Complementation of sugary-1 phenotype in rice endosperm with the wheat isoamylase1 gene in supports a direct role for isoamylase1 amylopectin biosynthesis
Complementation of sugary-1 phenotype in rice endosperm with the wheat isoamylase1 gene in supports a direct role for isoamylase1 amylopectin biosynthesis
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DOI：
10.1104/pp.104.051359
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发表时间：
2005-01-01
期刊：
影响因子：
7.4
通讯作者：
Nakamura, Y
中科院分区：
文献类型：
--
作者：
Kubo, A;Rahman, S;Nakamura, Y
为了研究异淀粉酶1（isoamylase 1，ISA 1）在植物支链淀粉合成中的作用，将粗山羊草基因组DNA片段导入ISA 1缺陷型水稻（Oryza sativa）sugary-1突变系EM 914，使胚乳淀粉完全被植物糖原所取代。A. tauschii是小麦（Triticum aestivum）的D基因组供体，并且引入的片段有效地包括在D基因组上编码的小麦ISA 1基因（TalSA 1）。在表达TalSA 1的水稻胚乳中，植物糖原合成基本上被淀粉合成所取代，仅留下残留水平的植物糖原。存在的残留植物糖原的水平与TaISA 1蛋白的表达水平成反比，尽管在EM 914中降低的普鲁兰酶的水平恢复到与野生型相同的水平。小，但显着差异被发现在支链淀粉链长分布，糊化温度，和A型X-射线衍射图的淀粉从线表达TaISA 1相比，野生型水稻淀粉，虽然在前两个参数，效果是成比例的TaISA的表达水平。ISA 1表达水平对淀粉结构和性质的影响为ISA 1直接参与支链淀粉合成的观点提供了支持。
To examine the role of isoamylase1 (ISA1) in amylopectin biosynthesis in plants, a genomic DNA fragment from Aegilops tauschii was introduced into the ISA1-deficient rice (Oryza sativa) sugary-1 mutant line EM914, in which endosperm starch is completely replaced by phytoglycogen. A. tauschii is the D genome donor of wheat (Triticum aestivum), and the introduced fragment effectively included the gene for ISA1 for wheat (TalSA1) that was encoded on the D genome. In TalSA1-expressing rice endosperm, phytoglycogen synthesis was substantially replaced by starch synthesis, leaving only residual levels of phytoglycogen. The levels of residual phytoglycogen present were inversely proportional to the expression level of the TaISA1 protein, although the level of pullulanase that had been reduced in EM914 was restored to the same level as that in the wild type. Small but significant differences were found in the amylopectin chain-length distribution, gelatinization temperatures, and A-type x-ray diffraction patterns of the starches from lines expressing TaISA1 when compared with wild-type rice starch, although in the first two parameters, the effect was proportional to the expression level of TaISA. The impact of expression levels of ISA1 on starch structure and properties provides support for the view that ISA1 is directly involved in the synthesis of amylopectin.