Cultivar Identification of Rice (Oryza sativa L.) by PCR Method and its Application to Processed Rice Products

摘要

米（Oryza sativa L．）の品種は，食味，加工適性，価格等に影響するので，その判別技術の開発が必要とされている．筆者らは，米粒から鋳型DNAを抽出・精製する方法および適正なSTSプライマーを開発することにより，PCR法による米のDNA品種判別を可能にした．マルチプレックスプライマーセットは各国の広範な米の効率的な判別に有用であることを示し，2種類のコシヒカリ判別用セットを開発した．また，米飯等の米加工品からのPCR用鋳型DNAの抽出・精製用に，耐熱性α-アミラーゼによる80℃処理，次にSDS共存下でのプロティナーゼK処理とPCI精製処理を行う「酵素法」を開発した．これにより，米飯1粒や餅などを試料とする原料米のDNA品種判別が可能になった．%As the cultivars of rice affect markedly eating quality, processing suitability and price, identification or differentiation of rice cultivars is very important. The present authors developed suitable STS (sequence-tagged-site) primers for PCR (Polymerase Chain Reaction) and it became possible to identify rice cultivars using template DNA extracted and purified from rice grains. A multiplex primer set was shown to be useful to differentiate effectively rice cultivars produced in various countries by PCR. Two kinds of multiplex kit for identification of Koshihikari, the dominant cultivar in Japan, have been developed. The application of the cultivar identification method by PCR to processed rice products was investigated. The present authors developed an "enzyme treatment method," in which the gelatinized starch is decomposed by the heat-stable a-amylase at 80℃, followed by hydrolysis of proteins by proteinase K with SDS and purification of extracted DNAs by PCI (Phenol/Chloroform/ iso-amyl alcohol). It became possible to identify the material rice cultivars of the processed rice products, such as cooked rice and rice cake, by the PCR method using template DNA prepared by the "enzyme treatment method."