Stem rust fungus Flashcards
stem rust fungus
The invading rust fungus penetrates deep into the plant tissue. As the invasion progresses, the fungus produces spores that erupt from the plant’s surface, leading to the formation of pustules and new sites of infection. Soon, the plant’s stems and leaves are covered in fungal growth, which is carried by the wind. These fungal spores can travel great distances, eventually reaching other potential hosts.
To grow, the spores must find the necessary nutrients. They send out a germ tube in search of an entry point into the plant. A newly formed penetration tube breaks through the stem, allowing the fungus to extend further into the plant.
Once inside the stem, another structure called the haustorium enables the fungus to penetrate one of the plant’s cells. At this point, the fungus can extract nutrients from within the plant. It also begins to secrete small protein molecules known as effectors. This is a critical time for the plant; if it can detect the fungal effector proteins, it can attempt to stop the invasion.
The plant has specialized resistance proteins that act like an immune system. These resistance proteins can bind to the fungal effector proteins. This binding event alerts the plant that an infection is occurring. Now that the parasite is detected, the infected cells are sacrificed to cut off the energy supply to the invader. Ultimately, the fungus will starve, allowing the plant to continue its growth.
