Low Glutelin Content Research Articles

High-resistant starch and low-glutelin content 1 rice benefits gut function in obese patients

The intestinal microbiota plays a crucial role in human health, yet the impact of high-resistant starch and low-glutelin rice in the gut of obese individuals remains unexplored. In this study, different types of rice, namely japonica rice (control), low-glutelin content 1 rice (Lgc1), high-resistant starch and low-glutelin content 1 rice (HR + Lgc1), and commercially available low-glycemic index rice (LowGI), were utilized as samples to examine their in vitro digestion and fermentation, as well as the impact of HR + Lgc1 on the intestinal microbiota in obese individuals. The findings revealed that HR + Lgc1 rice exhibited lower in vitro digestion rates for starch and protein compared to the other three types. Following 24 h of in vitro fermentation, the total short-chain fatty acid content in HR + Lgc1 was 108.67 mmol/L, which was 60.33, 51.26, and 17.29% that in control, Lgc1, and LowGI, respectively. Moreover, HR + Lgc1 rice displayed an inhibitory effect on the production of harmful branched-chain fatty acid metabolites. Analysis through 16S rDNA sequencing indicated that, after fermentation, HR + Lgc1 significantly enhanced the abundance of beneficial bacteria such as Bifidobacterium, Parabacteroides, and Faecalibacterium in the gut, whereas it reduced the abundance of harmful bacteria such as Escherichia-shigella. Our findings may contribute to the development of new foods rich in dietary fiber to improve the digestive function of patients with multiple comorbidities.

Pyramiding Breeding of Low-Glutelin-Content Indica Rice with Good Quality and Resistance.

Low-glutelin-content rice, a type of functional rice with glutelin levels below 4%, is an essential dietary supplement for chronic kidney disease (CKD) patients. Developing low-glutelin-content rice varieties is crucial to catering to the growing CKD population. In this study, we aimed to create a new low-glutelin indica rice variety with excellent agronomic traits. To achieve this, we employed a combination of molecular-marker-assisted selection and traditional breeding techniques. The cultivars W3660, Wushansimiao (WSSM), and Nantaixiangzhan (NTXZ) were crossbred, incorporating the Lgc-1, Pi-2, Xa23, and fgr alleles into a single line. The result of this breeding effort was "Yishenxiangsimiao", a new indica rice variety that inherits the desirable characteristics of its parent lines. Yishenxiangsimiao (YSXSM) possesses not only a low glutelin content but also dual resistance to blast and bacterial blight (BB). It exhibits high-quality grains with a fragrant aroma. This new low-glutelin indica cultivar not only ensures a stable food supply for CKD patients but also serves as a healthy dietary option for the general public. We also performed RNA-seq of these rice varieties to investigate their internal gene expression differences. The YSXSM exhibited a higher biotic-resistance gene expression in comparison to NTXZ. In summary, we successfully developed a novel low-glutelin indica rice variety, "Yishenxiangsimiao", with superior agronomic traits. This rice variety addresses the dietary needs of CKD patients and offers a nutritious choice for all consumers.

Efficient breeding of low glutelin content rice germplasm by simultaneous editing multiple glutelin genes via CRISPR/Cas9

Chronic kidney disease (CKD) and phenylketonuria (PKU) patients need to eat rice with low glutelin content. Therefore, breeding low glutelin content rice varieties with high yield and delicious taste is one of the major goals of rice breeders due to the high demand for the product. In this study, we designed three sgRNAs targeting nine glutelin genes and generated nine T-DNA-free homozygous editing lines with reduced glutelin content compared with the wild-type due to simultaneous mutation(s) in 5–7 glutelin genes. The glutelin content of two lines is even significantly lower than that of the low glutelin content cultivar, LGC-1. Compared to the wild-type, these low glutelin lines showed similar agronomic traits, including yield components and viscosity properties, and can be used as new varieties or parental materials for further breeding.

α-globulin-rich rice cultivar, low glutelin content-1 (LGC-1), decreases serum cholesterol concentration in exogenously hypercholesterolemic rats.

