New Mutants of Specialty Rice Induced from Ilpumbyeo, a High-Quality Rice Cultivar, by MNU(N-Methyl-N-Nitrosourea) Treatment on Fertilized Egg Cells

Abstract

Various mutants of specialty rice were derived from Ilpumbyeo, a high-quality japonica rice cultivar, through muta-tion breeding by MNU treatment on fertilized egg cells of rice spikelets. The selected mutants revealed glutinous, semi-glutinousfthem were glutinous or dull and chalky endosperm. The amylose content of semi-glutinous dull mutants ranged from 6.0 to13.0%. The specialty rice varieties induced from Ilpumbyeo by the chemical mutagen were a high-yielding glutinous rice‘Suweon 428’, a semiglutinous rice ‘Baegjinju’, an opaque non-glutinous rice ‘Seolgaeng’, a high-amylose and fiber-rich rice‘Goami 2’, and a giant-embryo rice ‘Keunnun’. They showed accompanying mutation effects of about one-week earliness ongrain yield in ‘Goami 2’ and Keunnun as compared with Ilpumbyeo, the original cultivar. The alkali digestion value (ADV) ofBaegjinju resembled to the glutinous mutant Suweon 428 showing slightly lower ADV than that of Ilpumbyeo. The ADV ofGoami 2 was of similar level to that of Ilpumbyeo, but it revealed quite different pattern of ‘swelling’ in stead of ‘spreading’ pat-tern of the original cultivar. The amylose content was markedly lower in Baegjinju by about 50%, but was much higher in Goamistructural characteristics of endosperm cell or compound starch granules from that of the original variety. Most of the endospermcells of Seolgaeng were also packed with round-shape compound starch granules. The opaque endosperm of Seolgaeng may beuseful for fermented food processing such as saccharized beverage or rice wine because of a lot of air space in endosperm. Thegiant-embryo rice, Keunnun produced about 2~3 times higher content of γ-aminobutyric acid by soaking in water as comparedwith the original variety.