Ergot of Rye - I: Introduction and History



Introduction


Ergot of Rye is a plant disease that is caused by the fungus Claviceps purpurea. The so-called ergot that replaces the grain of the rye is a dark, purplish sclerotium (Figs. 1a-b), from which the sexual stage (Fig. 2a-b), of the lifecycle will form after over wintering. The sexual stage consists of stroma in which the asci and ascospores are produced. Although the ergot is far different in appearance than the true grain, its occurrence was so common that it was thought to be part of the rye plant, until the 1850's, when the true nature of the ergot was understood. Although the common name indicates that this fungus is a disease of rye, it also can infect several other grains, with rye being the most common host for this species. It is the ergot stage of the fungus that contains a storehouse of various compounds that have been useful as pharmaceutical drugs as well as mycotoxins that can be fatal when consumed. The proportion of the compounds produced will vary within the species. Thus, the victim that has lived through ergot poisoning once may experience different symptoms if they were unfortunate enough to consume ergot for a second time. This species was also the original source from which LSD was first isolated. It is believed that symptoms of ergotism have been recorded since the middle ages and possibly even as far back as ancient Greece.


There are approximately 35 species of Claviceps, with most occurring on grasses. All species form the sclerotium that is described above, and will form the same types of compounds. Although some research have been carried out in these other species, the bulk of our knowledge and most of our research has been concerned with Ergot of Rye.


Today, we will go over the consequences of consumption of the ergot stage of Claviceps purpurea and describe some of the impact that it has had.