What does 'infection' refer to in plant pathology?

In plant pathology, 'infection' specifically refers to the invasion of a plant by a pathogen. This process involves the pathogen entering the plant's tissues, proliferating, and potentially causing disease. During infection, the pathogen can disrupt the plant's normal physiological functions, leading to various symptoms such as wilting, discoloration, or rotting of tissues.

Understanding this definition is crucial for recognizing how diseases develop in plants, as it highlights the initial and critical step in the disease cycle. While resistance to pathogen invasion and the plant's response to a pathogen are important concepts in plant pathology, they do not define the term 'infection.' Similarly, a superficial interaction between the plant and pathogen would not qualify as infection, which is characterized by a deeper and more invasive relationship. Thus, the focus on the pathogen's invasion makes the correct choice clear and underscores the importance of pathogen-host interactions in plant disease management.