Genetic Analysis of Low-amylose Content in a Rice Variety, ‘Milky Queen’

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 proge- nies 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 con- tent (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.