Molecular regulatory mechanisms of protein and oil in soybean: a review

Soybean (Glycine max L.) is one of the most important crops for plant protein and edible oil sources worldwide. The seed protein and oil content of soybean are the core traits that determine its quality and economic value. There is a complex metabolic competition and coordinated regulation relationship between protein and oil accumulation. Elucidating the molecular regulatory mechanisms of their metabolism and interaction is of great significance for advancing high-quality soybean biological breeding. This article systematically reviews the research progress of newly identified genes and the underlying molecular mechanisms regulating protein and oil metabolism in soybean in recent years. Regarding protein accumulation, it focuses on the functional characteristics of the storage protein components controlling genes, the molecular mechanism of substrate allocation, key metabolic enzymes, and the molecular regulatory mechanisms mediated by transcription factors. In terms of oil regulation, it summarizes the composition and functional characteristics of fatty acids, discusses the key metabolic enzymes and functions related to the biosynthesis of fatty acids and triacylglycerols, and particularly summarizes the regulatory mechanisms of recently-discovered key transcription factors and the molecular modules for oil synthesis, which deepens the understanding of the molecular regulatory mechanisms of oil and protein accumulation in soybean. Finally, the article proposes several suggestions to advancing future research such as new gene discovery and mechanism analysis, construction of multi-gene coordinated regulation networks, technological innovation and efficient functional evaluation, as well as precise phenotypic evaluation.