Agronomic,molecular and antioxidative characterization of red- and purple-pericarp rice (Oryza sativa L.) mutants in Taiwan

Pigmentation of rice grain is controlled by Ra, Rc and Rd genes, and the expressions of these genes differ among red-, purple- and white-pericarp varieties. The present study examined the grain yield and the expression of Ra, Rc and Rd genes in non-waxy white-pericarp rice SA418 and waxy white-pericarp rice SA419 and their respective red-pericarp and purple-pericarp mutants with waxy or non-waxy endosperm. Significant variations in 100-grains weight and grain yield were observed among the tested mutants. The Ra was expressed in purple-pericarp mutants, while the Rc was expressed in red-pericarp mutants. The total phenolics, total flavonoids, total anthocyanins and total proanthocyanidins contents and antioxidant activities in the bran part also differed among the mutants. Non-waxy red-pericarp mutant M-69 had heavier 100-grains weight (2.86 g), contained more total phenolics (49.37 mg g⁻¹ bran dry weight) and produced higher grain yield (6.93 t ha⁻¹) than white-pericarp rices SA418 (2.43 g, 2.89 mg g⁻¹ bran dry weight and 2.80 t ha⁻¹, respectively) and SA419 (2.62 g, 2.20 mg g⁻¹ bran dry weight and 6.73 t ha⁻¹, respectively). Thus, the polished rice grain of M-69 can be used for staple food consumption, and its bran parts are useful for producing health-promoting by-product.