A single base change altered the regulation of the Waxy gene at the posttranscriptional level during the domestication of rice
A single base change altered the regulation of the Waxy gene at the posttranscriptional level during the domestication of rice
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DOI：
10.1093/oxfordjournals.molbev.a026013
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发表时间：
1998-08-01
影响因子：
10.7
通讯作者：
Sano, Y
中科院分区：
文献类型：
--
作者：
Hirano, HY;Eiguchi, M;Sano, Y
水稻蜡质（wx）基因座具有两个功能等位基因，Wx（a）和Wx（B），其由在成熟种子中积累的基因产物（称为Wx蛋白）的量的巨大差异来定义。为了阐明这种差异背后的分子机制，并确定在水稻进化过程中引起Wx基因调控改变的碱基变化，我们确定了Wx等位基因调控区的核苷酸序列，并分析了它们的功能，在一个瞬时检测系统使用水稻原生质体。所有Wx（a）等位基因均来自籼稻（Oryza sativa Indica）、籼稻（O. rufipogon和O. glaberrima在第一内含子的5'剪接点处具有正常的GT序列，代表Wx转录物在胚乳中的高表达水平和原生质体中的高β-葡萄糖醛酸酶（GUS）活性。另一方面，两株O. Sativa Japonica在5'剪接点处具有TT，代表成熟转录本的低表达水平和低GUS活性。北方印迹分析也表明，较大的转录本，由未剪接的第一内含子，是密切相关的Wx（B）等位基因的功能。这些结果表明，在5'剪接点处的单个碱基变化导致低效剪接，并且因此降低了Wx（B）等位基因中的成熟转录物水平和GUS活性。Wx（B）等位基因在O.日本唾液可能与O. rufipogon，它的野生祖先，通过这种突变，因此，一个单一的碱基变化，改变了Wx基因的调控在转录后水平可能发生在水稻的驯化。
The rice waxy (wx) locus has two functional alleles, Wx(a) and Wx(b), which are defined by a large difference in the amount of the gene product, called Wx protein, that accumulates in mature seeds. To elucidate the molecular mechanism underlying this difference and to identify the base change causing the alteration of the regulation of the Wx gene during rice evolution, we determined the nucleotide sequences of the regulatory region of Wx alleles and analyzed their function in a transient assay system using rice protoplasts. All Wx(a) alleles from Oryza sativa Indica, O. rufipogon, and O. glaberrima have a normal sequence of GT at the 5' splice junction of the first intron, representing a high expression level of the Wx transcripts in the endosperm and a high beta-glucuronidase (GUS) activity in protoplasts. On the other hand, Wx(b) alleles from two strains of O. sativa Japonica have TT at the 5' splice junction, representing a low expression level of the mature transcripts and a low GUS activity. Northern blot analysis also indicated that a larger transcript, consisting of the unspliced first intron, is closely correlated with the function of the Wx(b) allele. These results suggest that a single base change at the 5' splice junction causes inefficient splicing and, as a result, reduces the level of mature transcript and the GUS activity in the Wx(b) allele. The Wx(b) allele in O. saliva Japonica may have been differentiated from the Wx(a) allele of O. rufipogon, its wild progenitor, by this mutation, and, therefore, a single base change that has altered the regulation of the Wx gene at the posttranscriptional level probably occurred during the domestication of rice.