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

Abstract

Rice is one of the most important edible crops in the world, along with wheat and corn. There are more than several tens of thousands of varieties or cultivars of rice in the world. Rice is markedly diversified from the viewpoint of genetics, morphology and properties. On the other hand, high quality rice is closely related by inbreeding to attain high palatability, high processing suitability, characteristic aroma, etc.Rice grains of the famous cultivars are traded or distributed at higher prices as "premium rice" than the ordinary rice because of their high palatability, processing suitability, special aroma, etc. As those premium rice grains sell at high price, some dishonest rice wholesalers or retailers blend low quality cheap rice with high quality premium rice and mislabel it as "high quality premium rice. Recently, rice consumers have tended to demand more information, such as cultivar name, location of production, year of production, etc., about rice which they purchase. For example, it is required under the JAS LAW (Law Concerning Standardization and Proper Labeling of Agricultural and Forestry Products in Japan) to display the name of rice cultivar on the package. Therefore, technology to identify rice cultivars is very important for breeders, farmers, inspectors, wholesalers, retailers, food industries and consumers.Rice cultivars have been identified on the basis of morphological characteristics of rice plants or grains, ripening ratio after crossing, isozyme patterns, etc. Cultivated rice (Oryza sativa L.) is one of the most polymorphic crop species in the world. In contrast, many cultivars of high quality rice or premium rice are closely related because inbred lines are often used for their development. Therefore, it is necessary to develop a time saving technology to differentiate rice cultivars clearly and precisely.DNA fingerprinting was developed in 1985 1) and is used for criminal investigation and trial at court. Recently, a novel cultivar identification method based on DNA polymorphism has been developed accompanied with the progress in molecular biology. DNA based markers have the obvious advantage of sampling the genome directly and RFLP analysis has been widely used for assessing variation of plants.2 4) RFLP analysis has been used to distinguish between species of Oryza 5) and particularly between indica and japonica types of Oryza sativa. 6)Recently, a PCR based marker system has been developed by Williams et al . 7) In this RAPD (Random Amplified Polymorphic DNA) method, short oligo nucleotides of arbitrary sequences are used to support the amplification of regions of the test plant genome and amplified DNAs are separated by gel electrophoresis.There are some reports on RAPD analysis of rice germplasm including indica and japonica types, to identify suitable parents for linkage map construction, and for gene tagging for drought resistance. 8,9) RAPD analysis was revealed to be reproducible and amenable for identification of each single plant line of F1 hybrid rice in China 10) and A...

Review of methods for the detection and quantification of adulteration of rice: Basmati as a case study

“…However, recently, protocols have been developed for identification of cultivars in the processed foods and bread containing both wheat and rice flours employing PCR based methods with improved DNA isolation protocol (Ohtsubo and Nakamura, 2007;Nakamura and Ohtsubo 2010). The protocol contains the preparation of the template DNA for PCR by the CTAB method followed by the extraction of DNA with 70 % ethyl alcohol (Nakamura and Ohtsubo 2010).…”

"Palatability Evaluation, DNA Analyses, and Functional Processing of Rice"

“…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 PCR method using template DNA prepared by the "enzyme treatment method" [43].…”