Ergot alkaloids. VI. Nitrogen metabolism during the development of sclerotium of Claviceps purpurea.

The developmental transition of ergot from the sphacelial to the sclerotial phase is accompanied by marked changes in morphology, growth and metabolism. The production of alkaloids is paralleled by a concomitant protein synthesis, a decline in the contents of both total N and P, and an attendant rise in the value of the N/P ratio. The total level of free amino acids drops with proceeding development of the sclerotium. The most conspicuous drop, observed at the beginning of the production phase, is due to a sharp decrease in the level of free lysine. This drop attests to profound changes in the metabolism of the parasite in the period of transition from nonproducing sphacelium to producing sclerotium. The gradually decreasing level of free proline reflects the accumulation of the alkaloids. In a parasitic culture, proline is probably supplied in sufficient amounts by the host plant and the main difference between the metabolism of fungal sphacelium and sclerotium is a different utilisation of acetyl-CoA.