Sexually transmitted infection in Silene latifolia

Microbotryum violaceum is a host-specific anther smut (fungus) disease that infects Silene latifolia and sterilizes the host plant. When infected with this disease, the flowers generate pathogenic spores, which can then be transferred to other plants by pollinating insects. Therefore, this disease is sometimes classified as a sexually transmitted infection.

They are fungal diseases that can infect different parts of the host plants (i.e. leaves, stems, flowers) and usually create black spores called teliospores in the infected area. Teliospores produce sporidia, white smut, and can survive under harsh environmental conditions. Therefore, the most effective way to prevent the spread of this fungal disease is to remove and destroy the infected area of the plant. Fungicides can be used to control the spread of smut; however, they must be applied before symptoms appear to be effective.

In male S. latifolia, M. violaceum eliminates pollen production in the anthers and replaces the pollen with fungal teliospores. These teliospores can then be transferred by pollinators to other plants, resulting in the spread of the infection. In females, the infection can subdue the development of the reproductive organs, styles and ovaries, resulting in complete sterilization.

Male S. latifolia tend to have a lower rate of infection compared to female S. latifolia because males have the ability to drop contaminated flowers before the entire plant is infected by M. violaceum; whereas, females do not have that male phenotype. So females hold onto the flowers with the intention to develop fruits carrying seeds with the purpose of creating offspring. However, these "offspring" merely carry the fungal disease and cannot develop into mature plants.

Sterilizing diseases do not attract a lot of attention in the research field compared to diseases that cause mortality in humans. However, there is an abundance of these diseases across biological kingdoms (i.e. plants, animals, fungi). They can create detrimental effects on a species’ population size because, although the organism does not immediately die, it cannot reproduce for the next generation. This chain of reaction leads to a decreased population size, which in extreme situations could lead to extinction. In addition, hosts with long life-spans can act as a “disease reservoir” in transmission by being a constant source for spreading the disease for years.

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