Antisense inhibition of isoamylase alters the structure of amylopectin and the physicochemical properties of starch in rice endosperm
Antisense inhibition of isoamylase alters the structure of amylopectin and the physicochemical properties of starch in rice endosperm
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DOI：
10.1093/pcp/pcg079
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发表时间：
2003-06-01
影响因子：
4.9
通讯作者：
Nakamura, Y
中科院分区：
文献类型：
--
作者：
Fujita, N;Kubo, A;Nakamura, Y
这是利用反义技术调控异淀粉酶1基因改变植物支链淀粉结构和淀粉性质的首次报道。异淀粉酶1蛋白在水稻胚乳中减少约94%，将支链淀粉转变为水不溶性的改性支链淀粉和水溶性的聚葡聚糖（WSP）。与野生型支链淀粉相比，改性后的支链淀粉具有更多的聚合度为5-12的短链，而它们的分子大小相似。WSP在结构上类似于异淀粉酶缺陷的sugary-1突变体中的植物糖原，占反义胚乳中总α-聚葡聚糖的约16%，并且与sugary-1突变体不同，WSP分布在整个胚乳中。异淀粉酶活性的降低使淀粉的糊化温度从54 ℃降低到43 ℃，淀粉的粘度、X-射线衍射图谱和颗粒形态发生了改变。支链淀粉酶，另一种类型的淀粉脱支酶，在反义胚乳中的活性与野生型相似，而它是缺乏糖-1突变体。这些结果表明，异淀粉酶1是水稻胚乳支链淀粉合成所必需的，异淀粉酶活性的改变是改变淀粉理化性质和颗粒结构的有效手段。
This is the first report on regulation of the isoamylase1 gene to modify the structure of amylopectin and properties of starch by using antisense technology in plants. The reduction of isoamylase1 protein by about 94% in rice endosperm changed amylopectin into a water-insoluble modified amylopectin and a water-soluble polyglucan (WSP). As compared with wild-type amylopectin, the modified amylopectin had more short chains with a degree of polymerization of 5-12, while their molecular sizes were similar. The WSP, which structurally resembled the phytoglycogen in isoamylase-deficient sugary-1 mutants, accounted for about 16% of the total alpha-polyglucans in antisense endosperm, and it was distributed throughout the whole endosperm unlike in sugary-1 mutant. The reduction of isoamylase activity markedly lowered the gelatinization temperature from 54 to 43degreesC and the viscosity, and modified X-ray diffraction pattern and the granule morphology of the starch. The activity of pullulanase, the other type of starch debranching enzyme, in the antisense endosperm was similar to that in wild-type, whereas it is deficient in sugary-1 mutants. These results indicate that the isoamylase1 is essential for amylopectin biosynthesis in rice endosperm, and that alteration of the isoamylase activity is an effective means to modify the physicochemical properties and granular structure of starch.