aeciospores

Aeciospores are a type of fungal spore produced by rust fungi during the aecial stage of their life cycle. They are formed in aecia on the alternate (aecial) host of heteroecious rust species and function to initiate infection of the primary host, completing part of the rust life cycle.

Most rust fungi that require two hosts alternate between a primary host and an alternate host. Basidiospores from the telial stage infect the alternate host, leading to the development of aecia that produce aeciospores; these spores then disperse to infect tissues on the primary host, where they may give rise to uredinia and further stages before the cycle continues.

In terms of morphology, aecia produce aeciospores; the spores are typically thick-walled and variably shaped and sized. Many species produce two-celled aeciospores, though there is considerable variation among rust species. Aecia are often cup- or pustule-like structures containing chains or clusters of spores.

Ecology and importance: Aeciospores are wind-dispersed and play a key role in moving infection between hosts. They are involved in some agriculturally important rust diseases. A well-known example is cedar-apple rust, where aecia form on junipers and release aeciospores that infect apple trees. Not all rusts produce an aecial stage; autoecious rusts complete their life cycle on a single host.