What is commonly seen in plants that have been infected with a virus?

Plants that have been infected with a virus often exhibit mottled leaves and unusual fruit shapes as hallmarks of viral infection. This mottling generally presents as areas of discoloration, often lighter or darker than the surrounding tissue, which indicates that the plant's normal physiological function has been disrupted due to the virus interfering with the plant's cellular processes. These visual symptoms occur because the virus alters the way the plant cells develop and respond to environmental stimuli, leading to deformities in both foliage and fruit.

Unusual fruit shapes can arise because the virus can affect the way cells divide and differentiate, potentially leading to malformed or less productive fruit. This disruption of normal growth patterns is a direct consequence of the plant's reaction to viral pathogens, which is why these symptoms are considered typical indicators of viral infection in plants.

Other symptoms attributed to plant health, like bright flowers or robust growth, are typically associated with a healthy plant and do not occur in the presence of viral infections. Similarly, rapid growth and lush foliage or general vigor and health would contradict the negative impact of a viral infection on a plant's overall health and development.