Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat
Large deletions within the first intron in VRN-1 are associated with spring growth habit in barley and wheat
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DOI：
10.1007/s00438-004-1095-4
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发表时间：
2005-03-01
影响因子：
3.1
通讯作者：
Dubcovsky, J
中科院分区：
文献类型：
--
作者：
Fu, DL;Szucs, P;Dubcovsky, J
小麦和大麦的广泛适应性部分归因于它们灵活的生长习性，春季形态是从祖先的冬季生长习性不断进化而来的。在二倍体小麦和大麦中，生长习性由 VRN-1 和/或 VRN-2 基因座的等位基因变异决定，而在多倍体小麦物种中，它主要由 VRN-1 的等位基因变异决定。春季生长习性的显性 Vrn-A1 等位基因经常与二倍体小麦启动子区和普通小麦 A 基因组中的突变相关。然而，几个显性 Vrn-A1、Vrn-B1、Vrn-D1（普通小麦）和 Vrn-H1（大麦）等位基因相对于各自的隐性等位基因，在启动子区域没有表现出多态性。在这项研究中，我们对这些种质的完整 VRN-1 基因进行了测序，发现它们的第一个内含子内都有大的缺失，这些缺失在 4 kb 的区域中重叠。此外，4 kb 区域内的 2.8 kb 片段在不同隐性等位基因之间显示出高度的序列保守性。这些缺失的 PCR 标记显示，所有具有已知 Vrn-B1 和 Vrn-D1 等位基因的种质以及之前显示 VRN-A1 启动子区域不存在多态性的 51 个六倍体春小麦种质中都存在类似的缺失。 24 个四倍体小麦种质在 VRN-A1 内含子 1 中具有类似的缺失。我们假设 2.8 kb 的保守区域包含对春化要求很重要的调控元件。 VRN-H2 和 VRN-H1 等位基因之间的上位相互作用以及内含子 1 缺失表明，缺失区域可能包括一个由大麦 VRN-H2 基因产物介导的开花抑制的识别位点。
The broad adaptability of wheat and barley is in part attributable to their flexible growth habit, in that spring forms have recurrently evolved from the ancestral winter growth habit. In diploid wheat and barley growth habit is determined by allelic variation at the VRN-1 and/or VRN-2 loci, whereas in the polyploid wheat species it is determined primarily by allelic variation at VRN-1. Dominant Vrn-A1 alleles for spring growth habit are frequently associated with mutations in the promoter region in diploid wheat and in the A genome of common wheat. However, several dominant Vrn-A1, Vrn-B1, Vrn-D1 (common wheat) and Vrn-H1 (barley) alleles show no polymorphisms in the promoter region relative to their respective recessive alleles. In this study, we sequenced the complete VRN-1 gene from these accessions and found that all of them have large deletions within the first intron, which overlap in a 4-kb region. Furthermore, a 2.8-kb segment within the 4-kb region showed high sequence conservation among the different recessive alleles. PCR markers for these deletions showed that similar deletions were present in all the accessions with known Vrn-B1 and Vrn-D1 alleles, and in 51 hexaploid spring wheat accessions previously shown to have no polymorphisms in the VRN-A1 promoter region. Twenty-four tetraploid wheat accessions had a similar deletion in VRN-A1 intron 1. We hypothesize that the 2.8-kb conserved region includes regulatory elements important for the vernalization requirement. Epistatic interactions between VRN-H2 and the VRN-H1 allele with the intron 1 deletion suggest that the deleted region may include a recognition site for the flowering repression mediated by the product of the VRN-H2 gene of barley.