Differential regulation at the wx locus of rice

水稻中的蜡质(Wx)基因是一种主要的淀粉颗粒结合蛋白，称为Wx蛋白，具有很好的遗传特性。我们以前的工作表明，除了Wx外，在Wx基因座上至少还有两个非糯性等位基因，它们以不同的方式调节基因产物和直链淀粉的数量。本研究旨在更深入地了解Wx基因座的等位基因分化对非糯稻品种直链淀粉含量差异的重要性。结果证实，在所测试的自然发生的变异中，直链淀粉含量主要由Wx基因座上的等位基因变化决定。此外，温度、改性剂和基因剂量对基因产物量的影响与直链淀粉含量的影响相似。这些效应预计会导致直链淀粉含量在分离群体中成为多基因性状，就像在水稻中经常报道的那样，尽管直链淀粉含量只是由Wx蛋白的数量控制。文中还讨论了Wx基因座的等位基因分化与基因调控的进化意义。

The waxy (wx) locus in rice, which specifies a major starchgranule-bound protein called Wx protein, is genetically well characterized. Our previous works revealed that in addition to wx, there are at least two nonwaxy alleles at the wx locus which regulate the amounts of the gene product as well as amylose in different ways. The present study was carried out to get more insights on to what extent the allelic differentiation at the wx locus is important for diversification in amylose content observed among nonwaxy rice cultivars. The results confirmed that among naturally occurring variants tested, amylose content is mainly determined by the allelic changes at the wx locus. In addition, the amount of the gene product was affected by effects of temperatures, modifiers and the gene dosage in a similar manner which the amylose content was affected. Those effects were expected to lead the amylose content to a polygenic trait in segregating populations as often reported in rice, even though the amylose content was simply controlled by the amount of Wx protein. The allelic differentiation at the wx locus was also discussed in relation to the evolutionary significances of the gene regulation.