MODEL RELEASED. Genetically engineered tomato. Conceptual image of two scientists holding genetically modified tomatoes. Genetic engineering of plants involves altering their DNA (deoxyribonucleic acid) by adding genes from another organism. Traits such as resistance to diseases and pesticides can be introduced to the plant, which may save time and money during cultivation and harvesting. Tomatoes have so far been genetically engineered to be resistant to fungus, thereby prolonging their freshness during transportation. Many people actively campaign against genetic modification of food crops, fearing that it will harm the environment.