Plant Pathology Unit

Mobile, Israel

Plant Pathology Unit

Mobile, Israel
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Ismail Y.,University of Montréal | Ismail Y.,Plant Pathology Unit | McCormick S.,U.S. Department of Agriculture | Hijri M.,University of Montréal
PLoS ONE | Year: 2011

Fusarium trichothecenes are fungal toxins that cause disease on infected plants and, more importantly, health problems for humans and animals that consume infected fruits or vegetables. Unfortunately, there are few methods for controlling mycotoxin production by fungal pathogens. In this study, we isolated and characterized sixteen Fusarium strains from naturally infected potato plants in the field. Pathogenicity tests were carried out in the greenhouse to evaluate the virulence of the strains on potato plants as well as their trichothecene production capacity, and the most aggressive strain was selected for further studies. This strain, identified as F. sambucinum, was used to determine if trichothecene gene expression was affected by the symbiotic Arbuscular mycorrhizal fungus (AMF) Glomus irregulare. AMF form symbioses with plant roots, in particular by improving their mineral nutrient uptake and protecting plants against soil-borne pathogens. We found that that G. irregulare significantly inhibits F. sambucinum growth. We also found, using RT-PCR assays to assess the relative expression of trichothecene genes, that in the presence of the AMF G. irregulare, F. sambucinum genes TRI5 and TRI6 were up-regulated, while TRI4, TRI13 and TRI101 were down-regulated. We conclude that AMF can modulate mycotoxin gene expression by a plant fungal pathogen. This previously undescribed effect may be an important mechanism for biological control and has fascinating implications for advancing our knowledge of plant-microbe interactions and controlling plant pathogens.

Alananbeh K.M.,North Dakota State University | Alananbeh K.M.,Taibah University | Lahkim L.T.,Plant Pathology Unit | Gudmestad N.C.,North Dakota State University
American Journal of Potato Research | Year: 2014

The present study tested the hypothesis that the global C. coccodes population is genetically differentiated by region of origin. A total of 855 isolates, originating from North America (475), Europe (147), Israel (66), Australia (86), South Africa (14) and additional testers (67), which previously were assigned to VCGs (21 international VCGs) were examined for their genetic diversity. Using the previously assigned North American VCGs as the leading sub-population, and with the aid of amplified fragment length polymorphism (AFLP) markers, the isolates were grouped into five VCG/AFLP sub-populations (1, 2, 3, 4/5 and 6/7). These were distributed between two phylogeny clusters, designated Cc-A and Cc-B. Cluster Cc-A was unique and composed of isolates from VCG/AFLP6/7 only, whereas cluster Cc-B was composed of the remaining four VCG/AFLP sub-populations, which was further divided into 17 sub-clusters. VCG/AFLP4/5 was the most common VCG globally, followed by VCG/AFLP2. Most of the variation among the four geographic regions originated from the within population differentiation (84 %). It is concluded from these studies that the global population of C. coccodes exists as one large population with five main VCG/AFLPs worldwide and that they are probably of the same origin, however, geographic isolation caused these populations to differentiate and form distinct sub-clusters. © 2013 Potato Association of America.

Perez S.,Agricultural University of Havana | Ahmed A.I.S.,Plant Pathology Unit | Cabezas D.,Agricultural University of Havana
Biotecnologia Aplicada | Year: 2013

Two different Pb concentrations (5 and 10 mg/kg of PbAc2) were used to study the response of Solanum lycopersicum L. cv. Micro-Tom (MT) plants in two vegetative growth phases. Two genes that have been previously reported to be heavy metal inducible genes (superoxide dismutase, SOD, EC; and isofl avone reductase, IFR; EC and another one putatively interesting in this fi eld (transcriptionally controlled tumor protein, TCTP) were selected for an expression study using a real time PCR technique. In the fi rst growth phase (germination to fl owering) TCTP was repressed at 10 mg/kg and in the control, SOD expression was low at both concentrations (5 and 10 mg/kg of PbAc2) and IFR was higher at 10 mg/kg PbAc2. In the second phase (fl owering to fructifi cation) three genes were expressed in both concentrations but in the case of TCTP and SOD the expression was higher at 5 mg/kg of PbAc2. SOD and Glutathione reductase (GR; EC were selected for a biochemical study together with the determination of protein concentration using spectrophotometer. SOD was higher at 10 mg/kg PbAc2 showing signifi cant difference with control, and GR had the same behavior but had signifi cant differences with the other two treatments while total proteins were higher for the control showing signifi cant differences at 10 mg/kg of PbAc2. This research suggests that Pb toxicity leads to the induction of key enzymes of antioxidant defense system in tomato plants. © Biotecnología Aplicada 2013.

Ahmed A.I.S.,Plant Pathology Unit | Yadav D.R.,Kangwon National University | Lee Y.S.,Kangwon National University
International Journal of ChemTech Research | Year: 2016

The objective of this study was to evaluate antifungal activity of nickel nanoparticles against Fusarium species as an alternative to existing methods. In this study, nickel nanoparticles at concentrations of 10, 20, 50 and 100 ppm, were evaluated for their antifungal activity on42 isolates of Fusarium belonging to different species isolated from crop field soils of different locations in Korea. The fungal isolates were grown on three different media, potato dextrose agar, corn meal agar and malt extract agar, amended with nickel nanoparticles. The results indicate that nickel nanoparticles at concentrations of 50 and 100 ppm inhibited the mycelial growth of Fusarium isolates investigated. Nickel nanoparticles at a concentration of 100 ppm caused more than 90% inhibition of mycelial growth in six isolates on malt extract agar media. The range of growth inhibition was 24.7-90.2% and 21.67-85.1% at a concentration of 100 ppm on corn meal agar and potato dextrose media, respectively. The light and scanning electronic microscope examinations revealed that the nickel nanoparticles caused damage of mycelia and spores of tested Fusarium species. This study suggests that nickel nanoparticles at high concentration could be used to control Fusarium fungi. However, further studies are needed to assess the effect of nickel nanoparticles on the growth of host plant. © 2016, Sphinx Knowledge House. All rights reserved.

Ismail Y.,University of Montréal | Ismail Y.,Plant Pathology Unit | Hijri M.,University of Montréal
Functional Plant Biology | Year: 2012

Arbuscular mycorrhizal fungi (AMF) are symbiotic, root-inhabiting fungi colonising a wide range of vascular plant species. We previously showed that AMF modulate the expression of mycotoxin genes in Fusarium sambucinum. Here, we tested the hypothesis that AMF may induce defence responses in potato to protect against infection with F. sambucinum. We analysed the response of AMF-colonised potato plants to the pathogenic fungus F. sambucinum by monitoring the expression of defence-related genes ChtA3, gluB, CEVI16, OSM-8e and PR-1. In response to F. sambucinum infection, we found that the AMF treatment upregulated the expression of all defence genes except OSM-8e in potato roots at 72 and 120h post infection (hpi). However, we found variable transcriptional regulation with gluB and CEVI16 in shoots at both times 72 and 120 hpi in AMF-colonisation and infected plants. Overall, differential regulation of defence-related genes in leaf tissues indicate that AMF are a systemic bio-inducer and their effect could extend into non-infected parts. Thus, AMF significantly suppressed disease severity of F. sambucinum on potato plants compared with those infected and non-mycorrhizal plants. Furthermore, the AMF treatment decreased the negative effects of F. sambucinum on biomass and potato tuber production. © 2012 CSIRO.

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