Analysis of Low Amylose and Processability Fractured Endosperms Derived from Somatic Variation

Recently, improving eating quality and processing properties has become one of the most important objectives in japonica rice breeding programs in Korea. This study was carried out to determine the agronomy and physicochemical characteristics of the opaque endosperm rice “S-21-3-8” regenerated from seed-derived callus culture of a rice cultivar, “Ilpum”. S3 generation of opaque endosperm mutants selected from pedigree breeding was used for analysis of agronomic and physicochemical traits. Genetic segregation was observed at the highest frequency among opaque endosperm mutants, being present in 85.7% (12/14 lines) of the entire opaque lines. However, the major agricultural characteristics and grain traits of “S-21-3-8” were similar to those of a donor cultivar, “Ilpum”. “S-21-3-8” showed significantly lower (10.6%) amylose than those (17.7%) of “Ilpum” in brown rice, while the protein levels were similar to those of the donor plant. The grain hardness of “S-21-3-8” (1.67 kgf/mm) was lower than that of “Ilpum” (1.97 kgf/mm), resulting in a high flour-milling percentage. The loosely packed starch granules of “S-21-3-8” in the opaque endosperm were demonstrated by SEM analysis of cross-sectioned rice grains. The opaque endosperm mutants that were of somaclonal variations in the tissue culture will lead to improved eating quality and processing properties of rice.