Question

Wheat stem rust (Puccinia graminis) is a fungus that can cause disease in wheat plants. The fungus infects a wheat plant by injecting proteins into the plant's cells. These proteins help the fungus grow and reproduce, harming the plant in the process.

To prevent losing crops to this disease, farmers around the world grow wheat plants that are resistant to wheat stem rust. Resistant plants make their own proteins that detect the injected proteins of wheat stem rust and then trigger a physiological response. This response prevents the fungus from growing on the plants and causing disease.
In 1999, a new strain of wheat stem rust was discovered in Uganda. This strain, called Ug99, can cause disease on wheat plants that were previously resistant to stem rust. According to the Food and Agriculture Organization of the United Nations, Ug99 is a major threat to global wheat production.
Based on the information above, which of the following is most likely true about the ancestry of wheat stem rust strain Ug99?

Answer 1

The ancestry of the wheat stem rust strain Ug99 is most likely related to the genetic changes in the fungus over time.

Step-by-step explanation:

The ancestry of the wheat stem rust strain Ug99 is most likely related to the genetic changes in the fungus over time. The fungus is able to evolve and become unrecognizable to the resistant plants by not producing a specific protein that the avirulent fungi produced. This virulence is typically recessive in the pathogen, meaning that it is unable to produce something that the wild type does make. The resistant plants, on the other hand, have a dominant gene that allows them to recognize and respond to the presence of the injected proteins by initiating a physiological response.

Answer 2

The ancestry of the wheat stem rust strain Ug99 can be traced back to the genetics of both the fungus and the wheat plant. The plant's resistance involves the ability to detect and respond to the fungus. However, Ug99 has evolved to overcome the plant's defenses.

Step-by-step explanation:

The ancestry of the wheat stem rust strain Ug99 can be traced back to the genetics of both the fungus and the wheat plant. Resistance to the disease involves the ability of the plant to recognize invasion by the fungus and respond to it. The plant produces its own proteins that detect the injected proteins of wheat stem rust and trigger a physiological response to prevent the fungus from growing and causing disease. However, the Ug99 strain of wheat stem rust is able to cause disease on previously resistant wheat plants, indicating that it has evolved to evade the plant's defenses.