A necrosis at the tip of cones was observed on hop (Humulus lupulus), cultivar "Nugget", grown in Oregon in the early 1990's. Fusarium sambucinum and F. avenaceum were recovered from symptomatic cones in 1998 and preliminary inoculation experiments suggested both Fusarium species could cause hop cone necrosis. Studies were carried out to (1) examine pathogenicity and demonstrate Koch's postulates for hop cone tip blight using isolates of F. avenaceum and F. sambucinum obtained from hop cones; (2) examine isolates of F. avenaceum and F. sambucinum derived from other diseased plant hosts, and other Fusarium species derived from hop cones, for ability to cause cone necrosis; and (3) survey commercial fields to determine Fusarium populations on 'Nugget' cone parts. Isolates ofF. avenaceum and F. sambucinum recovered from diseased hop cones were used for pathogenicity experiments. In addition, cone inoculations were done with single isolates of F. avenaceum and F. sambucinum from diseased sweet corn roots, one isolate of F. sambucinum recovered from a diseased potato tuber, individual isolates of F. equiseti and F. oxysporum from hop cones. Cones of two hop cultivars, 'Nugget' and 'Willamette', were collected from three different farms on three sampling dates and inoculated with spore suspensions of hop-derived F. avenaceum and F. sambucinum at concentrations of 10��, 1O���, and 10��� conidia/ml to examine dosage effects. Necrosis was evaluated 2, 4, 6, and 8 days after inoculation. Percent cone necrosis decreased as inoculum concentration of either F. avenaceum or F. sambucinum decreased, and was lowest on water-treated cones, for all three sampling dates. The respective Fusarium species were recovered from symptomatic cones. Cone necrosis developed following cone inoculation with F. avenaceum or F. sambucinum from potato or corn. Hop cones inoculated with F. equiseti or F. oxysporum also developed necrosis, but at relatively lower levels compared to the other Fusarium species used for inoculations. For the surveys in commercial hop fields, burr and cone material were collected on five different dates. Fusarium sambucinum was recovered most frequently, but F. avenaceum was also found. Both Fusarium species were recovered from asymptomatic burr and cone materials throughout the growing season. In general, Fusarium species, F. equiseti, F. oxysporum, F. culmorum, F. solani, plus F. avenaceum and F. sambucinum were found more frequently early in the season on stigmatic tissue, and Fusarium recovery decreased as the season progressed. Fusarium prolferatum and F. monilforme were recovered rarely. / Graduation date: 2004

Most plant oxylipins, a large class of diverse oxygenated polyunsaturated fatty acids and their derivatives, are produced through the lipoxygenase (LOX) pathway. Recent progress in dicots has highlighted the biological roles of oxylipins in plant defense responses to pathogens and pests. In contrast, the physiological function of LOXs and their metabolites in monocots is poorly understood. We cloned and characterized three maize LOXs ZmLOX10 ZmLOX11 and ZmLOX12. Both ZmLOX10 and ZmLOX11 apeared to be 13-LOX, whereas ZmLOX12 is a unique 9-LOX. Whereas leaf was the preferential site of ZmLOX10 expression, ZmLOX11 was strongly expressed in silks. Induction of these ZmLOX10 and ZmLOX12 by wounding and defense-related compounds suggested their role in plant resistance mechanisms against pests and pathogens. Abscisic acid, however, was the only inducer of ZmLOX11 in leaves. Higher increase in ZmLOX10 transcripts in maize infected by fungus Cochliobolus carbonum implicated this gene in resistance responses to necrotrophic pathogens. In addition, ZmLOX10 was shown to be the first reported LOX to be regulated by a circadian clock. It was found that ZmLOX10 was also inducible by low temperatures. Phenotypical studies of wild type and mutant near isogenic lines showed that expression of ZmLOX12, specific to underground organs, was required for pathogenesis of F. verticillioides on maize mesocotyls.

