MUTANTS HAVING A LOW CONTENT OF 16-KDA ALLERGENIC PROTEIN IN RICE (ORYZA-SATIVA L)

Rice mutants containing low levels of the 16-kDa allergenic protein, w hich is the main allergen in the rice grain for patients of atopic der matitis due to the intake of rice, were screened, and 4 independent mu tant lines with small amounts of this protein were found by SDS gel el ectrophoresis and immunoblot analysis. These mutants were grouped into two types. Two mutant lines, 85KG-4 and 86RG-18, contained low levels of the 16-kDa and 26-kDa polypeptides and a high level of the 57-kDa polypeptide. The 16-kDa polypeptide content of these mutants was about half that of the original cultivars. Homozygous lines were developed, and these showed normal growth and seed set. The other 2 mutant lines , 87KG-970 and 89WPKE-149, showed traces of the 16-kDa and 26 kDa poly peptides and contained a high level of the 13 kDa polypeptide. The hom ozygous plants of this type were sterile. All of the mutant lines had floury endosperms. Genetic analysis suggested that low 16-kDa polypept ide content is controlled by a single recessive gene. Attempts to sepa rate of the genes for low 16-kDa polypeptide content and floury endosp erm by crossing with the original cultivar were unsuccessful, suggesti ng the tight linkage of these two genes or pleiotropism of a single mu tated gene. The relationship between low 16-kDa polypeptide content an d the floury character and the possible use of the mutant as a low all ergen rice are discussed.