Department of Genetics and Plant Production, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas Zaragoza, Spain.
Department of Genetics and Plant Production, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas Zaragoza, Spain ; Fundación ARAID Zaragoza, Spain.
Front Plant Sci. 2014 Jun 6;5:251. doi: 10.3389/fpls.2014.00251. eCollection 2014.
Flowering time in plants is a tightly regulated process. In barley (Hordeum vulgare L.), HvFT1, ortholog of FLOWERING LOCUS T, is the main integrator of the photoperiod and vernalization signals leading to the transition from vegetative to reproductive state of the plant. This gene presents sequence polymorphisms affecting flowering time in the first intron and in the promoter. Recently, copy number variation (CNV) has been described for this gene. An allele with more than one copy was linked to higher gene expression, earlier flowering, and an overriding effect of the vernalization mechanism. This study aims at (1) surveying the distribution of HvFT1 polymorphisms across barley germplasm and (2) assessing gene expression and phenotypic effects of HvFT1 alleles. We analyzed HvFT1 CNV in 109 winter, spring, and facultative barley lines. There was more than one copy of the gene (2-5) only in spring or facultative barleys without a functional vernalization VrnH2 allele. CNV was investigated in several regions inside and around HvFT1. Two models of the gene were found: one with the same number of promoters and transcribed regions, and another with one promoter and variable number of transcribed regions. This last model was found in Nordic barleys only. Analysis of HvFT1 expression showed that association between known polymorphisms at the HvFT1 locus and the expression of the gene was highly dependent on the genetic background. Under long day conditions the earliest flowering lines carried a sensitive PpdH1 allele. Among spring cultivars with different number of copies, no clear relation was found between CNV, gene expression and flowering time. This was confirmed in a set of doubled haploid lines of a population segregating for HvFT1 CNV. Earlier flowering in the presence of several copies of HvFT1 was only seen in cultivar Tammi, which carries one promoter, suggesting a relation of gene structure with its regulation. HvCEN also affected to a large extent flowering time.
植物的开花时间是一个受到严格调控的过程。在大麦（Hordeum vulgare L.）中，HvFT1 是光周期和春化信号的主要整合因子，导致植物从营养生长状态向生殖生长状态的转变。该基因在第一内含子和启动子中存在影响开花时间的序列多态性。最近，该基因的拷贝数变异（CNV）已被描述。一个具有多个拷贝的等位基因与更高的基因表达、更早的开花以及春化机制的主导作用有关。本研究旨在：（1）调查 HvFT1 多态性在大麦种质资源中的分布；（2）评估 HvFT1 等位基因的基因表达和表型效应。我们分析了 109 个冬、春和兼性大麦品系中的 HvFT1 CNV。只有在春性或兼性大麦中，没有功能正常的春化 VrnH2 等位基因，才存在该基因的多个拷贝（2-5 个）。在 HvFT1 内部和周围的几个区域进行了 CNV 研究。发现了两种基因模型：一种具有相同数量的启动子和转录区域，另一种具有一个启动子和可变数量的转录区域。后一种模型仅在北欧大麦中发现。HvFT1 表达分析表明，HvFT1 基因座上已知多态性与基因表达之间的关联高度依赖于遗传背景。在长日照条件下，开花最早的品系携带敏感的 PpdH1 等位基因。在具有不同拷贝数的春性品种中，CNV、基因表达和开花时间之间没有明显的关系。在一个 HvFT1 CNV 分离的群体的双倍单倍体品系中得到了证实。只有在携带一个启动子的 Tammi 品种中，HvFT1 多个拷贝的存在才导致开花时间提前，这表明基因结构与其调控之间存在关系。HvCEN 也在很大程度上影响了开花时间。