Environmental hazards and health problems due to the application of chemical pesticides in agricultural sectors incite huge public concerns. Therefore, one of the better solutions is through introduction of biological control means to manage the outbreaks of plant diseases. To date, only small numbers of beneficial microorganisms - belonging to the category of hyperparasitic or mycoparasitic fungi have proven to keep plants or protect crops from plant pathogen infection. The objective of this study was to characterize a group of <i>Fusarium</i>-associated melanosporaceous biotrophic mycoparasitic fungal isolates, which were identified and pre-selected by Dr. Vladimir Vujanovic and deposited in the Saskatchewan Microbial Collection and Database (SMCD). Particular objectives were to examine spore germination of a biotrophic mycoparasite, to test effects of this fungus on seed germinations, to study interactions between the mycoparasite and Fusarium hosts, and to investigate relationships between the mycoparasite-the <i>Fusarium</i> host-wheat root under controlled conditions in the university Phytotron facilities.<p> Information related to this group of fungi is relatively limited. In order to characterize potential biotrophic mycoparasitic fungal isolate(s), molecular and microscopy methods were performed to accomplish taxonomical, phylogenetical and morphological studies. Since, spore germination is a very crucial stage in fungal life cycle and growth, ascospores (sexual spores) of the biotrophic mycoparasite were isolated from a fungal colony. These spores were inoculated on media supplemented with different <i>Fusarium</i>-filtrates or suspended in different <i>Fusarium</i>-filtrates to examine spore germination rates and growth patterns. Together with other mycoparasitic fungi, this biotrophic mycoparasite was inoculated on spring wheat seeds, to test effects of these fungal inoculants on seedlings growth using <i>in vitro</i> assays. Dual-culture, slide culture, and microscopy approaches were carried out to elucidate intimate and special relationship between the biotrophic mycoparasite and <i>Fusarium</i>-hosts. In order to study tritrophic interactions (biotrophic mycoparasite-<i>Fusarium</i> host-wheat root), spring wheat was grown in the phytotron with different treatments of fungal inoculations. Wheat roots were then subjected to genus-specific quantitative real-time PCR analyses.<p> One melanosporaceous biotrophic mycoparasitic strain was identified as a new species in the genus <i>Sphaerodes</i>. This biotrophic mycoparasite was isolated from <i>Fusarium</i>-infected fields in Saskatchewan and Quebec, and named <i>Sphaerodes mycoparasitica</i>. Germination of <i>S. mycoparasitica</i> sexual spores was improved when treated with filtrates or extracellular extracts from the <i>Fusarium</i>-host as compared to <i>Fusarium</i>-non-host filtrates. No pathogenic effects on wheat seeds were observed when inoculated with <i>S. mycoparasitica</i>. Furthermore, seedlings growth was enhanced with this biotrophic mycoparasite compared to other mycoparasitic fungi. Later, this biotrophic mycoparasitic strain was found to establish biotrophic fusion and haustorial contact relations with <i>F. avenaceum, F. oxysporum</i>, and two F. graminearum chemotypes. Since, 3-Acetyldeoxynivalenol-producing <i>F. graminearum</i> is one of the most highly toxigenic and aggressive wheat pathogens in Saskatchewan and North America, therefore, this pathogen strain was chosen for tritrophic interaction study. Under controlled conditions in the phytotron, <i>S. mycoparasitica</i> improved seedlings growth when these were challenged with <i>F. graminearum</i> as compared to seedlings only inoculated with the <i>Fusarium</i> pathogen. In conclusion, S. mycoparasitica could be a potential candidate for biological control of <i>Fusarium</i> diseases in wheat.

