Other researchers are modifying bananas to withstand these deadly foes, although this technique too is only in the first stages of testing. Tripathi and her colleagues are genetically engineering bananas that can withstand bacterial wilt and nematodes. Because all varieties of banana are vulnerable to bacterial wilt, conventional breeding can’t be used to develop resistant varieties. They have identified two genes in sweet peppers that are related to disease resistance. They boost the so-called hypersensitive response, which plants use to fight off disease. When the plant detects a pathogen, it kills its own cells that have come in contact with the germ. These patches of dead cells form a physical barrier that the pathogen can’t penetrate, preventing it from spreading further in the plant. The team has tested bananas that carry a pepper gene in carefully isolated fields in Uganda and found them completely resistant to bacterial wilt, Tripathi says. None of the plants even showed symptoms of illness. If these bananas had been regular, non-edited plants, each of them would have died.