In this lab we infected resistant and susceptible tobacco plants (Nicotania tabacum) with the Tobacco mosaic virus. The plants labeled as n/n were susceptible and the plants labeled N/N were resistant. We will be able to tell if a plant becomes sick by looking for small necrotic lesions. The necrotic lesions are caused by plant cells recognizing the replicase protein in TMV and initiating apoptosis in those cells preventing the virus from replicating. We inoculated leaves of n/n and N/N plants with a series of dilutions made from a high concentration sample of TMV. We used a high concentration (50 ng/μl), a medium concentration (10 ng/μl), a low concentration (2 ng/μl), and finally some leaves were just rinsed with water as a control. We used carborundum powder on the leaves to make a wound for the TMV to infect cells.