Which fungi can survive and invade host tissues, causing disease?

Pathogenic fungi are specifically adapted to invade host tissues and cause diseases in plants, animals, or humans. These fungi possess various mechanisms, such as enzymes and toxins, that allow them to penetrate host cells, evade the immune responses of the host, and extract nutrients from the living tissues. This can lead to a wide range of symptoms, including wilting, discoloration, or even plant death, depending on the nature of the pathogen and the host organism.

Mycorrhizae are beneficial fungi that form symbiotic relationships with plant roots, enhancing nutrient absorption and aiding in water uptake, which is fundamentally different from the behavior of pathogenic fungi. Similarly, symbiotic fungi also engage in mutualistic relationships with their hosts rather than causing harm. Saprophytic fungi play a role in breaking down dead organic matter, which is essential for ecosystem nutrient cycling, but they do not invade living tissues or cause diseases. This differentiation highlights the specific role that pathogenic fungi play in the context of plant and animal health, underlining why the identification of pathogenic fungi is critical in horticulture and agriculture.