Microbotryaceae smut fungi

The Microbotryaceae family comprises a group of basidiomycete fungi that are obligate parasites of plants. The most well-known representative of this taxon is the pathogen causing anther smut in Caryophyllaceae, commonly known as Microbotryum violaceum. These pathogens specialize in infecting the reproductive organs of the host plant, replacing pollen with their own fungal spores.

The primary hosts affected by Microbotryaceae include wild and ornamental plants in the Caryophyllaceae family, such as campion and carnations. In an agronomic context, this pathogen is studied for its unique evolutionary specialization regarding transmission via insect pollinators, which serves as a model for understanding host-pathogen interactions.

Symptoms of the infection become visible when the anthers of the flowers are replaced by a dark purple or brownish powdery mass of teliospores instead of normal pollen. Externally, the infected plant may appear healthy until the flowering stage, after which the flower takes on a dusty appearance, and the plant often becomes sterile due to the fungal hormonal manipulation.

The spread of the infection occurs primarily through insect pollinators that carry fungal spores from infected flowers to healthy ones. Conditions of high humidity and moderate temperatures facilitate spore germination on the stigma, after which the mycelium penetrates plant tissues and systematically colonizes the host, eventually reaching the developing flower buds.

Protection measures include rigorous phytosanitary inspection of seeds and timely removal of infected plants in nurseries. Effective control strategies involve the eradication of diseased plants before spore dispersal occurs, as well as practicing crop rotation and maintaining spatial isolation for ornamental crops to mitigate the risk of insect-mediated transmission of the pathogen.