Differentiation and search for palatability-factors of world-wide rice grains by PCR method Sumiko NAKAMURA, Hiroshi OKADOME, Koh-ichi YOZA, Kazutomo HARAGUCHI, Tomoya OKUNISHI, Keitaro SUZUKI, Hikaru SATOH,* and Ken'ichi OHTSUBO National Food Research Institute, Kan-nondai, Tsukuba, Ibaraki 305-8642, Japan *Faculty of Agriculture, Graduate School, Kyushu University, Hakozaki, Higasi-ku, Fukuoka 812-8581, Japan It is well known that rice palatability is affected by variety or cultivar and variety characteristics are mainly determined by DNA structure. In this paper, palatability estimation method for rice grains was investigated using PCR primers accumulated for cultivar identification and novel primers developed by the relationship with starch properties or protein compositions. (1) It was shown that the proliferated DNAs by PCR, using the primers related with granule bound starch synthase (GBSS), soluble starch synthase (SSS), branching enzyme (BE), and debranching enzyme (DBE), revealed the marked differences between japonica and indica subspecies of rice, It seems to be plausible that the main component of rice grains is starch. (2) A part of DNA sequences of glutelin gene was shown to be different between japonica and indica subspecies as a results of PCR using glutelin-related and prolamin-related primers. (3) For the purpose of numerizing the results of PCR, discriminative DNA bands were binarized as 0 (disappeared) or 1 (appeared) and were subjected to the multiple regression analysis. Palatability estimation equations were developed using above mentioned independent variables based on the results of PCR against the dependent variables related with the palatability factors, such as amylose content, protein content, adhesiveness of cooked rice grains, and consistency of rice flours. These equations showed multiple regression coefficients of 0.92, 0.81, 0.93, and 0.84 for the calibration. Validation tests were carried out against the different rice samples and it revealed the adaptability of these estimation equations. Key words: rice; palatability; DNA analysis; PCR; multiple regression analysis (Received March 11, 2004)
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