John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom.
PLoS One. 2012;7(3):e33234. doi: 10.1371/journal.pone.0033234. Epub 2012 Mar 22.
The timing of flowering during the year is an important adaptive character affecting reproductive success in plants and is critical to crop yield. Flowering time has been extensively manipulated in crops such as wheat (Triticum aestivum L.) during domestication, and this enables them to grow productively in a wide range of environments. Several major genes controlling flowering time have been identified in wheat with mutant alleles having sequence changes such as insertions, deletions or point mutations. We investigated genetic variants in commercial varieties of wheat that regulate flowering by altering photoperiod response (Ppd-B1 alleles) or vernalization requirement (Vrn-A1 alleles) and for which no candidate mutation was found within the gene sequence. Genetic and genomic approaches showed that in both cases alleles conferring altered flowering time had an increased copy number of the gene and altered gene expression. Alleles with an increased copy number of Ppd-B1 confer an early flowering day neutral phenotype and have arisen independently at least twice. Plants with an increased copy number of Vrn-A1 have an increased requirement for vernalization so that longer periods of cold are required to potentiate flowering. The results suggest that copy number variation (CNV) plays a significant role in wheat adaptation.
一年内开花的时间是影响植物生殖成功的一个重要适应特征，对作物产量至关重要。在驯化过程中，小麦（Triticum aestivum L.）等作物的开花时间已经被广泛调控，这使得它们能够在广泛的环境中高效生长。已经在小麦中鉴定出几个控制开花时间的主要基因，其突变等位基因具有插入、缺失或点突变等序列变化。我们研究了通过改变光周期反应（Ppd-B1 等位基因）或春化要求（Vrn-A1 等位基因）来调节开花的商业小麦品种中的遗传变异，而在基因序列中没有发现候选突变。遗传和基因组方法表明，在这两种情况下，改变开花时间的等位基因都增加了基因的拷贝数，并改变了基因表达。Ppd-B1 等位基因增加拷贝数会导致开花日中性表型提前出现，并且至少独立出现了两次。Vrn-A1 等位基因拷贝数增加的植物对春化的要求更高，因此需要更长的寒冷期才能促进开花。结果表明，拷贝数变异（CNV）在小麦适应中起着重要作用。
