The altered pattern of amylose accumulation in the endosperm of low-amylose barley cultivars is attributable to a single mutant allele of granule-bound starch synthase I with a deletion in the 5′-non-coding region
The altered pattern of amylose accumulation in the endosperm of low-amylose barley cultivars is attributable to a single mutant allele of granule-bound starch synthase I with a deletion in the 5′-non-coding region
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DOI：
10.1104/pp.005454
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发表时间：
2002-09-01
期刊：
影响因子：
7.4
通讯作者：
Denyer, K
中科院分区：
文献类型：
--
作者：
Patron, NJ;Smith, AM;Denyer, K
对糯质大麦胚乳淀粉直链淀粉含量差异的原因进行了研究。大多数这类品种的成熟谷粒含有一些直链淀粉，尽管数量比野生型品种低得多。在这些低直链淀粉品种中，直链淀粉合成在籽粒发育中开始相对较晚。胚乳细胞外层的淀粉粒比中心的淀粉粒含有更多的直链淀粉。这种分布对应于颗粒结合淀粉合成酶I（GBSSI），这是更严重的减少量的胚乳中心比在外部细胞层，相对于野生型品种。大麦植株中的第二种GBSSI，GBSSIb，在胚乳中检测不到，并且不能解释低直链淀粉品种中直链淀粉的合成。低直链淀粉品种胚乳中GBSSI基因表达量的变化可能是由于该基因启动子和5 '端非翻译区的413 bp缺失所致。虽然这些品种是不同的地理来源，都进行了相同的缺失，这表明低直链淀粉品种有一个共同的蜡质祖先。记录表明，在中国可能的来源，第一次记录在世纪。另外两个糯性品种的家族在胚乳淀粉中没有检测到直链淀粉。这些无直链淀粉的品种是在世纪从化学诱变的野生型大麦群体中选出的。在这两种情况下，GBSSI基因中的1-bp改变完全消除了GBSSI活性。
Reasons for the variable amylose content of endosperm starch from waxy cultivars of barley (Hordeum vulgare) were investigated. The mature grains of most such cultivars contain some amylose, although amounts are much lower than in wild-type cultivars. In these low-amylose cultivars, amylose synthesis starts relatively late in grain development. Starch granules in the outer cell layers of the endosperm contain more amylose than those in the center. This distribution corresponds to that of granule-bound starch synthase I (GBSSI), which is more severely reduced in amount in the center of the endosperm than in the outer cell layers, relative to wild-type cultivars. A second GBSSI in the barley plant, GBSSIb, is not detectable in the endosperm and cannot account for amylose synthesis in the low-amylose cultivars. The change in the expression of GBSSI in the endosperm of the low-amylose cultivars appears to be due to a 413-bp deletion of part of the promoter and 5'-untranslated region of the gene. Although these cultivars are of diverse geographical origin, all carry this same deletion, suggesting that the low-amylose cultivars have a common waxy ancestor. Records suggest a probable source in China, first recorded in the 16th century. Two further families of waxy cultivars have no detectable amylose in the endosperm starch. These amylose-free cultivars were selected in the 20th century from chemically mutagenized populations of wild-type barley. In both cases, 1-bp alterations in the GBSSI gene completely eliminate GBSSI activity.