Carbon assimilation by Claviceps purpurea growing as a parasite

Carbon assimilation by Claviceps purpurea, growing as a parasite on cereals, has been investigated by supplying the host plant with 14CO2 in a closed system. The presence of the pathogen induced the plant to exude photosynthate which contained high levels of sucrose. During the period of 14CO2 supply, 14C was incorporated into the sucrose and so the path of carbon into the parasite could be traced. Hexoses, derived by the action of the fungal sucrase on sucrose, were assimilated by the pathogen and largely converted into polyols - mainly mannitol and, to a lesser extent, trehalose. The rate of carbohydrate metabolism decreased with maturation of the ergot, and also showed qualitative differences between the basal and apical regions of the ergot which were probably a function of nutrient supply.