水稻谷蛋白突变体的筛选及遗传分析

Screening and Genetic Analysis of Rice Glutelin Mutant

通过对国内外水稻品种种子的全蛋白分析 ,筛选到 3个谷蛋白突变材料。其中编号W36 6 0种子中 37～ 39kDa与 2 2～ 2 3kDa谷蛋白亚基的含量较普通水稻明显降低 ,而 13kDa醇溶蛋白多肽含量则大幅升高 ;W2 0 4和W379种子中 37～ 39kDa与 2 2～ 2 3kDa谷蛋白亚基的含量介于普通品种与W36 6 0之间 ,W379还具超大含量的 5 7kDa多肽 ,实验证明此多肽属谷蛋白成分。用W36 6 0和普通水稻栽培品种惊人糯 (Otorokimochi)构建了杂交群体。后代种子总蛋白SDS PAGE分析显示 ,低谷蛋白和高醇溶蛋白性状总是相伴出现 ;F1种子全部呈现低谷蛋白含量和高醇溶蛋白含量特性 ;F2 种子中呈现低谷蛋白和正常蛋白性状的比例约为 3∶1;从F3 种子分析推断出的F2 植株基因型 ,其低谷蛋白纯合型 ,杂合型和正常型的分离比例符合 1∶2∶1。表明 ,W36 6 0的低谷蛋白和高醇溶蛋白性状是由单显性基因控制 。

The contribution of rice as a protein source is important.Rice seed protein can be divided into four forms,glutelin (57 kDa,37～39 kDa,22～23 kDa),prolamine (13 kDa),albumin (16 kDa) and globulin (10 kDa,26 kDa) on its solubility.Glutelin is the major storage protein of rice and accounted for 80% of total protein found in the rice grain,the mature glutelin comprises an acidic (37～39 kDa) and an basic subunit (22～23 kDa) coming from a common precursor (57 kDa) by post transcriptional hydrolytic cleavage.Prolamine is the second important.Rice seed proteins localize in two types of protein bodies,PB Ⅰ,PB Ⅱ.PB Ⅰ containing prolamine is indigestible,whereas PB Ⅱ being rich in glutelin is digestible.The nutritional value of rice could thus be raised by improving its digestible protein glutelin content.On the other hand,the character of low digestible protein is also an important target of rice breeding.Low protein rice is required for the diet of patients with kidney disease.Three glutelin mutants,W3660,W204,W379,were found by screening 168 rice varieties through SDS PAGE analysis of the seeds total proteins.The amounts of 37～39 kDa and 22～23 kDa glutelin subunits were much lower and that of 13 kDa prolamine polypeptide was higher in W3660 seeds than in ordinary rice;The amounts of 37～39 kDa and 22～23 kDa glutelin subunits in W204 or W379 seeds were between those in W3660 and ordinary rice.Especially,in W379 seed,there was a large quantity of 57 kDa polypeptide.For characterizing the genetics of the glutelin mutant,the cross population between W3660 and Otorokimochi was constructed.SDS PAGE analysis of the progeny seed total proteins showed,low glutelin content was always accompanied by high prolamine content;all F 1 seeds had low glutelin and high prolamine content;the segregation of low glutelin and normal type in F 2 seeds was 3∶1;the genotypes of F 2 plants were deduced by the analysis of F 3 seeds,and amoung F 2 plants the ratio of homozygotes of low glutelin,heterozygotes of low glutelin and homozygotes of normal type was about 1∶2∶1.These results proved that the trait of low glutelin and high prolamine was controlled by a single dominant gene and could be inherited by its progeny.