage [Brassica rapa L. subsp. chinensis (L.) Hanelt and subsp. pekinensis (Lour.) Hanelt] and yellow sarson...

Glucosinolates are a group of endogenous secondary metabolites commonly found in Brassica plants. Oilseed rape (Brasscia napus L.) contains toxic glucosinolates in its otherwise high quality meal. Molecular breeding has many advantages over traditional breeding and may provide the solution to further decrease glucosinolate content and/or optimize g...

1-Deoxy-d-xylulose 5-phosphate synthase (DXS) catalyzes the initial step of the plastidial 2C-methyl-d-erythritol-4-phosphate (DOXP-MEP) pathway involved in isoprenoid biosynthesis. In this study, we cloned the complete cDNA of potato DXS gene that was designated StDXS1. StDXS1 cDNA encodes for 719 amino acid residues, with MW of 77.8 kDa, and is p...

Sclerotinia sclerotiorum (Lib.) de Bary is a fungal plant that causes serious losses in important crops. This study examined the expression of selected defense-related genes in the isoflavonoids pathway after soybean inoculation with two Sclerotinia isolates possessing different levels of aggressiveness (SSPetri, highly aggressive and SS18, weakly...

Sclerotinia sclerotiorum (Lib.) de Bary is a fungal plant that causes serious losses in important crops. This study examined the expression of selected defense-related genes in the isoflavonoids pathway after soybean inoculation with two Sclerotinia isolates possessing different levels of aggressiveness (SSPetri, highly aggressive and SS18, weakly...

Hairy vetch (Vicia villosa Roth.) has been recognized as a good candidate for weed suppressive mulch in organic no-till cropping systems. In our study, the allelopathic potential of hairy vetch, fall rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) (extracted species) were evaluated at both vegetative and reproductive developmental s...

At the request of the authors, PLOS Pathogens is retracting this publication following an investigation into concerns about the origin and assembly of Figure 6 and a mounting mistake in Figure 1B. The Northern blot depicted in Figure 6 contains several band duplications affecting the panels labelled 'IP@HA' and 'total RNA'. The figure was provided...

In 2014, the pathogen Clavibacter michiganensis subsp. nebraskensis was isolated from symptomatic corn leaves in Manitoba, Canada. We report the draft genome sequence of C. michiganensis subsp. nebraskensis DOAB 397, consisting of 3.059 Mb with 73.0% G+C content, 2,922 predicted protein-coding sequences, 45 tRNAs, 3 rRNAs, and 37 pseudogenes. Copyr...

We previously identified rutin as part of potato root responses to its pathogen Verticillium dahliae. Rutin was directly toxic to the pathogen at doses greater than 160 μM, a threshold below which many V. dahliae pathogenicity-related genes were up-regulated. We identified and characterized a cupin domain-containing protein (VdQase) with a dioxygen...

The late blight pathogen (Phytophthora infestans) continues to cause major losses on potato and tomato in Canada and worldwide. An increased diversity of P. infestans and dramatic shifts in pathogen populations have occurred in Canada in recent years. In 2011, a survey identified different genotypes of P. infestans in Canada, including the new US-2...

Verticillium dahliae is a pathogen causing vascular wilts in a broad range of plant species. The production of cell wall degrading enzymes (CWDE) is one of the pathogenicity factors contributing to this disease. The expression of eight CWDE genes was estimated in 15 V. dahliae isolates with different hosts of origin and aggressiveness levels. The t...

Plant NADPH oxidases are key regulators of plant-microbe interactions and reactive oxygen species (ROS) are essential to plant defences against pathogens. A significant part in the role played by ROS has been ascribed to plant respiratory burst oxidase homologs (RBOHs). In potato (Solanum tuberosum), where RBOHs were previously shown to be involved...

Verticillium wilt is caused mainly by Verticillium dahliae Kleb. and is a constraint for growers of many economic crops and ornamental plant species. Disease control necessitates the use of multiple methods usually coordinated as part of a disease management strategy. Unlike foliar diseases, much information is lacking for knowledge-based strategie...

Since 2006, verticillium wilt of olive induced by Verticillium dahliae has caused considerable economic losses in olive orchards in Tunisia. Using virulence tests, Vegetative Compatibility Grouping (VCG) and Amplified Fragment Length Polymorphism (AFLP) analyses, we investigated the genetic structure of V. dahliae isolates collected from different...

Forty-two isolates of Verticillium dahliae were recovered from stem and root samples of olive trees showing symptoms of verticillium wilt in various olive-growing regions in Tunisia. Each isolate was identified based on microscopic observations of morphological and cultural characteristics, pathogenicity tests, as well as PCR amplification using Vd...

Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens that threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant pathogenic oomycete species based on scientific and economic importance. In total, we received 263 votes from 62 scientists in 15...

Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens which threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant-pathogenic oomycete species based on scientific and economic importance. In total, we received 263 votes from 62 scientists in 15...

In cereals, ADP-glucose transporter protein plays an important role in starch biosynthesis. It acts as a main gate for the transport of ADP-glucose, the main precursor for starch biosynthesis during grain filling, from the cytosol into the amyloplasts of endospermic cells. In this study, we have shed some light on the molecular and biochemical char...

Late blight, caused by Phytophthora infestans, is a devastating disease of potatoes and tomatoes that causes significant crop losses worldwide. Late blight diversity has been increasing since 2009 in many areas of Canada on both potatoes and tomatoes. Although the US-8 genotype of P. infestans has dominated pathogen populations in much of Canada fo...