Spores germination

Fig. 1.11 Spore germination, outgrowth and division ofthe outgrown cells.

The effect of flavonoids on spore germination and hyphal growth of ecto-mycorrhizal fungi is poorly known. However, several metabolites relea.sed by the plant roots trigger events leading to their infection (44,55). In the saprotrophic phase, spores of several ectomycorrhizal fungi respond to stimulation by abietic acid, the diterpene resin acid, in root exudates (56). 

V. Gianinazzi-Pearson, B. Branzanti, and S. Gianinazzi, In vitro enhancement of spore germination and early hyphal growth of a vesicular-arbuscular mycorrhizal fungus by host root exudates and plant flavonoids. Symbiosis 7 243 (1989). 

N. Fries, K. Serck-Hanssen, L. Hiill-Dimberg, and O. Theander, Abietic acid, an activator of basidio.spore germination in ectoinycorrhizal species of the genus Sidl-liis (Boletaceae). Exp. Mycol. 77 360 (1987). 

Spores germinate in a variety of ways. There is a considerable degree of constancy in the method of spore germination for each species. Lamanna classified the modes of germination as follows ... 

I. Spore germination by shedding of spore coat. Characteristics of this method, are... 

Figure 4.5 Methods of spore germination. From left to right equatorial germination without splitting along transverse axis equatorial germination with splitting along transverse axis polar germination spore germination by comma-shaped expansion.

Macko V (1981) Inhibitors and stimulants of spore germination and infection structure formation in fungi. In Turian G, Holh HR (eds) The fungal spore morphogenetic controls. Academic Press, New York, p 565... 

The whole Cladonia thalli and its derived fraction delay the spore germination and regeneration of new filaments and also inhibit their growth. Some alterations at cell level are the granular appearance and the presence of microvesicles in cytoplasm and the alterations in the shape of chloroplast, which become spherical and bulged. In cultures with whole Cladonia thalli, moss protonemal filaments are significantly shorter than... 

Spore germination and protonemal growth and morphogenesis are therefore, useful systems to test in vitro, with good reproducibility, potential allelochemicals both through direct co-existence test in vitro or using the described bioassays to monitor/guide isolation, purification, characterization of chemical structure of bioactive compounds. 

Condensation of coumaric acid with malonic acid yields the basic chalcone and stilbane skeletons (see Fig. 3.6). Stilbenes are found in most vascular plants, where they exhibit fungicidal and to a lesser extent antibiotic properties. They function as both constitutive and inducible defense substances. Some stilbenes inhibit fungal spore germination and hyphal growth, whereas others are toxic to insects and parasitic nematodes (round-worms). They also possess antifeeding and nematicide properties in mammals. For example, resveratrol (a stilbene in red wine) suppresses tumor formation in mammals. 

Finally, the antifungal properties of a-pinene and limonene, two monoter-penes frequently found in the defensive secretion of Nasutitermes termites, was studied. In vitro assays showed that these molecules reduce spore germination of the fungus Metarhizium anisopliae through direct and indirect (vapor) contact [225]. Moreover, some diterpenes isolated from these insects have also an antibiotic activity on Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis [226]. 

Wound botulism occurs where C. botulinum spores germinate in wound infections and develop into vegetative cells. In such cases, neurotoxin is produced which leads to the onset of neurological symptoms. According to the Centers for Disease Control and Prevention, 23 cases of wound botulism (13.6% of all botulism cases) were reported in 2001 in the U.S. Wound botulism has also been diagnosed after intravenous drug injection (Rundervoort et al., 2003). 

Canned mushrooms were involved in many cases of botulism. It is suggested that Agaricus bisporus may induce C. botulinum spore germination due to oxygen consumption (Sugiyama and Yang, 1975). 

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