Shrunken, wrinkled, opaque white, brittle endosperm stains blue-black with I2-KI solution like nonwaxy type. In japonica background, endosperm is partly chalky, partly translucent, but is completely chalky in indica. Endosperm cells filled with round, compound starch granules and large number of small, round granules.
1. Sugary and two types of shrunken mutants. From left to right: normal (Kinmaze), sugary (chromosome 8) (EM5), shrunken-1-s (EM20), shrunken-1-a (EM6), and shrunken-2 (chromosome 8) (EM34) mutants.
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2. Scanning electron microscopic observation of endosperm tissues of various endosperm mutants. A: Normal (non-waxy variety‘Kinmaze’), B: Waxy mutant (chromosome 6), C and D: Dull mutants, E: Floury-1 mutant (chromosome 5), F: White core mutant, G: Sugary-1 mutant (chromosome 8), H: Shrunken-1 mutant (chromosome 1). (Photo courtesy H. Satoh)