Lysine content and its relationship with protein content in indica rice landraces of China

Lysine is a limiting essential amino acid in rice. This study determined the variation in lysine content and evaluated the relationship between lysine and protein content in indica rice landraces of four provinces (Guangdong, Guangxi, Hunan, and Sichuan) in China by using the data (n = 654) collected from the Chinese Crop Germplasm Information System. Results showed that grain lysine content ranged from 0.25 % to 0.54 %, with 139 landraces having a grain lysine content of more than 0.40 %. Lysine content of protein ranged from 28.4 to 48.1 mg g-1, with 20 landraces having a lysine content of protein of more than 45.0 mg g-1. Guangdong had 5-21 % higher median of grain lysine content and 3-6 % higher median of lysine content of protein than the other three provinces. Lysine content of protein was significantly negatively related to protein content across four provinces.