Grain lysine enrichment and improved stress tolerance in rice through protein engineering.

This article focuses on engineering the rice enzyme dihydrodipicolinate synthase (DHDPS) to overcome lysine feedback inhibition, thereby increasing lysine content in rice grains and enhancing abiotic stress tolerance. By introducing specific mutations (S157N, E162K, A166T) into the rice DHDPS gene (LOC_Os04g18200), researchers created a lysine feedback-insensitive enzyme (mOsDHDPS) that, when expressed under an endosperm-specific promoter in rice cultivar IR64, led to a 29% increase in grain lysine and 15% higher total protein without compromising yield or grain quality. The transgenic rice also exhibited improved tolerance to drought and salinity stress, maintaining higher photosynthetic efficiency, antioxidant enzyme activities, and redox homeostasis, with lysine levels preserved even after cooking under stress conditions. This study demonstrates a protein engineering approach that enhances both nutritional quality and stress resilience in rice, offering potential benefits for food security and nutrition in regions dependent on rice as a staple.