Dang Dexuan^{1, 2,}, Hafeez Noor^{1, 2}, Lin Heying², Wang Lei^{1, 2}, Fida Noor¹

Sorghum which is one of the world's oldest cereal crops, originated in Africa and is an important food crop and a staple food for nearly 500 million people. Sorghum is a C4 crop with strong drought resistance, waterlogging resistance and salinity tolerance. It is widely grown in arid and semi-arid areas worldwide. Breeding sorghum varieties with high lysine content has always been an important breeding goal. However, conventional breeding has not led to a breakthrough because the gene controlling lysine content in grain is closely linked to seed shrinkage. The genes AK, DHPS and RNAi-LKR which control the accumulation and degradation of lysine in grain were transfered into sorghum. The content of lysine in sorghum grain was improved through metabolic engineering. The contents of lysine and the physicochemical properties of sorghum grains of different transgenic lines were determined, and the agronomic traits were evaluated, providing theoretical basis and germplasm resources for further screening of sorghum lines for high lysine contents. Sorghum grain has high content of resistant starch, low digestibility of protein, rich in fiber and some bioactive substances, so that sorghum has unique nutritional characteristics. Sorghum has been transformed from a traditional staple food into a functional food or as a food additive to improve food quality. The lipids in sorghum grains are mainly composed of unsaturated fatty acids, including oleic acid, linoleic acid, palmitic acid, linolenic acid and stearic acid. Sorghum also contains non- carbohydrate cell-wall polymers such as lignins with proportions constituting up to 20% of the total cell wall materials. Sorghum also has the potential to replace maize as animal feed.

amylose, food security, grain nutrition quality, sorghum, starch