TMV destroys chloroplasts in the leaf.

Explain how this could affect the growth of the plant.

Chloroplasts in the plants can accumulate high levels of toxic singlet oxygen, a reactive oxygen species formed during photosynthesis. Destroyed chloroplast makes the plant wither up and probably die because the plant's chloroplasts are the considered as the nutrient makers. The Chloroplast turns light into energy and without energy it will not be converted to sugar. Since they are the only thing in nature that is able to covert energy to sugar, it would greatly affect the process and affects growth of the plant which are food and oxygen producer so probably human would also run out of food and Oxygen.