Natural variation in rice starch synthase IIa affects enzyme and starch properties.
Natural variation in rice starch synthase IIa affects enzyme and starch properties.
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DOI：
10.1071/fp04009
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发表时间：
2004-08
期刊：
影响因子：
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通讯作者：
T. Umemoto;N. Aoki;Hong-Xuan Lin;Yasunori Nakamura;N. Inouchi;Youichiro Sato;M. Yano;H. Hirabayashi;S. Maruyama
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文献类型：
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作者：
T. Umemoto;N. Aoki;Hong-Xuan Lin;Yasunori Nakamura;N. Inouchi;Youichiro Sato;M. Yano;H. Hirabayashi;S. Maruyama
水稻淀粉合成酶Ⅱ a（SSIIa）的自然变异使用近等基因系（NIL）表征。SSIIa是一个候选人的alk基因调节水稻籽粒碱分解，因为这两个基因的遗传定位在同一个位置上的染色体6和相关的淀粉特性。在这项研究中，我们报告说，碱敏感品种日本晴缺乏SSIIa活性的胚乳。然而，活性检测与近等离子体具有耐碱性Kasalath的alk等位基因。SSIIa蛋白甚至在日本晴胚乳中也存在，但在胚乳的乳熟期与淀粉粒不相关。对65个栽培稻品种和4个栽培稻野生近缘种的日本晴和Kasalath的SSIIa cDNA序列进行了3个单核苷酸多态性（SNPs）的基因型分析。所获得的结果解释了两个氨基酸残基的潜在重要性的淀粉协会的水稻SSIIa。对支链淀粉的β-极限糊精的链长分布的分析表明，在没有SSIIa活性的情况下，A-链（没有分支的短链）的相对数量增加，而B1-链（有分支的短链）的相对数量减少。这表明，由于SSIIa缺陷，短A链不能达到足够的长度，使分支酶作用于它们以产生B1链。
The natural variation in starch synthase IIa (SSIIa) of rice (Oryza sativa L.) was characterised using near-isogenic lines (NILs). SSIIa is a candidate for the alk gene regulating the alkali disintegration of rice grains, since both genes are genetically mapped at the same position on chromosome 6 and related to starch properties. In this study, we report that the alkali-susceptible cultivar Nipponbare lacked SSIIa activity in endosperm. However, the activity was detected with NILs having the alk allele of alkali-tolerant Kasalath. SSIIa protein was present even in Nipponbare endosperm, but it was not associated with starch granules at the milky stage of endosperm. Three single-nucleotide polymorphisms (SNPs) predicting amino acid substitutions existed between the cDNA sequences of SSIIa of Nipponbare and Kasalath were genotyped with 65 rice cultivars and four wild relatives of cultivated rice. The results obtained explain the potential importance of two of the amino acid residues for starch association of rice SSIIa. An analysis of the chain-length distribution of β-limit dextrin of amylopectin showed that without SSIIa activity, the relative number of A-chains (the short chains without branches) increased and that of B1-chains (the short chains with branches) decreased. This suggests that, given the SSIIa defect, short A-chains could not reach a sufficient length for branching enzymes to act on them to produce B1-chains.