A New Mutant Gene Lowering Amylose Content in Endosperm Starch of Rice, Oryza sativa L.

Abstract

The present study was undertaken to investigate the starch properties and inheritance of a newly induced mutant of rice. The endosperm of the mutant is dull and can be readily distinguished from the waxy as well as nonwaxy endosperms. The amylose content of the dull mutant was half as low as that of the nonwaxy counterpart. No conspicuous differences regarding the distribution of unit chain length of amylopectin existed between dull mutant and the normal counterpart. The starch properties of the dull mutant were determined three weeks after heading. Judging from the genetical analysis for amylose content of the dull mutant, it was considered that amylose production in the dull mutant is controlled by a single recessive gene which is nonallelic to the wx alleles. The amylose content did not decreased proportionally with the number of du alleles, in contrast to the proportional reduction in amylose content with the number of wx alleles. The existence of a low amylose mutant gene makes it possible to improve the eating quality of rice grains.