Environmental hazards and health problems due to the application of chemical pesticides in agricultural sectors incite huge public concerns. Therefore, one of the better solutions is through introduction of biological control means to manage the outbreaks of plant diseases. To date, only small numbers of beneficial microorganisms - belonging to the category of hyperparasitic or mycoparasitic fungi have proven to keep plants or protect crops from plant pathogen infection. The objective of this study was to characterize a group of <i>Fusarium</i>-associated melanosporaceous biotrophic mycoparasitic fungal isolates, which were identified and pre-selected by Dr. Vladimir Vujanovic and deposited in the Saskatchewan Microbial Collection and Database (SMCD). Particular objectives were to examine spore germination of a biotrophic mycoparasite, to test effects of this fungus on seed germinations, to study interactions between the mycoparasite and Fusarium hosts, and to investigate relationships between the mycoparasite-the <i>Fusarium</i> host-wheat root under controlled conditions in the university Phytotron facilities.<p> Information related to this group of fungi is relatively limited. In order to characterize potential biotrophic mycoparasitic fungal isolate(s), molecular and microscopy methods were performed to accomplish taxonomical, phylogenetical and morphological studies. Since, spore germination is a very crucial stage in fungal life cycle and growth, ascospores (sexual spores) of the biotrophic mycoparasite were isolated from a fungal colony. These spores were inoculated on media supplemented with different <i>Fusarium</i>-filtrates or suspended in different <i>Fusarium</i>-filtrates to examine spore germination rates and growth patterns. Together with other mycoparasitic fungi, this biotrophic mycoparasite was inoculated on spring wheat seeds, to test effects of these fungal inoculants on seedlings growth using <i>in vitro</i> assays. Dual-culture, slide culture, and microscopy approaches were carried out to elucidate intimate and special relationship between the biotrophic mycoparasite and <i>Fusarium</i>-hosts. In order to study tritrophic interactions (biotrophic mycoparasite-<i>Fusarium</i> host-wheat root), spring wheat was grown in the phytotron with different treatments of fungal inoculations. Wheat roots were then subjected to genus-specific quantitative real-time PCR analyses.<p> One melanosporaceous biotrophic mycoparasitic strain was identified as a new species in the genus <i>Sphaerodes</i>. This biotrophic mycoparasite was isolated from <i>Fusarium</i>-infected fields in Saskatchewan and Quebec, and named <i>Sphaerodes mycoparasitica</i>. Germination of <i>S. mycoparasitica</i> sexual spores was improved when treated with filtrates or extracellular extracts from the <i>Fusarium</i>-host as compared to <i>Fusarium</i>-non-host filtrates. No pathogenic effects on wheat seeds were observed when inoculated with <i>S. mycoparasitica</i>. Furthermore, seedlings growth was enhanced with this biotrophic mycoparasite compared to other mycoparasitic fungi. Later, this biotrophic mycoparasitic strain was found to establish biotrophic fusion and haustorial contact relations with <i>F. avenaceum, F. oxysporum</i>, and two F. graminearum chemotypes. Since, 3-Acetyldeoxynivalenol-producing <i>F. graminearum</i> is one of the most highly toxigenic and aggressive wheat pathogens in Saskatchewan and North America, therefore, this pathogen strain was chosen for tritrophic interaction study. Under controlled conditions in the phytotron, <i>S. mycoparasitica</i> improved seedlings growth when these were challenged with <i>F. graminearum</i> as compared to seedlings only inoculated with the <i>Fusarium</i> pathogen. In conclusion, S. mycoparasitica could be a potential candidate for biological control of <i>Fusarium</i> diseases in wheat.

Most plant oxylipins, a large class of diverse oxygenated polyunsaturated fatty acids and their derivatives, are produced through the lipoxygenase (LOX) pathway. Recent progress in dicots has highlighted the biological roles of oxylipins in plant defense responses to pathogens and pests. In contrast, the physiological function of LOXs and their metabolites in monocots is poorly understood. We cloned and characterized three maize LOXs ZmLOX10 ZmLOX11 and ZmLOX12. Both ZmLOX10 and ZmLOX11 apeared to be 13-LOX, whereas ZmLOX12 is a unique 9-LOX. Whereas leaf was the preferential site of ZmLOX10 expression, ZmLOX11 was strongly expressed in silks. Induction of these ZmLOX10 and ZmLOX12 by wounding and defense-related compounds suggested their role in plant resistance mechanisms against pests and pathogens. Abscisic acid, however, was the only inducer of ZmLOX11 in leaves. Higher increase in ZmLOX10 transcripts in maize infected by fungus Cochliobolus carbonum implicated this gene in resistance responses to necrotrophic pathogens. In addition, ZmLOX10 was shown to be the first reported LOX to be regulated by a circadian clock. It was found that ZmLOX10 was also inducible by low temperatures. Phenotypical studies of wild type and mutant near isogenic lines showed that expression of ZmLOX12, specific to underground organs, was required for pathogenesis of F. verticillioides on maize mesocotyls.

