Soybean vegetative storage proteins (S-VSPs) are lysine-rich leaf proteins, originally found to accumulate to high levels in depodded soybean plants. In the present study, we overexpressed S-VSPβ, the ruminant stable subunit of the S-VSP genes, in transgenic tobacco plants. The S-VSPβ protein accumulated in all organs studied, but its level declined drastically with leaf age. This instability of S-VSPβ could be overcome either by elevating free lysine levels or by coexpressing S-VSPβ with S-VSPα. High levels of rumen-stable, lysine-rich proteins is expected to improve absorption of lysine by ruminants. Furthermore, the expression of S-VSPs in heterologous plants led to a significant increase in total soluble lysine, suggesting that these proteins may also permit better assimilation of lysine by humans and monogastric animals.
Bibliographical noteFunding Information:
This project was supported by the Chief Scientist of the Ministry of Agriculture, grant No. 259-0088.
- Improved nutritional quality
- Protein-bound lysine
- Soybean vegetative storage proteins
- Transgenic tobacco plants