In vivo-Untersuchungen zur Entstehung und Funktion der Chlamydosporen von Botrytis cinerea Pers. am Wirt-Parasit-System Fuchsia hybrida – B. cinerea

In vivo-investigations on the formation and function of chlamydospores of Botrytis cinerea Pers. in the host-parasite-system Fuchsia hybrida–B. cinerea On naturally with Botrytis cinerea Pers. infected and artificially inoculated outdoor- and greenhouse-plants of Fuchsia hybrida the extra- and intramatrical formation of the B. cinerea- chlamydospores was investigated. The chlamydospores served 1. as structures of survival, which were tested with regard to their tolerance of drought, nutrient- and oxygen-deficiency, attack by bacteria and pH-requirements. 2. The chlamydospores represented dispersal units, which were capable of germination. 3. The chlamydospores could function as structures of infection, because after chlamydospore germination the outgrowing mycelium – either directly or after production of macroconidia – could serve as secondary inoculum and start new infections.     

Kugelige, umhüllte Mikrokonidien-Aggregate als Überdauerungs- und Verbreitungseinheiten von Botrytis cinerea Pers.

Spherical, coated microconidia-aggregates as survival and dispersal units of Botrytis cinerea Pers. As a reaction to longer lasting unfavourable growth conditions Botrytis cinerea is able to form spherical microconidia-aggregates enclosed in a protective coat. Genesis, structure and occurrence of these so far unknown microconidia-aggregates are described and their function as survival and dispersal units of the fungus is discussed.     

Resistenz verschiedener Kultur- und Wildtomatenpflanzen (Lycopersicon spp.) gegenüber Botrytis cinerea Pers.

Resistance of different cultivated and wild tomato plants (Lycopersicon spp.) to Botrytis cinerea Pers. 20 provenances of different cultivated and wild tomato plants (Lycopersicon spp.) were screened for resistance to Botrytis cinerea Pers. using an in vitro-leaf necrosis test. The Botrytis resistance decreased with increasing age of the leaves corresponding to their insertion height (relative youth resistance respectively senescence susceptibility). The 6 B. cinerea-isolates used for inoculation differed significantly in virulence. With increasing inoculum age a virulence reduction of the various B. cinerea-isolates occurred. Within the investigated test plant collection 2 wild species –L. columbianum and L. hirsutum– proved to be resistant in each stage of development to all B. cinerea-isolates and additionally showed field resistance.     

Einfluß von Tricyclazol auf die Entwicklung und Melaningehalte der Sklerotien von Botrytis cinerea

Effect of tricyclazole on production and melanin contents of sclerotia of Botrytis cinerea Tricyclazole retarded production of sclerotia of Botrytis cinerea on agar medium more severely than mycelium growth. At a concentration range (50–200 mg/l) that did not control Botrytis on grape leaves, sclerotia production was significantly reduced. There was a negative relation between the bleaching duration of sclerotia and the tricyclazole concentrations in the medium on which they were formed. Light microscopical studies showed that sclerotia from tricyclazole-containing medium contained a significantly poorer developed outer melanin layer than that from the control medium. Ultrastructural studies with 5 days old untreated sclerotia revealed intense electron impermeable deposits in the intercellular spaces and a small electron dense layer in the outer cell walls, on the other hand treated sclerotia of the same age showed only sporadic small pigmented deposits between the cells and the pigmentation of the outer cell wall was absent.     

Endogene Hyphen bei Botrytis cinerea Pers.

Endohyphae in Botrytis cinerea Pers. Genesis, following differentiation and significance for pathogenesis The formation of endohyphae (secondary hyphae) in different cell types of Botrytis cinerea Pers. (6 isolates) is described. The following differentiation possibilities of these endohyphae within and—after egress—outside their cells of origin are presented. The influence of external factors (substrate, temperature, humidity, O₂-concentration) on these processes is considered. The significance of the endohyphae for pathogenesis is mainly due to their direct infectivity as well as the ability to develop normal mycelium.     

Über das Gebiss der Acanthodier und Placodermen

In their dentition, acanthodians and placoderms differ from other fishes by the ontogenetie development and replacement of their teeth and by the histology of the functional elements (teeth, cutting edges of the jaws). In some cases special diets are indicated. In general, however, their dentition seems to have been less effective than that of elasmobranchs and teleostomes. This fact may partly account for their early extinction.
Die Eigenart des Gebisses der Aoanthodier und Placodermen inbezug auf die Zahnbildung (Ontogenese), den Zahnersatz und den histologischen Bau der funktionalen Elemente (Zähne, Schneidekanten des Kieferknochens) wird dargestellt. Aus dem Bau des Gebisses läßt sich die Nahrung dieser Tiere teilweise erschließen. Das eigenartige Gebiß verursaehte vermutlich eine Konkurrenzunterlegenheit beim Nahrungserwerb gegenüber den Elasmobranchiern und Teleostomen, vielleicht einer der Gründe, der zum frühen Aussterben der Acanthodier und Placodermen führte.     

Action Spectrum for Photosporogenesis in Botrytis cinerea Pers. ex Fr

An action spectrum for photoinduced conidium formation in the fungus Botrytis cinerea Pers. ex Fr. was determined by exposing colonies to monochromatic radiation obtained from a diffraction grating monochromator. Wavelengths longer than 355 nm were ineffective even after exposures of 8 hours at intensities of 4,068 to 8,276 erg per cm² per second. Colonies were exposed at 22.5 C from 226 to 355 nm at about 5 nm intervals. Three prominent peaks of effectiveness occurred at about 231, 268, and 283 nm, and there was also a minor peak at about 303 nm. The most effective wavelength for inducing sporulation was 231 nm; it was 25% more effective than the second most effective wavelength (283 nm).