Puccinia monoica

Taxobox
name = "Puccinia monoica"
regnum = Fungi
phylum = Basidiomycota
classis = Urediniomycetes
subclassis = Incertae sedis
ordo = Uredinales
familia = Pucciniaceae
genus = Puccinia
species = "Puccinia monoica"

Puccinia monoica is a rust fungus of the genus "Puccinia" that inhibits flowering in its host plants (those of the "Arabis" genus) and transforms host behavior in order to facilitate sexual reproduction to pass on its genes. Infection occurs when the fungus sends its throughout the stem of the mustard plant, siphoning off some of the nutrients of its host. However, to reproduce, "Puccinia monica" must exchange genes with the "Puccinia" inside another mustard plant. The fungus sterilizes the plant, preventing it from sending up its own flowers. Instead, the fungus forces the infected plant to turn clusters of its leaves into brilliant "flowers" (pseudoflowers).

These mimetic flowers are identical to others found on the mountains of Colorado, where the mustard plant is found, not only in visible light but also in ultraviolet. Since bees "see" in the ultraviolet range, these flowers are more attractive to the pollinating insects. In addition, the fungus produces a distinct scent to attract insects; this olfactory appeal has allowed the fungus to evolve and "improve" upon the mimicry system by facilitating proper transfer of fungal spermatia and pollen. [Roy, B.A. and Raguso, R.A. Olfactory versus visual cues in a floral mimicry system. Oecologia, V. 109, No. 3: 414-426] The bees feed on a sweet, sticky substance that the fungus forces the plant to produce on the imitation flowers. The fungus forces its sperm and its female sex organs into them, so that the bees can fertilize the fungus as they travel from plant to plant. [Zimmer, C. Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures.]

References