Functional analysis for 'opaque endosperm' of somaclonal mutant in rice (Oryza sativa L.)

This study was carried out to investigate the genetic variations observed in tissue culture progenies of the rice cultivar 'Ilpum'. The results indicated that 21.5% (64 lines) of the progenies showed significant differences from the donor cultivar 'Ilpum'. Among the progenies, 1.7 % had opaque endosperm. One new copy of a retrotransposon, Tos17, was detected in the endosperm mutant, the copy number and activation of other two retrotransposons, Tos12 and Tos15, did not appear in 'Ilpum'. Flanking sequence tag (FST) analysis of Tos17 in the opaque endosperm indicated that new copy of Tos17 was transposed onto chromosome 1. The annotated gene was highly correlated with histone H2B regulating vitamin E and carbohydrate metabolism. The metabolic consequences of histone H2B affected the starch accumulation in the opaque endosperm mutant. The opaque endosperm was clearly distinguishable due to its chalky characteristics. Amylose and fat contents of the opaque endosperm were slightly lower than those of the 'Ilpum'. The opaque endosperm that were of somaclonal variations suggested that they can be used for insertional mutagenesis and functional analysis of genes. Also the opaque endosperm that was of somaclonal variations in the tissue culture will remarkably breed a safer method as compared to the GM plants of T-DNA insertions.