What is the effector role of necrotrophic fungi like those causing apple scab?

Necrotrophic fungi, such as those responsible for causing apple scab, play a key role in the decomposition of plant tissues. These fungi typically invade the host plant and induce tissue death, allowing them to feed on the decaying organic matter. The primary strategy of necrotrophic pathogens is to kill host cells and then utilize the nutrients from the dead cells for their own growth.

This ability to facilitate decomposition is significant because it allows necrotrophic fungi to thrive in environments where they can effectively break down and exploit the organic material of the tissues they invade. By doing so, they not only impact the health of the host plant but also contribute to nutrient cycling in the ecosystem. The breakdown of plant materials by these fungi is an essential ecological process, which can lead to increased soil fertility and support the growth of subsequent plant life.

While necrotrophic fungi may indeed impact the host's ability to absorb nutrients or could inadvertently trigger plant defenses as a response to their attack, those actions do not encapsulate the primary effector role they play in the context of tissue necrosis and subsequent decomposition. Thus, the role of facilitating decomposition of tissues is the most accurate description of the effector role of necrotrophic fungi like those involved in apple scab.