Rice is a staple food for nearly half of the world’s population.
In recent decades, genetic improvement in rice grain quality has
become important in rice breeding and considerable progress has
been made in breeding for quality. Several successful examples of
biofortification of rice to improve its nutritional quality and
combat nutritional deficiencies via a transgenic engineering
approach have been reported. Ye et al. introduced the β-carotene
synthesis pathway into rice endosperm by genetic engineering to
obtain golden rice that produces 0.16 mg/100 g of β-carotene in
the grains (1). Storozhenko et al. reported on the biofortification
of folate content in rice grains by overexpression of two genes
encoding GTP cyclohydrolase I and aminodeoxychorismate
synthase (2). Recently, the R0 and β subunits of soybean β-
conglycinin were expressed in rice seeds to improve the nutritional
and physiological properties of rice as a food (3). However, few
reports have described the biofortification of rice grains to
improve nutritional quality by conventional breeding (4). As
the first step toward achieving this goal, investigating diversity in
phytochemicals among rice varieties is necessary to find a way of
enriching these compositions through breeding.