Abstract
Genetic analysis of low-amylose content in a rice variety, ‘Milky Queen’, which is the N-methyl-N-nitrosourea (MNU)-induced mutant of the wild type variety, ‘Koshihikari’, was conducted. The F1 progenies derived from the reciprocal cross between Milky Queen and Koshihikari, showed an amylose content intermediate between that of the parents. However, the amylose content in the F1 (Koshihikari/Milky Queen) was higher than that in the F1 (Milky Queen/Koshihikari). Thus, gene dosage effect on the mutant gene was observed. Among the F2 seeds derived from Milky Queen/Koshihikari, high-amylose content (Koshihikari type) and low-amylose content (mutant type) seeds were segregated according to a 3: 1 ratio. Also, the segregation ratio in the BC1F1 (Milky Queen/Koshihikarii/Milky Queen) seeds fitted to the expected 1: 1 ratio. These results indicated that the mutation was controlled by a single recessive gene. An allelism test showed that the mutant gene in Milky Queen was not allelic to the known five du loci, but allelic to the wx locus.
