Time-resolved element mapping and characterization of storage proteins during soybean seeds development: a bottom-up strategy to increase protein content and quality

Abstract

Soybean (Glycine max (L.) Merrill) is one of the most important crops worldwide, responsible for a significative fraction of the Brazilian gross development product and standing out as a source of protein meal and vegetal oil for humans and animals. In this scenario, most of the proteins in soybean seeds are stowed for nitrogen supply during germination and early seedling development processes. These storage proteins are composed of two main fractions, the legumin (glycinin) and vicilin (²-conglycinin), which are deficient on sulfur-amino acids, including the methionine, an essential amino acid for humans and animals. Since this scarcity is related to the relative abundance of ²-peptide, a subunit of ²-conglycinin (vicilin), increasing the legumin content might increase methionine content on soybean storage proteins, increasing its quality and the nutritional status of soybean seeds. In this scenario, zinc, a vital micronutrient for plants, is reported to have strong binding sites on glycinin and acts as co-factor of methionine synthase. As the methionine biosynthesis takes place during the soybean seed filling, topping up time and tissue-specific Zn application might enhance it. However, little is known regarding the influences of Zn on soybean seed development and protein content. Herein, we hypothesize that understanding and controlling the dynamics of this mineral nutrient has the potential to enhance the nutritional quality of storage proteins on soybean seeds. (AU)