Rice α-globulin has been reported to have serum cholesterol-lowering activity in rats. However, it is still unclear whether α-globulin exerts this effect when taken as one of the dietary components. In the present study, we investigated the effect of two cultivars of rice, low glutelin content (LGC)-1 and LGC-Jun, on reducing serum cholesterol in exogenously hypercholesterolemic (ExHC) rats. LGC-1 is enriched in α-globulin (10.6mg g-1 rice flour, which is an approximately 1.5 times higher α-globulin content than in Koshihikari a predominant rice cultivar in Japan), whereas LGC-Jun is a globulin-negative cultivar. ExHC rats, the model strain of diet-induced hypercholesterolemia, were fed 50% LGC-1 or LGC-Jun and 0.5% cholesterol-containing diets for 2 weeks, followed by measurement of cholesterol metabolism parameters in serum and tissues. Serum cholesterol and non-high-density lipoprotein cholesterol levels were significantly lower in the LGC-1 group compared to the LGC-Jun group. Cholesterol intestinal absorption markers, hepatic and serum levels of campesterol and β-sitosterol, and lymphatic cholesterol transport were not different between the two groups. Levels of 7α-hydroxycholesterol, an intermediate of bile acid synthesis, showed a downward trend in the livers of rats that were fed LGC-1 (P=0.098). There was a significant decrease in the hepatic mRNA expression of Cyp7a1 (a synthetic enzyme for 7α-hydroxycholesterol) in the LGC-1 group compared to the LGC-Jun group. Dietary LGC-1 significantly decreased serum cholesterol levels in ExHC rats. The possible mechanism for the cholesterol-lowering activity of LGC-1 is partial inhibition of bile acid and cholesterol synthesis in the liver. © 2021 Society of Chemical Industry.

低谷蛋白水稻N198的选育与高产栽培技术

N198是广东省农业科学院水稻研究所利用优质籼稻品种五山丝苗为母本，低谷蛋白粳稻品种W3660为父本杂交，经多代回交结合分子标记辅助选择选育出的一个低谷蛋白籼稻新品种。其丰产、稳产性好，米质优，抗稻瘟病，谷蛋白含量低于4%，可作为糖尿病肾病患者的主食或食疗辅助食品。本文简要介绍了N198的选育过程、特征特性以及高产栽培技术。 N198 is an new indica rice with low glutelin content which bred from the cross of Wushansimiao × W3660 by backcross breeding and marker-assisted selection by Rice Research Institute, Guangdong Academy of Agricultural Sciences. It has the characteristics of good and stable yielding, good quality, resistant to rice blast and more importantly with the glutelin content lower than 4%. So N198 is an ideal stable or therapeutic supplementary food for diabetic nephropathy patients. In this paper, we introduced the breeding process, characteristics and high yield cultivation techniques of N198.

The relationship between rice protein composition and nitrogen compounds in sake

The relationship between the protein composition of rice and nitrogen compounds (amino acids and oligo-peptides) in the produced sake were investigated using endosperm protein mutant rice (LGC-1, LGC-Jun, Kx433, QA28), sake rice (Yamadanishiki) and cooking rice (Nipponbare, Nihonmasari, Koshihikari). The total nitrogen concentration, amino acid concentration and most peptide peak areas determined by RP-HPLC and gel filtration chromatography of the produced sake were lower when sake was made from a low glutelin content rice mutant compared with other rice varieties. The concentration of nitrogen compounds in the sake positively correlated with the glutelin content of the highly milled rice grains used for sake production. Sake produced using a low glutelin content rice mutant is generally evaluated as having a light taste. Our findings suggest that nitrogen compounds (oligo-peptides and amino acids) derived from rice glutelin significantly contribute to the taste of sake.

