Starch granule initiation and growth are altered in barley mutants that lack isoamylase activity
Starch granule initiation and growth are altered in barley mutants that lack isoamylase activity
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DOI：
10.1046/j.1365-313x.2002.01339.x
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发表时间：
2002-07-01
期刊：
影响因子：
7.2
通讯作者：
Denyer, K
中科院分区：
文献类型：
--
作者：
Burton, RA;Jenner, H;Denyer, K
两个大麦突变系Riso 17和Notch-2在籽粒中积累了植物糖原。与玉米和水稻的含糖突变体一样，这些积累植物糖原的大麦突变体在发育中的胚乳中缺乏异淀粉酶活性。突变体被证明是等位基因，并在异淀粉酶基因isa1中存在损伤，这是该酶缺失的原因。除了导致胚乳淀粉含量下降外，这些突变还对淀粉粒的结构、数量和起始时间产生了深远的影响。突变体中没有正常的A型和B型颗粒。与野生型相比，突变体的每个叶绿体含有更多的淀粉粒，特别是在Riso 17中，这导致了复合淀粉粒的出现。这些结果表明，除了抑制植物糖原的合成外，野生型胚乳中的异淀粉酶在决定淀粉粒的数量和形式方面也起着作用。
Two mutant lines of barley, Riso 17 and Notch-2, were found to accumulate phytoglycogen in the grain. Like the sugary mutants of maize and rice, these phytoglycogen-accumulating mutants of barley lack isoamylase activity in the developing endosperm. The mutants were shown to be allelic, and to have lesions in the isoamylase gene, isa1 that account for the absence of this enzyme. As well as causing a reduction in endosperm starch content, the mutations have a profound effect on the structure, number and timing of initiation of starch granules. There are no normal A-type or B-type granules in the mutants. The mutants have a greater number of starch granules per plastid than the wild-type and, particularly in Riso 17, this leads to the appearance of compound starch granules. These results suggest that, as well as suppressing phytoglycogen synthesis, isoamylase in the wild-type endosperm plays a role in determining the number, and hence the form, of starch granules.