Variation of Storage Proteins among Rice and Its Relationship with Eating Quality.

• Main Authors: Chien, Pei-Ju, 簡珮如
• Other Authors: Chun Chu, Huu-Sheng Lur
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/61399479162587501233

碩士 === 國立臺灣大學 === 農藝學系 === 85 === Storage proteins constitute at least 90％ of the total seed protein in rice grains. The storage proteins are generally categorized into four classes according to their solubility in various solvent. They are albumins, globulins, glutelins and prolamines. The relative contribution of each seed protein class can be influenced by genotype, growing conditions, and analytical methods employed. Besides, there are some correlation between storage proteins and eating quality. In the present study, protein quantitative analysis and reversed-phase high performance liquid chromatography ( RP-HPLC ) were used to investigate : 1) the variation of the content of each storage protein, as well as molecular diversity in rice cultivars, 2) the effect of cultivate environment to each of storage protein content, and 3) the relationship between storage protein content and eating quality. Finally, standard curves of storage protein for the near-infrared reflectance analysis (NIR) was constructed to efficiently determine the content of storage proteins. Forty - six rice cultivars including japonica、indica and glutinous types were tested to compare the content-variation of each storage proteins. The variation of prolamine molecular was further analyzed by RP-HPLC. Results showed that the content of the four kinds of storage proteins varied among cultivars. In general, total storage protein content of the indica type was higher than that of the japonica type. Among the four storage proteins, content of glutelins was the highest in every cultivar, but content of prolamines was only about 10 - 20％ of the glutelins. The difference between albumins and globulins contents among tested cultivars was insignificant. From the above results, the diversity of the prolamines and glutelins contents is significant among cultivars. In the year-round cultivation experiment, contents of albumins and globulins were not influenced by growing season, while the contents of prolamines and glutelins increased significantly with the lowering of temperature during grain filling stage. Usually, the curde protein content of the second crop rice is higher than that of the first crop rice,presumable be result of increment in glutelins and prolamines contents. Besides, the proteins compositions of each cultivar were also analyzed by RP-HPLC. The prolamine RP-HPLC profiles of tested cultivars were identical under different growing conditions, even the relative amplitude of peaks might be different. Thus, growing condition may possibly only influence the quantity, but not quality of the storage proteins. A significant negative correlation was found between the contents of prolamines and palatability index, especially in japonica type. However, the correlation was not found in the indica type. For both japonica and indica types, no significant correlation was found between the contents of glutelins and palatability index. It suggests that eating quality probably might not be affected by glutelins. Thus, how to control the content of prolamines in rice grains to aid the breeding of cultivar with a balanced nutrition and eating quality is worthy of further studies. In molecule analysis of storage proteins, prolamines showed the largest polymorphism among cultivars. The prolamine HPLC profiles of cultivars could be classified to five patterns. Within each pattern, the relative magnitude of peaks also varied with cultivars. Prolamine polymorphism was higher among indica type cultivars than among japonic cultivars. Almost every indica cultivar could be differentiated by its peak profile but this was not true for japonica cultivars. The results imply that the tested japonica cultivars have a narrower genetic basis at the storage protein level. The RP-HPLC profile can also be ultilized as a tool to identify the molecule nature of rice storage proteins, particularly for the indica type. In establishing standard curves of storage protein contents using NIR, the results showed that the multiple correlation coefficient (R2) was 0.8563 for albumins, 0.7574 for globulins, 0.9215 for prolmaines, and 0.9286 for glutelins. The results suggest that the storage protein content can be estimate by NIR, especially glutelins and prolamines. Nevertheless, input of more samples is necessary to amend and elevate the accuracy of the standard curves before they can be practically applied.