Distribution of seed proteins in rice [Oryza sativa] grain of seed-protein mutant cultivars
2009
Ohdaira, Y.(National Agricultural Research Center for Western Region, Fukuyama, Hiroshima (Japan)) | Takeda, H. | Sasaki, R.
The distribution of seed storage proteins in rice grain of three seed-protein mutant cultivars with low ratios of digestible protein were compared with that of the normal-type cultivar 'Nihonmasari'. In seed-protein mutant cultivars and 'Nihonmasari', 44-45% of the total protein and 44-48% of the digestible protein were present in the 100-80% layers. The content of the digestible protein was highest in the 100-90% layer in seed-protein mutant cultivars, but it was highest in the 90-80% layer in 'Nihonmasari'. This tendency was more pronounced in low-glutelin 26-kDa-globulin-deficient cultivar than in low glutelin cultivars. In 'Nihonmasari', the contents of 37-39 kDa glutelin alpha and 22-23 kDa glutelin beta, which are major digestible proteins, were highest in the 90-80% layer. However, in seed-protein mutant cultivars, the contents of 57 kDa excess protein and 57 kDa protein, which occupy a high percentage of digestible protein, were highest in the 100-90% layer. Therefore, it was considered that the varietal difference in the digestible protein distribution was due to the differences in the distribution of each protein fraction. Up to 10% of digestible protein is distributed in the 80-70% layer and inner layers, which indicate that the effective milling percentage to decrease digestible protein content of rice grain is about 80%.
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