Shcherban Andrey B, Salina Elena A
The Federal Research Center "Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences", Lavrentiev ave. 10, Novosibirsk, 630090, Russia.
BMC Plant Biol. 2017 Nov 14;17(Suppl 1):188. doi: 10.1186/s12870-017-1129-9.
The key gene in genetic system controlling the duration of the vegetative period in cereals is the VRN1 gene, whose product under the influence of low temperature (vernalization) promotes the transition of the apical meristem cells into a competent state for the development of generative tissues of spike. As early genetic studies shown, the dominant alleles of this gene underlie the spring forms of plants that do not require vernalization for this transition. In wheat allopolyploids various combinations of alleles of the VRN1 homoeologous loci (VRN1 homoeoalleles) provide diversity in such important traits as the time to heading, height of plants and yield. Due to genetical mapping of VRN1 loci it became possible to isolate the dominant VRN1 alleles and to study their molecular structure compared with the recessive alleles defining the winter type of plants. Of special interest is the process of divergence of VRN1 loci in the course of evolution from diploid ancestors to wheat allopolyploids of different levels of ploidy.
Molecular analysis of VRN1 loci allowed to establish that various dominant alleles of these loci appeared as a result of mutations in two main regulatory regions: the promoter and the first intron. In the diploid ancestors of wheat, especially, in those of A- genome (T. boeoticum, T. urartu), the dominant VRN1 alleles are rare in accordance with a limited distribution of spring forms in these species. In the first allotetraploid wheat species including T. dicoccoides, T. araraticum (T. timopheevii), the spring forms were associated with a new dominant alleles, mainly, within the VRN-A1 locus. The process of accumulation of new dominant alleles at all VRN1 loci was significantly accelerated in cultivated wheat species, especially in common, hexaploid wheat T. aestivum, as a result of artificial selection of spring forms adapted to different climatic conditions and containing various combinations of VRN1 homoeoalleles.
This mini-review summarizes data on the molecular structure and distribution of various VRN1 homoeoalleles in wheat allopolyploids and their diploid predecessors.
在谷类作物中，控制营养生长期时长的遗传系统中的关键基因是VRN1基因，其产物在低温（春化作用）影响下可促进顶端分生组织细胞转变为能发育成穗部生殖组织的状态。早期遗传学研究表明，该基因的显性等位基因是植物春性类型的基础，这类植物在这种转变过程中不需要春化作用。在小麦异源多倍体中，VRN1同源位点（VRN1同源等位基因）的各种等位基因组合在抽穗时间、株高和产量等重要性状上表现出多样性。由于对VRN1位点进行了遗传定位，使得分离显性VRN1等位基因并研究其与决定植物冬性类型的隐性等位基因相比的分子结构成为可能。特别令人感兴趣的是VRN1位点在从二倍体祖先到不同倍性水平的小麦异源多倍体的进化过程中的分化过程。
对VRN1位点的分子分析表明，这些位点的各种显性等位基因是由两个主要调控区域（启动子和第一个内含子）的突变产生的。在小麦的二倍体祖先中，尤其是A基因组（一粒小麦、乌拉尔图小麦）的祖先中，由于这些物种中春性类型分布有限，显性VRN1等位基因很少见。在包括野生二粒小麦、阿拉拉特小麦（提莫菲维小麦）在内的首个异源四倍体小麦物种中，春性类型主要与VRN - A1位点内的一个新的显性等位基因相关。由于人工选择适应不同气候条件且含有VRN1同源等位基因各种组合的春性类型，在栽培小麦物种中，尤其是在普通六倍体小麦普通小麦中，所有VRN1位点上新的显性等位基因的积累过程显著加速。
本综述总结了关于小麦异源多倍体及其二倍体祖先中各种VRN1同源等位基因的分子结构和分布的数据。
