The transgenic maize line TC6275 was genetically engineered to resist European Corn Borer (ECB), Southwestern corn borer (SWCB), fall armyworm (FAW), and black cutworm (BCW), and to a limited extent, corn earworm (CEW), by producing its own insecticide. TC6275 was also developed to express tolerance to the herbicide glufosinate ammonium. Two novel genes, a truncated cry1F gene and the bar gene were introduced into the maize hybrid line Hi-II using Agrobacterium-mediated transformation.

The cry1F gene, isolated from the common soil bacterium Bacillus thuringiensis var. aizawai, produces the insect control protein Cry1F, a delta-endotoxin. Cry proteins, of which Cry1F is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1F is lethal only when eaten by the larvae of lepidopteran insects (moths and butterflies), and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for the delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.

TC6275 maize also was developed to allow for the use of glufosinate ammonium as a weed control option, and as a breeding tool for selecting plants containing the cry1F gene. The herbicidal mode of action of glufosinate ammonium is related to the activity of glutamine synthetase (GS), the enzyme required for the synthesis of the amino acid glutamine. L-phosphinothricin, the active ingredient of glufosinate ammonium, is a structural analog of glutamate, and acts as a competitive inhibitor. After application of the herbicide, L-phosphinothricin competes with glutamine for its active sites on GS. The results of the inhibition of GS are an accumulation of ammonia in the plant, a reduction in the synthesis of glutamine, and an inhibition of photosynthesis. This causes the death of plant cells, and eventually, the entire plant. TC6275 maize contains the bar gene, which codes for the production of the enzyme phosphinothricin acetyl-transferase (PAT). This enzyme acetylates L-phosphinothricin rendering it inactive in the plant. The PAT enzyme is not known to have any toxic properties. The bar gene was isolated from the soil bacterium Streptomyces hygroscopius, the same organism from which L-phosphinothricin was originally isolated.