A genetic network of flowering-time genes in wheat leaves, in which an APETALA1/FRUITFULL-like gene, VRN1, is upstream of FLOWERING LOCUS T.
A genetic network of flowering-time genes in wheat leaves, in which an APETALA1/FRUITFULL-like gene, VRN1, is upstream of FLOWERING LOCUS T.
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DOI：
10.1111/j.1365-313x.2009.03806.x
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
Murai K
中科院分区：
文献类型：
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作者：
Shimada S;Ogawa T;Kitagawa S;Suzuki T;Ikari C;Shitsukawa N;Abe T;Kawahigashi H;Kikuchi R;Handa H;Murai K
为了阐明小麦开花的遗传机制，我们对开花时间基因进行了表达、突变和转基因研究。日表达分析表明，在长日（LD）和短日（SD）条件下，小麦aptala1 /FRUITFULL同源物开花激活因子VRN1在叶片中均以节律性方式表达。在低光照条件下，VRN1在光照期的表达上调伴随着开花位点T（开花位点T）转录本的积累。此外，在小麦（Triticum monococum）的维持营养期（mvp）突变体中不表达FT，该突变体具有VRN1的零等位基因，并且从未从营养期过渡到生殖期。这些结果表明，VRN1位于FT的上游，并在LD条件下上调FT的表达。在转基因面包小麦（Triticum aestivum）中，FT的过表达导致VRN1上调和VRN2下调，VRN1被认为是VRN1的抑制基因。这些结果表明，在转基因植株中，FT抑制VRN2的表达，导致VRN1的表达增加。基于这些结果，我们提出了一个小麦叶片开花时间基因遗传网络模型，其中VRN1位于FT的上游，并通过VRN2形成一个正反馈回路。mvp突变体具有VRN2和VRN1的空等位基因，因为它是从缺乏VRN2的春小麦品系中获得的。在mvp突变体中不表达FT的事实支持了目前的模型。
To elucidate the genetic mechanism of flowering in wheat, we performed expression, mutant and transgenic studies of flowering-time genes. A diurnal expression analysis revealed that a flowering activator VRN1, an APETALA1/FRUITFULL homolog in wheat, was expressed in a rhythmic manner in leaves under both long-day (LD) and short-day (SD) conditions. Under LD conditions, the upregulation of VRN1 during the light period was followed by the accumulation of FLOWERING LOCUS T (FT) transcripts. Furthermore, FT was not expressed in a maintained vegetative phase (mvp) mutant of einkorn wheat (Triticum monococcum), which has null alleles of VRN1, and never transits from the vegetative to the reproductive phase. These results suggest that VRN1 is upstream of FT and upregulates the FT expression under LD conditions. The overexpression of FT in a transgenic bread wheat (Triticum aestivum) caused extremely early heading with the upregulation of VRN1 and the downregulation of VRN2, a putative repressor gene of VRN1. These results suggest that in the transgenic plant, FT suppresses VRN2 expression, leading to an increase in VRN1 expression. Based on these results, we present a model for a genetic network of flowering-time genes in wheat leaves, in which VRN1 is upstream of FT with a positive feedback loop through VRN2. The mvp mutant has a null allele of VRN2, as well as of VRN1, because it was obtained from a spring einkorn wheat strain lacking VRN2. The fact that FT is not expressed in the mvp mutant supports the present model.