Genetic modification of amylopectin fine structure in endosperm starch of rice

水稻胚乳淀粉中支链淀粉精细结构的遗传改造

基本信息

批准号：
14206003
负责人：
SATOH Hikaru
金额：
$ 26.12万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

We obtained newly more than 1,200 mutants modifying amylopectin fine structure by MNU treatment. At least 10 independent enzymes were participated in amylopectin biosynthesis, those are, 5 kinds of SSS, 3 of BE and 2 of DBE. The mutations of genes encoding respective enzymes involved in amylopectin biosynthesis were isolated,BE IIb mutation decreased specifically the short chains with less than DP 17 and increased longer chains with more than DP19. Contrarily, the amylopectin of BE I mutant was characterized by the significant decrease in long chains with more than DP 38 and the short chains with DP 12 to 23, and marked increase in short chains with less than DP12. The endosperm starch from the BE I mutant had the lower onset temperature for thermo-gelatinization. By contrast, BE IIb mutant showed the higher onset temperature for thermo-gelatinization. These findings indicate that the genetic modification of amylopectin fine structure is responsible for changes in physicochemical and rheological properties of the starch. The results support the view that alterations in amylopectin structure, in particular in short chains within clusters, might play a critical role in the rheological properties of starch. It is, therefore, likely that genetic modification of the gene for BEs will lead to the synthesis of novel types of starch as new materials for the foods and starch industries. ISA deficient mutations increased the short chains and decreased long chains dramatically. Rheological properties of DBE mutant are characterized by extremely lower viscosity in contrast to that of wild type. SS mutations altered the fine structure of amylopectin and their rheological properties as well as BE and DBE mutations. These results imply that amylopectin fine structure is important in determination of rheological properties of starch and genetic modification lead to the development of novel starch in rice.

通过MNU处理，我们新获得了1200多个改变支链淀粉精细结构的突变体。至少有10种独立的酶参与支链淀粉的生物合成，它们是5种SSS、3种BE和2种DBE。分离出编码参与支链淀粉生物合成的各个酶的基因突变，BE IIb突变特异性地减少了DP 17以下的短链，并增加了DP19以上的长链。而BE I突变体支链淀粉的特点是DP 38以上的长链和DP 12～23的短链显着减少，DP12以下的短链显着增加。 BE I 突变体的胚乳淀粉具有较低的热糊化起始温度。相比之下，BE IIb 突变体显示出更高的热糊化起始温度。这些发现表明支链淀粉精细结构的遗传修饰导致了淀粉的理化和流变特性的变化。结果支持这样的观点：支链淀粉结构的改变，特别是簇内短链的改变，可能在淀粉的流变特性中发挥关键作用。因此，BE 基因的遗传修饰可能会导致新型淀粉的合成，作为食品和淀粉工业的新材料。 ISA 缺陷突变显着增加了短链并减少了长链。 DBE突变体的流变特性的特点是与野生型相比粘度极低。 SS 突变以及 BE 和 DBE 突变改变了支链淀粉的精细结构及其流变特性。这些结果表明支链淀粉的精细结构对于确定淀粉的流变特性非常重要，并且遗传修饰导致了大米中新型淀粉的开发。