Chalkiness characters affect not only the grain appearance,milling,eating and cooking qualities but also the grain nutritional quality in rice,thus it is one of the most important traits in rice. It is very important for us to investigate the relation of the chalkiness formation and the development of endosperm structure and starch granule of different rice varieties. Here,we have investigated the chalkiness characters such as chalkiness rate,chalkiness degree and chalkiness area in 15 japonica rice varieties from southern Henan. Furthermore,the endosperm structure and starch granules of rice grain were also observed with scanning electron microscope. The results showed that the 15 japonica varieties have a significantly linear relationship between the chalkiness rate and chalkiness degree. Among the varieties,the biggest difference is the chalkiness rate,the second is the chalkiness area,and the last is the chalkiness degree. Moreover,there is a certain correlation between the distribution of starch granules,the arrangement of endosperm cells and the occurrence of grain chalkiness in the different rice varieties. For the same variety,the starch granules of chalky and non-chalky grains have obvious difference,while the starch granules from the transparent part of chalky rice and non-chalky rice do not have significant difference. The results would provide useful references for the improvement of grain quality in rice.
Enhancing the nutritional quality of food crops is a way to improve human nutrition and health. Grain protein content （ GPC ） is an important nutritional quality trait for rice and many other crops. Therefore, it will be very significant to increase GPC and improve rice quality. This paper mainly reviewed the genetic studies GPC in rice, mapping and cloning of QTLs and genes associated with GPC. However, little is known about the molecular mechanism and gene function related to GPC in rice. Thus, here we put forward the genetic strategy by gene pyramiding or molecular marker assisted selection to improve GPC and nutritional quality in rice. This review could provide important information for genetic improvement of grain nutritional quality of rice.
[ Objective] A method was developed for the analysis of main metabolites in aromatic rice seeds by gas chromatography-mass spectrometry （GC-MS）. [ Method] The main metabolites in seeds of 9 different aromatic rice varieties were compared and analyzed with two methods. Method 1 ： the compound was extracted by the mixture of anhydrous ethanol and methylene chloride （ WV = 1：1 ） at 60 ℃ for 3 h in water bath; the extract was isolated and detected by gas chromatography-mass spectrometry using HP-5 capillary column with scan monitoring mode. Method 2： the main metabolites in aromatic rice seeds were detected using headspaee solid phase micro-extraction and gas chromatography mass spectrometry （GC-MS）. [ Result ] Fifteen types of common metabolites were found in 9 different aromatic rice varieties. Method 1 was more effective than method 2 in detecting the main metabolites in aromatic rice seeds. [ Conclusion] This study provides an important reference for clarifying the metabolic pathway of main metabolites in aromatic rice and lays the foundation for further rice breeding.
