Burton Rachel A, Jenner Helen, Carrangis Luke, Fahy Brendan, Fincher Geoffrey B, Hylton Chris, Laurie David A, Parker Mary, Waite Darren, van Wegen Sonja, Verhoeven Tamara, Denyer Kay
Department of Plant Science, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.
Plant J. 2002 Jul;31(1):97-112. doi: 10.1046/j.1365-313x.2002.01339.x.
Two mutant lines of barley, Risø 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 Risø 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.
人们发现大麦的两个突变系Risø 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。研究表明，这些突变体是等位基因，并且在异淀粉酶基因isa1中存在损伤，这导致了该酶的缺失。这些突变不仅导致胚乳淀粉含量降低，还对淀粉粒的结构、数量和起始时间产生了深远影响。突变体中没有正常的A型或B型颗粒。与野生型相比，突变体每个质体中的淀粉粒数量更多，特别是在Risø 17中，这导致了复合淀粉粒的出现。这些结果表明，野生型胚乳中的异淀粉酶除了抑制植物糖原合成外，还在决定淀粉粒的数量以及形态方面发挥作用。
