Evaluation of the impacts of different nuclear DNA content in the hull, endosperm, and embryo of rice seeds on GM rice quantification

Abstract

Rice (Oryza sativa) is a main staple food in the world, and several genetically modified (GM) rice events have been approved for commercialization. To accurately quantify GM contents in rice derived products, we have evaluated the variation of seed DNA density and nuclear DNA content in the hull, endosperm, and embryo of rice seeds from 19 cultivars, as well as their impacts on GM rice quantification. Rice endosperm DNA accounts for 73.71% of total seed DNA, whereas the hull and embryo DNAs account for 3.98% and 22.31%, respectively. Two formulas were established to describe the relationship between GM content on the basis of weight ratio (GM(wt)%) and that on the basis of haploid genome copy number ratio (GM(hg)%) for the samples containing heterozygous GM rice seeds. These two equations were well confirmed in quantification of the heterozygous GM rice TT51-1 seeds containing the GM allele from a female parent or that from a male parent. This work is useful for accurate quantification of GM rice using reference materials containing the heterozygous GM rice seed powder.