Tobacco mosaic virus (TMV) has a wide host range but is of special concern on solanaceous plants. Symptoms include yellow and green mottling, upward curling, necrotic leaf spots, leaf distortion, and overall stunting. Symptoms on plants in this photo are very subtle and could be mistaken for nutrient deficiency such as iron.
TMV is not transmitted by insects, but is transmitted mechanically in sap, by contact with contaminated equipment, by vegetative propagation, and it can be carried in seed. Once a plant is infected with a virus, it cannot be cured.