High-level production of lactostatin, a hypocholesterolemic peptide, in transgenic rice using soybean A1aB1b as carrier

Hypercholesterolemia, a form of cardiovascular disease, is one of the leading causes of deaths worldwide. Lactostatin (Ile-Ile-Ala-Glu-Lys), derived from β-lactoglobulin in cow's milk, is a bioactive peptide with hypocholesterolemic activity higher than sitosterol, a known anti-hypercholesterolemic drug. Here, we successfully developed a transgenic rice accumulating a much higher level of lactostatin by inserting 29 IIAEK sequences into the structurally flexible (nonconserved) regions of soybean seed storage protein, A1aB1b, and introducing it into LGC-1 (low glutelin content mutant 1) as host variety. A1aB1b containing 29 lactostatins was expressed in the endosperm of rice seed cells by using seed specific promoters and sorted into novel compartments distinct from normal PB-I (ER-derived protein body) and PB-II (protein storage vacuoles). Transgenic rice seeds accumulated approximately 2 mg of lactostatins/g of dry seeds, which is relatively high compared with previous reports. Our findings suggest that the introduction of a high copy number of bioactive peptide into seed storage proteins as carrier is one of the effective means in producing higher amounts of bioactive peptides in rice.

Design and Validation of Two InDel Markers for Low Glutelin Content (Lgc1) Gene in Rice (Oryza sativa L.)

Rice with low glutelin content is quite effective as a kind of functional food for patients with kidney disease. It is of great importance to develop commercial rice varieties of low glutelin content. In recent years, Lgc1 gene, as an excellent genetic resource for rice varieties with low glutelin content, has been given more and more attention by breeders in functional rice breeding. To improve the precision of marker-assisted selection for Lgc1 gene in rice, we designed two pairs of functional markers for Lgc1 gene based on a 3.5 kb deletion fragment between two highly similar glutelin genes GluB4 and GluB5 in two rice mutants. Two InDel markers were designated and named In- Del-Lgc1-A and InDel-Lgc1-B, respectively. These markers were used to analyze 13 rice varieties and the F 2 segregation population derived from the cross of the low glutelin content rice variety W3660 and normal variety Nangjing46. The PCR results showed that according to the band types the homozygous genotype with low glutelin content, the heterozygous genotype, and the homozygous genotype with normal glutelin content could be clearly distinguished, which was completely consistent with the results of the protein analysis. Thus, these two InDel markers could be used to distinguish rice varieties with Lgc1 gene, and can also be used in marker-assisted selection.

Development of Simple Functional Markers for Low Glutelin Content Gene 1 ( Lgc1) in Rice ( Oryza sativa)

Rice with low glutelin content is suitable as functional food for patients affected by kidney failure. Low glutelin-content gene Lgc1 in rice has a 3.5-kb deletion between two highly similar glutelin genes GluB4 and GluB5, which locates on the short arm of chromosome 2. To improve the selection efficiency in low glutelin-content rice breeding, two molecular markers designated as InDel- Lgc1-1 and InDel- Lgc1-2 were developed to detect the low glutelin-content gene Lgc1. A double PCR detection indicated that combined use of the two markers could easily distinguish the genotypes of Lgc1 from different rice varieties. Therefore, as a simple and low-cost technique, the molecular marker could be widely used to identify different varieties with Lgc1 gene and applied in marker-assisted selection of low glutelin-content rice.

벼 등숙기간 중 글루테린 함량 변화에 따른 쌀의 수확적기 판정

The change of glutelin contents in rice grain during the maturity period was investigated to determine optimum rice harvesting time. The glutelin content was increased with increasing time after heading. In this study, eight of glutelin subunits were found. Among the glutelin subunits, 7208-subunit (MW, 35 kD) contents was significantly increased at 65 days after heading compared with 55 and 60 days after heading. 7405-subunit (MW, 50 kD) contents was steadily increased with time after heading. The results showed that at 55th day after heading would be optimum time for harvest to get the low glutelin content of rice grain.

Lack of 26 kDa globulin accompanies increased free amino acid content in rice ( Oryza sativa L.) grains

Seed nitrogen content, protein composition and free amino acid content were determined in rice mutant lines with altered storage protein composition and their parental cultivars. The Lgc1 gene, which causes low glutelin content and high content of 13 kDa prolamin and 26 kDa globulin, did not affect grain weight, nitrogen content, or free amino acid content. The glb1 gene, which lacks the 26 kDa globulin, did not affect grain weight or nitrogen content, but in mutant lines with glb1 gene the content of the major free amino acids was significantly (1.3–1.5 times) higher than those of their parental cultivars. These results suggest that absence of 26 kDa globulin is accompanied by an accumulation of a high level of free amino acids in rice grains.

