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

Rice embryos are rich in high-quality protein, lipid, vitamins and minerals, representing the most important nutritional part of brown rice. However, the molecular mechanism of rice embryo development is poorly understood. In this study, two rice cultivars with contrasting embryo size (the giant embryo cultivar Dapeimi and the normal embryo cultivar 187R) were used to explore excellent genes controlling embryo size, and the developed near-isogenic lines (NILs) (NIL-D, which has the giant embryo phenotype, and its matching line, NIL-X) were used to explore transcript and metabolic properties in the earlier maturation stage of giant embryo development under natural conditions. The map-based cloning results demonstrated that Dapeimi is a novel allelic mutant of the rice GIANT EMBRYO (GE) gene, and the functional mutation site is a single cytosine deletion in the exon1. A total of 285 differentially accumulated metabolites (DAMs) and 677 differentially expressed genes (DEGs) were identified between NIL-D and NIL-X. The analysis of DAMs indicated that plants lacking GE mainly promoted energy metabolism, amino acid metabolism, and lipid metabolism pathways in the rice embryo. Pearson correlation coefficient showed that 300 pairs of gene-metabolites were highly correlated. Among them, OsZS_02G0528500 and OsZS_12G0013700 were considered to be key genes regulating L-Aspartic acid and L-Tryptophan content during rice giant embryo development, which are promising to be good candidate genes to improve rice nutrition. By analyzing rice embryo development through a combination of strategies, this research contributes to a greater understanding of the molecular mechanism of rice embryo development, and provides a theoretical foundation for breeding high-nutrition varieties.

Oral Administration of Germinated, Pigmented, Giant Embryo Rice (Oryza sativa L. cv. Keunnunjami) Extract Improves the Lipid and Glucose Metabolisms in High-Fat Diet-Fed Mice

Obesity is a significant risk factor for chronic diseases. The effect of ethanol extract from germinated Keunnunjami, blackish-purple rice with a giant embryo, compare to ordinary brown rice, on the body weight and lipid and glucose metabolism in high-fat diet-fed mice was analyzed. Mice were fed with a high-fat diet-fed for 3 weeks and then orally administered with either distilled water (HF) or extract (0.25%, w / w ) from brown, germinated brown, Keunnunjami, and germinated Keunnunjami rice for 4 weeks. Control mice were fed with a normal diet and orally administered with distilled water. The HF group showed markedly higher body weight and triglyceride, cholesterol, fatty acid, glucose, and insulin levels than the control group. However, the oral administration of rice extracts ameliorated this high-fat diet-induced obesity, hyperlipidemia, and hypoglycemia through the modulation of adipokine production, lipogenic and glucose-regulating enzyme activities, and mRNA expression of genes associated with lipid and glucose metabolism. The germinated Keunnunjami extract exhibited greater hypolipidemic, hypoglycemic, and body weight-lowering effects than the other rice extracts. The results demonstrated that germination could further enhance the physiological properties of rice and that germinated Keunnunjami extract has a strong therapeutic potential against high-fat diet-induced obesity, hyperlipidemia, and hyperglycemia.

Study on the Chalkiness Character of Giant Embryo Rice and Observation on Its Microstructure in Grains

Grain chalkiness greatly affects the grain appearance and milling, eating, cooking, and nutritional qualities, thus it is one of the most important traits of grain qualities. Based on the study of chalkiness characters in endosperm of different giant embryo rice, the relationship between the differences of chalkiness characters in endosperm of different giant embryo rice and the morphological structure, arrangement and development of starch granules in endosperm was clarified, which will lay a solid foundation for further revealing the formation mechanism of chalkiness characters in giant embryo rice and cultivating excellent new varieties of giant embryo rice. In this study, the chalkiness of endosperm (including chalkiness rate, chalkiness degree and chalkiness area) of 16 different rice varieties were investigated and analyzed. The results showed that the chalkiness of endosperm was closely related to the morphological structure and arrangement of starch granules in endosperm cells of different kinds of giant embryo rice, and there were significant differences between the chalkiness of different parts of the same giant embryo rice and the morphological structure and arrangement of starch granules in endosperm cells. Therefore, the results of this study will provide important information for the improvement of quality characters and the breeding of new rice varieties.

Detection and Analysis of Mineral Elements in Giant Embryo Rice

Mineral elements are essential micronutrients necessary to constitute human tissue and maintain normal physiological functions. Micronutrient deficiencies are an important issue currently faced in the world. The best strategy to solve this problem is to breed special functional types of rice varieties rich in trace elements (special rice for short). A special type of rice that can produce rich nutrients. In order to explore the nutritional value of giant embryo rice, the contents of 17 mineral elements ((K, Ca, Fe, Se, Zn, Cu, Na, Mn, Mg, Ni, Cr, Co, Pb, As, Cd, Ag, Al)) in 5 kinds of giant embryo rice (white giant embryo, giant japonica-GB-12, giant japonica-GB-11 and giant japonica-GB-5, giant japonica-GB-1) were detected by inductively coupled plasma mass spectrometry. After comparison with ordinary rice, it was found that the content of the same mineral element in different samples has a large variation, suggesting that different rice varieties have different absorption, transformation and storage efficiency of the same element; different giant embryo brown rice in some mineral elements (such as Cr, Ni, Cu and Zn) are extremely low in content and almost undetectable. Meanwhile, the brown rice of giant embryo rice has a more powerful enrichment effect on some mineral elements, which means that embryo rice has a unique advantage in cultivating new rice varieties with special functions rich in minerals.