ABSTRACT
Claviceps species are the causal agents of the ubiquitous ergot disease. About thirty-six different filamentous fungi constitute this genus of phytopathogenic ascomycetes. They parasitize more than 600 monocotyledonous plants of the families Poaceae, Juncaceae and Cyperaceae (Bové, 1970), including forage grasses and the leading cereals worldwide: wheat, rice, corn, barley, sorghum, oats, rye, millets (Baum et al., 1992). Being epidemic to a greater extent in semi-arid regions than in temperate zones, ergot is of increasing importance in India and Africa, where pearl millet and sorghum are essential crops (Frederickson et al., 1993). Although the fungi cause harvest losses due to replacement of host ovaries with the parasite’s resting structures, the ergotcalled sclerotia, the main problem is not a severe loss in seed quantity but arises from complete ruin of grain quality due to the alkaloid content of the sclerotia. Admittedly, ergot alkaloids are secondary metabolites of high pharmacological value and are, therefore, produced worldwide on a large scale, nevertheless, these toxins cause highly dangerous or even deadly ergotism when contaminated grains are fed to animals or are consumed by man. These are the reasons for a continuous interest for ages in ergot fungi and their persistent importance (see chapter 1 in this volume), which will remain valid as long as the main ubiquitous nutritional basis to man and herbivorous livestock is concerned. Worldwide reduction in grain yield and quality causes the permanent necessity for an expensive cleaning of attacked cereals to maintain a minimum of purity standard. A contamination of crops with ergots higher than 0.3% by weight spoils the grain even for feeding (Agrios, 1988). Specific measures for reliable control as well as utilization of positive capacities of ergot fungi closely depend on an overall understanding of host-and pathogen biology.
