User:Pinof/Essai

Intraspecific variations
Early, scientists have observed Claviceps purpurea on other Poaceae as Secale cereale. 1855, Grandclement described ergot on Triticum aestivum. During more than a century scientists aimed to describe specialized species or specialized varieties inside the species Claviceps purpurea. That's how are created the species
 * Claviceps microcephala Tul. (1853)
 * Claviceps wilsonii Cooke (1884)

Later scientists tried to detemine host varieties as
 * Claviceps purpurea var. agropyri
 * Claviceps purpurea var. purpurea
 * Claviceps purpurea var. spartinae
 * Claviceps purpurea var.wilsonii.

But molecular biology hasn't confirmed this hypothesis but has distinguished three groups differing in their ecological specificity.


 * G1 — land grasses of open meadows and fields;
 * G2 — grasses from moist, forest, and mountain habitats;
 * G3 (C. purpurea var. spartinae) — salt marsh grasses (Spartina, Distichlis).

The criteria to distinguish different groups was the morphology: The shape and the size isn't a good indicator because they strongly depends on the size and shape of the host floret. The size of conidia can be an indication but it is weak and it is is necessary to pay attention to that, due to osmotic pressure, it varies significantly if the spores are observed in honeydew and or in water. The density can be used indeed the group G3 is adapted to float in salt water.

The compounds of alkaloids is also used to differentiate the strains.

Pooideae
Agrostis canina, Alopecurus myosuroides , Bromus arvensis, Bromus hordeaceus, Bromus inermis , Bromus marginatus, Elymus tsukushiense, Festuca arundinacea, Elytrigia repens.

Arundinoideae
Stipa, Danthonia, Molinia caerulea.

Chloridoideae
Spartina, Distichlis

Panicoideae
Setaria

Speculations
In 1951 at Pont St. Esprit in France a poisoning case occurred due to bread.