A rice mutant with a giant embryo has increased levels of lipophilic antioxidants, E vitamers, and γ‐oryzanol fraction

Abstract

Background and objective Lipophilic compounds in rice bran have health beneficial and functional properties. These lipophilic antioxidants in a giant embryo mutant (GEDrew) derived from a tropical japonica variety Drew were determined to evaluate its potential as a specialty variety. Findings GEDrew had double the size of embryo and lower kernel weight than Drew. The majority of the tocols in the embryo were in the form of tocopherols with α‐tocopherol accounting for approximately 70%, while the tocopherols in bran ranged from 22% to 43% of total tocols. On a per embryo basis, GEDrew had a higher quantity of tocols compared with Drew; however, on a weight basis, the concentration of tocols in GEDrew was less than Drew. The γ‐oryzanol concentration in embryos was the same for both the mutant and wild type. The smaller brown rice kernel size and bigger embryo size of GEDrew resulted in higher proportion of bran + embryo (w/w), which led to higher total tocopherols, tocotrienols, and γ‐oryzanol in the whole grain of GEDrew relative to Drew. Conclusion A rice mutant with a large embryo had an elevated level of γ‐oryzanol and tocols, both as a group and as individual homologs, in whole grains as compared to the wild type. Significance and novelty GEDrew has the potential to be grown as a specialty rice variety for the purposes of isolating its bran, oil, and lipophilic antioxidants for use by the food and cosmetic industries.

Effects of Germination, Fermentation and Extrusion on the Nutritional, Cooking and Sensory Properties of Brown Rice Products: A Comparative Study

“…The physical force of the extruder damaged the cell membrane where the γ-oryzanol was present, and γ-oryzanol in damaged particles may be more easily oxidized [ 25 ]. γ-oryzanol has previously been shown to display various biological activities, including antioxidant, anti-inflammatory and anti-tumor activities [ 36 ]. In addition, γ-oryzanol has also been reported to reduce blood cholesterol levels in humans and hamsters [ 16 ].…”

Identification of a New Giant Emrbryo Allele, and Integrated Transcriptomics and Metabolomics Analysis of Giant Embryo Development in Rice

“…It is therefore important to studying its molecular basis for breeding high-nutrition rice varieties. However, many previous studies focus on genetic basis of giant embryo rice or nutritional measurements performed on mature rice grains, which lead to little is known about the causal relationship between metabolites and related genes during rice embryo development ( Koh et al, 1996 ; Qian et al, 1996 ; Dong et al, 2003 ; Zhang G. H. et al, 2005 ; Zhang L. L. et al, 2005 ; Park et al, 2009 ; Seo et al, 2011 ; Jeng et al, 2012 ; Wang et al, 2013 ; Chen et al, 2020 ).…”

“…It is therefore important to studying its molecular basis for breeding high-nutrition rice varieties. However, many previous studies focus on genetic basis of giant embryo rice or nutritional measurements performed on mature rice grains, which lead to little is known about the causal relationship between metabolites and related genes during rice embryo development (Koh et al, 1996;Qian et al, 1996;Dong et al, 2003;Zhang G. H. et al, 2005;Park et al, 2009;Seo et al, 2011;Jeng et al, 2012;Wang et al, 2013;Chen et al, 2020). Nagasawa et al (2013) showed that the embryo cell volume in GE mutant was more than twice that of the wild-type, but the difference of cell number was not obvious, so the abundance of nutrients in giant embryo rice may be due to the increase of embryo cell volume (the larger the container, the more it could hold).…”

“…Moreover, compared with conventional rice, giant embryo rice exhibits greatly increased contents of amino acids, vitamin E, gamma-oryzanol, phenols, and minerals, especially gamma amino-butyric acid (GABA) ( Zhang L.L. et al, 2005 ; Park et al, 2009 ; Seo et al, 2011 ; Jeng et al, 2012 ; Wang et al, 2013 ; Chen et al, 2020 ). GABA is a free amino acid that functions as an inhibitory neurotransmitter and typically accumulates in rice embryos.…”

“…Giant embryo rice, which refers to rice cultivars with larger embryos, whose volume is typically more than twice that of conventional rice, is an ideal material for studying rice embryo development. Moreover, compared with conventional rice, giant embryo rice exhibits greatly increased contents of amino acids, vitamin E, gamma-oryzanol, phenols, and minerals, especially gamma amino-butyric acid (GABA) Park et al, 2009;Seo et al, 2011;Jeng et al, 2012;Wang et al, 2013;Chen et al, 2020). GABA is a free amino acid that functions as an inhibitory neurotransmitter and typically accumulates in rice embryos.…”