MICROCYCLIC CONIDIATION CYCLES IN EPICHLOE-TYPHINA

Germination of ascospores in Epichloe typhina was described earlier as iterative germination in which each part spore of an ascospore germinated and produced conidia without an intervening mycelial phase. In the present study it was determined that the conidia produced by iterative germination also undergo an additional series of microcyclic conidiations. Thus, conidia produced from the ascosporic microcyclic structure germinated and produced other conidia, which also germinated producing yet another microcyclic structure. It was only after the third stage of microcyclic conidiations that mycelial development occurred. Microcycle conidiation in E. typhina is viewed as an obligate developmental sequence since no alternative process was observed. This distinguishes it from microcycle conidiation reported in other fungi where microcycle conidiation is facultative, being inducible only under certain laboratory conditions. Although unexplored, microcyclic conidiation may be a fundamentally important aspect of the life history of E. typhina and a variety of other fungi.