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''Claviceps purpurea'' is an ergot fungus that grows on the ears of rye and related cereal and forage plants. Consumption of grains or seeds contaminated with the survival structure of this fungus, the ergot sclerotium, can cause ergotism in humans and other mammals.〔(ergot ), online medical dictionary〕〔(ergot ), Dorland's Medical Dictionary〕 ''C. purpurea'' most commonly affects outcrossing species such as rye (its most common host), as well as triticale, wheat and barley. It affects oats only rarely. == Life cycle == An ''ergot kernel'' called ''Sclerotium clavus'' develops when a floret of flowering grass or cereal is infected by a ascospore of ''C. purpurea''. The infection process mimics a pollen grain growing into an ovary during fertilization. Because infection requires access of the fungal spore to the stigma, plants infected by ''C. purpurea'' are mainly outcrossing species with open flowers, such as rye (''Secale cereale'') and Alopecurus. The proliferating fungal mycelium then destroys the plant ovary and connects with the vascular bundle originally intended for feeding the developing seed. The first stage of ergot infection manifests itself as a white soft tissue (known as ''Sphacelia segetum'') producing sugary honeydew, which often drops out of the infected grass florets. This honeydew contains millions of asexual spores (conidia) which are dispersed to other florets by insects or rain. Later, the ''Sphacelia segetum'' convert into a hard dry ''Sclerotium clavus'' inside the husk of the floret. At this stage, alkaloids and lipids (e.g. ricinoleic acid) accumulate in the Sclerotium. When a mature ''Sclerotium'' drops to the ground, the fungus remains dormant until proper conditions trigger its fruiting phase (onset of spring, rain period, need of fresh temperatures during winter, etc.). It germinates, forming one or several fruiting bodies with head and stipe, variously colored (resembling a tiny mushroom). In the head, threadlike sexual spores (ascospores) are formed in perithecia, which are ejected simultaneously, when suitable grass hosts are flowering. Ergot infection causes a reduction in the yield and quality of grain and hay produced, and if infected grain or hay is fed to livestock it may cause a disease called ergotism. ''Polistes dorsalis'', a species of social wasps, have been recorded as a vector of the spread of this particular fungus. During their foraging behavior, particles of the fungal conidia get bound to parts of this wasp's body. As ''P. dorsalis'' travels from source to source, it leaves the fungal infection behind. Insects, including flies and moths, have also been shown to carry conidia of ''Claviceps'' species, but if insects play a role in spreading the fungus from infected to healthy plants is unknown. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Claviceps purpurea」の詳細全文を読む スポンサード リンク
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