Genetic regulations of the oil and protein contents in soybean seeds and strategies for improvement

Soybean [Glycine max (L.) Merr.] is an important legume crop that provides high-quality vegetable protein and oil. In general, oil makes up around 19% of the dry weight of a soybean seed, with the five most abundant fatty acids being palmitic, stearic, oleic, linoleic, and linolenic acids. Storage proteins make up roughly 40% of the dry seed weight, mainly consisting of β-conglycinin (7S globulin) and glycinin (11S globulin). The content and composition of soybean seeds are valuable traits controlled by a complex genetic background and various growth conditions. Environmental stresses, including drought, temperature, and salinity, could severely reduce seed productivity and alter the chemical compositions. Understanding the genetic regulations of oil and protein biosynthesis and how they are affected by abiotic stresses is imperative to enhancing the seed quality. This chapter reviews how oil and protein contents and compositions are affected by environmental conditions, summarizes the genes involved in protein and oil biosynthesis/metabolism, emphasizes the genetic mechanisms of oil/protein accumulation, and offers strategies for improving soybean production both quantitatively and qualitatively.