Fig. 1

Lifecycle of Microbotryum lychnidis-dioicae. The infection cycle for M. lychnidis-dioicae) is shown. Infection begins when diploid teliospores germinate on a suitable plant surface, and after meiosis, produce linear tetrads of haploid basidiospores. These cells may mate with cells of opposite mating-type (i.e., a1 or a2), either directly within the tetrad or after budding to yield free yeast-like sporidia. Mated cells form conjugation bridges and, upon receiving suitable cues from the host plant, develop into dikaryotic hyphae that penetrate the host tissue. The hyphae progress systemically through the plant and migrate to the flower primordia. There nuclear fusion (karyogamy) occurs, as the hyphae break up and develop into diploid teliospores that replace the pollen in the anthers of the developing flowers. Pollinator species are then able to transmit the spores to other uninfected flowers, thus completing the cycle