ENHANCING AMINO ACID QUALITY IN CEREALS: GENETIC AND BREEDING PERSPECTIVES

Abstract

Cereal grains are central to global food security, yet their nutritional quality is frequently constrained by inadequate levels of essential amino acids, particularly lysine, methionine and tryptophan. Improving amino acid composition is an important component of developing nutritionally enhanced and climate-resilient cereal crops. This review critically examines the genetic, biochemical and breeding factors governing amino acid profiles in major cereals, with emphasis on rice, wheat, maize and barley. The major metabolic pathways underlying essential amino acid biosynthesis, together with genes involved in synthesis, transport and storage are discussed in relation to grain nutritional quality. Advances in chromatographic, spectroscopic and bioanalytical approaches have improved the accuracy and throughput of amino acid profiling, while genomics, transcriptomics, proteomics and metabolomics have accelerated the discovery of regulatory genes, genomic regions and metabolic networks. Conventional breeding, induced mutagenesis, marker-assisted selection, quantitative trait locus mapping, genomic approaches and precise genome editing have expanded opportunities for improving limiting amino acids, with quality protein maize providing an established example of successful nutritional enhancement. However, trade-offs among amino acid composition, grain yield, protein content, environmental stability and genotype-by-environment interactions remain major challenges. Future breeding strategies should integrate diverse germplasm, multi-omics information, high-throughput phenotyping and predictive approaches to develop stable, high-yielding cereals with superior protein quality and nutritional value.