Ruminants and humans are unable to synthesize essential amino acids (EAAs) and conditionally essential amino acids (CEAAs) under normal conditions and need to acquire them from plant sources. Maize plays, as a major crop, a central role in global food security. However, maize is deficient in several EAAs and CEAAs. Genetic engineering has been successfully used to enrich the EAA content of maize to some extent, including the content of Lys, Trp, and Met. However, research on other EAAs is lacking. Genetic engineering provides several viable approaches for increasing the EAA content in maize, including transformation of a single gene, transformation of multiple genes in a single cassette, overexpression of putative amino acid transporters, engineering the amino acid biosynthesis pathway including silencing of feedback inhibition enzymes, and overexpression of major enzymes in this pathway. These challenging processes require a deep understanding of the biosynthetic and metabolic pathways of individual amino acids, and the interaction of individual amino acids with other metabolic pathways.

反刍动物和人类在正常条件下无法合成必需氨基酸（EAAs）和条件必需氨基酸（CEAAs），需要从植物来源获取。玉米作为一种主要作物，在全球粮食安全中发挥着核心作用。然而，玉米缺乏几种 EAA 和 CEAA。基因工程已成功地在一定程度上丰富了玉米的EAA含量，包括Lys、Trp和Met的含量。然而，缺乏对其他 EAA 的研究。基因工程提供了几种增加玉米中 EAA 含量的可行方法，包括单个基因的转化、单个基因盒中多个基因的转化、假定氨基酸转运蛋白的过表达、改造氨基酸生物合成途径，包括反馈抑制酶的沉默，以及该途径中主要酶的过表达。这些具有挑战性的过程需要深入了解单个氨基酸的生物合成和代谢途径，以及单个氨基酸与其他代谢途径的相互作用。