Himi Eiko, Noda Kazuhiko
Research Institute of Bioresources, Okayama University, Chuo 2-20-1, Kurashiki, Okayama, 710-0046, Japan.
J Exp Bot. 2004 Feb;55(396):365-75. doi: 10.1093/jxb/erh046. Epub 2004 Jan 12.
DFR is involved in an important step in the flavonoid biosynthesis pathway upstream of anthocyanin, proanthocyanidin, and phlobaphene production, which contributes to the pigmentation of various plant tissues. Full genomic sequences of three DFRs were isolated in hexaploid wheat. Loci of TaDFRs were found in a more proximal region of the long arm of chromosomes of homoeologous group 3 than the R gene for red grain colour of wheat. These DFRs were designated TaDFR-A, TaDFR-B, and TaDFR-D on chromosome 3A, 3B, and 3D, respectively. In the 5' upstream region of DFR genes, two or three combinations of a G box core element and a putative binding site for a Myb-type transcription factor, P, of maize were found. Expression of DFR reached a maximal level in red grain of wheat cv. Chinese Spring (CS) at 5 d post-anthesis (DPA) and decreased gradually in the grain coat tissue from 10 to 20 DPA, in contrast to a very low expression level of DFR in white wheat grain during the same period. These DFRs differed in their expression. TaDFR-B and -D were expressed predominantly in grains. In developing leaves, DFR expression was light-responsive, and TaDFR-B was more up-regulated in leaves and roots than the other two.
二氢黄酮醇4-还原酶（DFR）参与花青素、原花青素和花白素合成上游的类黄酮生物合成途径中的一个重要步骤，这有助于各种植物组织的色素沉着。在六倍体小麦中分离出了三个DFR的全基因组序列。与小麦红色籽粒颜色的R基因相比，TaDFR的基因座位于同源群3染色体长臂的更近端区域。这些DFR分别在3A、3B和3D染色体上被命名为TaDFR-A、TaDFR-B和TaDFR-D。在DFR基因的5'上游区域，发现了G盒核心元件与玉米Myb型转录因子P的假定结合位点的两种或三种组合。DFR的表达在小麦品种中国春（CS）的红色籽粒中于花后5天（DPA）达到最高水平，并在种皮组织中从10 DPA到20 DPA逐渐下降，而同期白色小麦籽粒中DFR的表达水平非常低。这些DFR的表达有所不同。TaDFR-B和-D主要在籽粒中表达。在发育中的叶片中，DFR的表达对光有响应，并且TaDFR-B在叶片和根中的上调程度比其他两个更高。