Fine mapping and marker-assisted selection (MAS) of a low glutelin content gene in rice

Rice with low glutelin content is suitable as functional food for patients affected with diabetes and kidney failure. The fine mapping of the gene(s) responsible for low glutelin content will provide information regarding the distribution of glutelin related genes in rice genome and will generate markers for the selection of low glutelin rice varieties. Following an SDS-PAGE screen of rice germplasm from Taihu Valley of China, Japonica selection W3660 is identified to be a novel mutant characterized with low glutelin content. For fine mapping the mutant gene for low glutelin content, F2 and F3 populations were derived from a cross between W3660 and Jingrennuo. SDS-PAGE analysis of the total endosperm protein showed that the low glutelin content trait was controlled by a single dominant nuclear gene. Genetic mapping, using SSRs, located this gene to chromosome 2, in the region between SSR2-001/SSR2-004 and RM1358. The distances of the two markers to the target gene were 1.1 cM and 3.8 cM respectively. By semi-quantitative RT-PCR analysis, the transcripts of GluB4/GluB5 genes located within the region do not change. However, GluB5 gene located proximal to SSR2-001/SSR2-004 was specifically reduced. SSR profiles of seven Japonica varieties were compared with that of W3660 for loci in the relevant genetic region. The markers SSR2-004 and RM1358 were used for marker-assisted selection. The selection efficiencies of SSR2-004 and RM1358 were 96.8% and 92.7% respectively. This provides a standard starting point for the breeding of low glutelin content rice varieties in China.

遺伝子組換え低グルテリン米利用による酒質向上の可能性

Transgenic rice H 75 was generated by transformation with an antisense glutelin gene construct and grown in an ordinal paddy field in 1998 and 1999 under approval of the Ministry of Agriculture, Forestry and Fisheries. H 75 showed a 40% reduction of glutelin content in grains as well as an increase in prolamine content compared with the original variety, Tsukinohikari, in 1998 and with Tsukinohikari, another variety, Gohyakumangoku, and non-transformant, which was obtained as a revertant from H 75 at T1 generation by genetic segregation, in 1999. The total seed-protein content of H 75 did not significantly differ from that of the original variety, Tsukinohikari. Sake brewed from 70% polished H 75 grains contained 40% less amino acid content than sake brewed from 70% polished non-transgenic rice grains. A sake storage test showed that the sake from H 75 was lower in sake coloration, 3-deoxyglucosone content, and ultraviolet absorbance than sake from non-transformant and Gohya kumangoku during the entire test period of six months. The results suggest that a low-glutelin content of H 75 caused the sake to have less amino acid content and inhibited the deterioration of sake quality during storage.

A rice (Oryza sativa L.) mutant having a low content of glutelin and a high content of prolamine

Among the mutant lines of rice that have been selected for morphological characters, one line, NM67, was found to have a low content of glutelin and a higher content of prolamine in its seed protein than other Japanese cultivars. This mutant is a semi-dwarf and partially sterile line, and its leaves turn yellow before heading. Genetic analysis after backcross to the original cultivar, 'Nihonmasari', revealed the following: (1) the character of low glutelin content was always accompanied by the character of high prolamine content; (2) the low glutelin (and high prolamine) character seemed to be manifested by a single dominant gene; and (3) semi-dwarfness, low fertility and early yellowing leaf of the mutant, which might also be pleiotropy, were controlled by a single recessive gene independent of the gene for protein content. The protein character of NM67 was genetically separated from semi-dwarfness and low fertility, and a new line having low glutelin content and high prolamine content with normal morphological characters comparable to those of the original cultivar was obtained from the progenies of the cross. The possible use of this line as a low protein rice cultivar is discussed.