Benzoin is an important a-hydroxy ketone which can be used as chiral intermediate for the synthesis of several drugs. In this study, it was aimed to synthesize this compound by high stereoslectivity and yield by the use of fungal bioconversions. For this purpose, whole cells of four different Fusarium spp. (F. anguoides, F. roseum, F. solanii, F.bulbigenum) were used for reduction of readily available achiral compound benzil. The reaction conditions were optimized as glucose peptone broth consisting of 30g/L glucose and 10 g/L peptone, inoculum size as 20 mg/L and substrate concentration as 200 mg/L. A complete set of derivatives substituted with electron donating and electron withdrawing groups of the benzils were also reduced to the corresponding benzoin derivatives with the same optimized condition with up to 98% ee.

In questa tesi di dottorato sono stati indagati i punti critici legati ai fattori biotici e abiotici che possono influenzare la crescita del fungo Fusarium verticillioides, produttore di fumonisine in mais. le fumonisine sono metaboliti secondari prodotte da funghi appartenenti al genere Fusarium e sono state classificate come possibili cancerogene per l’uomo e per gli animali. Gli argomenti trattati nei vari capitoli sono stati: parametri ecologici che condizionano la crescita e l’accumulo di fumonisine nelle prime fasi post raccolta e durante lo stoccaggio; relazione che intercorre tra aw, umidita’ relativa e tipo di ibrido; controllo con mezzi chimici e biologici in campo e in vitro su F. verticillioides e A. flavus. / The aim of this work was to collect missing information about critical point related to abiotic and biotic factors that can influence the growth of Fusarium verticillioides in maize and the consequent production of fumonisins in kernels. Fumonisins are secondary metabolites reported as toxigenic in humans and animals. Issues treated are: variables influencing growth and toxin accumulation during post-harvest and storage; the relationship between aw, relative humidity and type of hybrids; chemical and biological control of F. verticillioides e A. flavus in field and in vitro.

No description available.

Consumption of feedstuffs contaminated by Fusarium mycotoxins and the development of equine gastric ulcer syndrome (EGUS) affect the overall health of horses. A study was conducted to determine if feed-borne mycotoxins have an effect on EGUS, and the efficacy of a glucomannan mycotoxin adsorbent (GMA) was determined. Feed intake was decreased with the GMA diet compared to control horses. Body weight, ulcer score and gastrin concentration were unaffected by diet. Some significant changes in blood parameters potentially indicate liver damage and inhibition of protein synthesis. Histological evaluation showed an increase in mononuclear cells in the glandular region of the contaminated group likely indicating signs of gastritis. The incorporation of the GMA may reduce these negative effects on the horse based on our findings. It can be concluded that horses are susceptible to Fusarium mycotoxins with a possible effect on EGUS, as seen in the cells of the gastric glandular mucosa. / Alltech Inc., Nicholasville, Kentucky and OMAFRA

An evaluation of nineteen barley lines using three artificial inoculation methods concluded that spray inoculation was the most reproducible method and provided the greatest discrimination of resistance. Six of the nineteen barley lines were used for proteomic studies to identify defense responses following F. graminearum infection. All lines responded by inducing an oxidative burst and pathogenesis-related proteins. Differences in response magnitude and the proteins activated could be attributed to varying levels of FHB resistance amongst the barley lines. RNA microarray profiling and iTRAQ technology were used to study the interaction between two barley lines under five different treatments testing the effect of the fungus, trichothecene, and their interaction. Resistance was differentiated by the early induction of defense-related genes and the activation of the JA and ethylene defense pathways in Chevron, compared to the induction of a less efficient defense pathway in Stander; observed intra- and inter-cultivar differential responses are discussed. / xvii, 196 leaves : ill. ; 29 cm.