Laboratory of Molecular-Genetic Systems, Institute of Cytology and Genetics, Novosibirsk 90, Russian Federation.
BMC Plant Biol. 2010 Aug 11;10:168. doi: 10.1186/1471-2229-10-168.
Variability of the VRN1 promoter region of the unique collection of spring polyploid and wild diploid wheat species together with diploid goatgrasses (donor of B and D genomes of polyploid wheats) were investigated. Accessions of wild diploid (T. boeoticum, T. urartu) and tetraploid (T. araraticum, T. timopheevii) species were studied for the first time.
Sequence analysis indicated great variability in the region from -62 to -221 nucleotide positions of the VRN1 promoter region. Different indels were found within this region in spring wheats. It was shown that VRN1 promoter region of B and G genome can also contain damages such as the insertion of the transposable element.Some transcription factor recognition sites including hybrid C/G-box for TaFDL2 protein known as the VRN1 gene upregulator were predicted inside the variable region. It was shown that deletions leading to promoter damage occurred in diploid and polyploid species independently. DNA transposon insertions first occurred in polyploid species. At the same time, the duplication of the promoter region was observed in A genomes of polyploid species.
We can conclude that supposed molecular mechanism of the VRN1 gene activating in cultivated diploid wheat species T. monococcum is common also for wild T. boeoticum and was inherited by T. monococcum. The spring polyploids are not related in their origin to spring diploids. The spring T. urartu and goatgrass accessions have another mechanism of flowering activation that is not connected with indels in VRN1 promoter region. All obtained data may be useful for detailed insight into origin of spring wheat forms in evolution and domestication process.
研究了春性多倍体和野生二倍体小麦特有集合体的 VRN1 启动子区域的变异性，以及二倍体山羊草（多倍体小麦的 B 和 D 基因组供体）。首次研究了野生二倍体（T. boeoticum、T. urartu）和四倍体（T. araraticum、T. timopheevii）物种的材料。
序列分析表明，VRN1 启动子区域从-62 到-221 核苷酸位置的区域存在很大的变异性。在春小麦中发现了该区域内的不同缺失。结果表明，B 和 G 基因组的 VRN1 启动子区域也可能包含损伤，如转座元件的插入。在可变区域内预测到了包括 TaFDL2 蛋白的杂交 C/G 盒在内的一些转录因子识别位点，已知 TaFDL2 蛋白是 VRN1 基因的上调因子。结果表明，导致启动子损伤的缺失在二倍体和多倍体物种中独立发生。DNA 转座子插入首先发生在多倍体物种中。同时，在多倍体物种的 A 基因组中观察到启动子区域的重复。
我们可以得出结论，假定在栽培二倍体小麦物种 T. monococcum 中激活 VRN1 基因的分子机制也适用于野生 T. boeoticum，并由 T. monococcum 遗传。春性多倍体与春性二倍体在起源上没有关系。春性 T. urartu 和山羊草材料具有另一种开花激活机制，与 VRN1 启动子区域的插入无关。所有获得的数据可能有助于深入了解春小麦形式在进化和驯化过程中的起源。
