Screening and Breeding for Biofortification of Rice with Protein and High Lysine Contents

A total of 134 domestic and foreign genetic resources were analyzed for their protein and amino acids contents in order to identify breeding lines with high lysine content to improve nutritional components of rice. The protein contents ranged between 6.7% and 14.8%, with an average of 8.7%. The Dharial mutant-derived lines had relatively high protein content with the highest amino acids content of 130.16 mg/g and the highest lysine content of 3.86 mg/g which is about 5 times higher than that of the parent. In the case of mutant-derived lines with high floury endosperm such as Goami2, Dodamssal, Milyang320 and LA1, the total amino acids content was as low as 72.61-82.0 mg/g; however, lysine content ranged high between 2.64-3.35 mg/g with lysine ratio to the total amino acids was 3.6%-4.1% which is higher than the average lysine content ratio of 3.0%. Furthermore, correlation analysis revealed a very strong positive correlation between the total amino acids and total protein contents. In contrast, lysine content showed no significant correlation neither with total amino acids nor with protein contents. The lysine content of Milyang320, which was grown in 5 regions across Korea was 0.33%, showing an increase of about 22% compared to that recorded in Nampyeong (0.27%). Therefore, these data suggest that lysine content of Milyang320 is controlled genetically and could be serve as a source in high lysine rice breeding program.