What is one of the major symptoms of a Tobacco/Tomato mosaic tobamovirus infection?

The choice of shoestring symptoms as a major symptom of a Tobacco/Tomato mosaic tobamovirus infection is correct because this specific symptom is associated with the viral infection in the leaves of affected plants. Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV), both members of the tobamovirus group, commonly induce stunted growth and a characteristic leaf distortion known as shoestringing. This symptom manifests as elongated, distorted leaves that resemble a shoestring, which is indicative of the virus's effects on plant development.

Other symptoms linked to TMV and ToMV include mottling, chlorosis, and blistering of leaves, but shoestring symptoms are particularly noted for their distinct appearance in infected plants. The virus disrupts normal cellular processes in the plant, leading to these striking morphological changes. Thus, shoestring symptoms serve as a clear and identifiable indication of infection by the Tobacco/Tomato mosaic tobamovirus.