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Three species of higher algicolous fungi were examined at the autecologica1, cultural, light microscope, and scanning and transmission electron microscope levels. Fungal development and the host-parasite relationship are described for each association. The seasonal occurrence of marine fungi from intertidal populations of Dilsea carnosa, Ascophyllum nodosum and Chondrus crispus was examined at Bembridge, Isle of Wight, UK. A basidiomycete pathogen, Mycaureola dilseae, was found on D. carnosa, and two ascomycetes, Mycosphaerella ascophylli and Lautitia danica, on A. nodosum and C. crispus, respectively. Mycaureola dilseae is host specific and exhibited a limited reproductive cycle with green necrotic lesions and basidiomata observed only during September and October. Mycosphaerella ascophylli is an obligate endophyte of A. nodosum, an association in which the fungal and algal reproductive cycles were found to be synchronous with sporocarps confmed to host receptacles. This fungus is also found in Pelvetia canaliculata. Sporocarps of L. danica were recorded on cystocarpic C. crispus throughout the year, with a higher incidence of the fungus on older fronds. Tetrasporic C. crispus was also infected and in both cases the fungus was confmed to algal reproductive tissues. Mycosphaerella ascophylli was isolated from A. nodosum and P. canaliculata tissues and the anamorph, Septoria ascophylli was induced to sporulate. Growth of M. di/seae from D. carnosa lesions was limited and Lautitia danica could not be isolated from infected C. crispus tissues. Ascospore (L. danica and M. ascophylli) and basidiospore (M. di/seae) cultures did not grow beyond the germ tube phase. Hyphae of M. dilseae grew both inter- and intra-cellularly in D. carnosa. Penetration of algal cells was initially achieved by fme bifurcated penetration hyphae and there is evidence of mechanical pressure and localized enzyme action. The fungus caused a progressive breakdown of algal cell walls and cell contents; particularly evident was the damage to chloroplasts and dissolution of Floridean starch grains. Infection fmally resulted in the formation on necrotic lesions, each surrounded by a ring of basidiomata. Transmission electron microscopy showed the ascus of M. ascophylli to be bitunicate with a thick endoascus and thin ectoascus. Intra-membranous haustoria were occasionally observed in the outer cell wall of A. nodosum and P. canaliculata. Lautitia danica asci were bitunicate and ascospores were covered with a mucilagenous layer. Penetration of host cells caused extensive damage and blackening of host reproductive tissues. The relevance of these results are discussed in relation to algal pathology and marine fungal ultrastructure.

<p>Hydrophobins are a class of small proteins (7-15kDa) found in filamentous fungi and are among the most surface active proteins known today. Because of this they have received attention for different applications, e.g. for the food industry as an alternative in emulsions. The goal of this project was to culture and extract hydrophobins from <em>Trichoderma reesei</em> and characterize it. This was done from a freeze-dried culture of <em>Trichoderma reesei</em>, which was cultured on PDA-plates and in liquid medium with glucose as carbon source. Extraction was made by breaking the cells, mechanically and by sonication, and then by shaking a seperating funnel to create foam from the surface-active proteins. The foam was washed and freeze-dried and the total protein concentration of the freeze-dried substance was determined with Bradford assay and the hydrophpbin was characterized with SDS-PAGE. The culturing of the fungi was successful. The amount of foam created was, however, less than expected. The Bradford assay gave a total protein concentration of 7.5% in the freeze-dried substance, but the SDS-PAGE didn't give any results. The reason for this probably depends on the culturing and the extraction of the hydrophobin. <em>T. reesei</em> hydrophobin HFBI, expressed in glucose containing media, is bound to the mycelium of the fungi and the breaking of the mycelium might not have been enough to release all the protein, which also would explain the small amounts of foam. One way to improve this could be to grow the fungi on lactose instead. This will result in that T. reesei produces HFBII instead, which is mainly released to the surrounding. The conclusion of the project is that the method for culturing and extraction needs to be improved to obtain hydrophobin from <em>T. reesei</em>.</p>

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Alternaria tagetica is capable of producing phytotoxins in vitro. One toxin was identified as zinniol with: bioassays; thin-layer and gas chromatography; staining properties; ultraviolet and mass spectrometry, and nuclear magnetic resonance spectroscopy. The identity of the other toxin(s) has not been established. Symptoms similar to those caused by infection developed on detached marigold leaves treated with either of the toxins or synthetic zinniol. The toxins are not host selective. The distribution of zinniol among Alternaria species was studied. Thirty-one isolates of 10 pathogenic Alternaria spp. were tested for their ability to produce zinniol. Analyses were performed by gas-liquid and thin-layer chromatography. Of the seven pathogenic large-spored, long-beaked species tested A. carthami, A. macrospora, A. porri, A. solani, A. tagetica, and an unnamed isolate from Phaseolus vulgaris pods produced zinniol. A. brassicae, a non-pathogenic isolate of A. zinniae, and three pathogenic species lacking large-spores and long-beaks (A. alternata, A. citri, and A. raphani) did not produce zinniol. The quantity of zinniol produced varied greatly among species, among isolates of a single species, and between trials of the same isolate. All hosts of the Alternaria spp. tested were sensitive to zinniol at 50 to 200 micrograms/ml. Conservation of zinniol in pathogenic large-spored Alternaria spp. may be indicative of its importance in pathogenesis. Light affects the behavior of Alternaria tagetica in vitro and in vivo. In vitro zinniol production occurred only during active fungus growth in the light; in the dark zinniol production occurred primarily after growth stopped. In all filtrates, the quantity of zinniol rapidly declined once zinniol production ceased. Fungus growth was inhibited by both continuous and alternating light and sporulation occurred on one of three test media and only under alternating light. More lesions were produced on inoculated plants kept in dark humidity chambers than in illuminated humidity chambers. Low illuminance was more conducive to lesion development than high illuminance and more lesions developed on plants exposed to low illuminance for 48 hr prior to inoculation than on those exposed to high illuminance. The limitations of studies in which the effect of light has been overlooked are discussed.