Gollop Rachel, Even Sylvie, Colova-Tsolova Violeta, Perl Avihai
Department of Fruit Tree Breeding and Molecular Genetics, ARO, The Volcani Center, PO Box 6, Bet-Dagan 50250, Israel.
J Exp Bot. 2002 Jun;53(373):1397-409.
Dihydroflavonol reductase (DFR) is a key enzyme involved in anthocyanin biosynthesis and proanthocyanidin synthesis in grape. DFR catalyses the reduction of dihydroflavonols to leucoanthocyanidins in the anthocyanin pathway. The DFR products, the leucoanthocyanidins, are substrates for the next step in the anthocyanin pathway and are also the substrates for the proanthocyanidin pathway. In the present study the promoter of the grape dfr gene was cloned. Analysis of the dfr promoter sequence revealed the existence of several putative DNA binding motifs. The dfr promoter was fused to the uidA gene and the control of this fusion and the endogenous dfr gene expression, was studied in transformed plants and in red cell suspension originated from fruits. The dfr promoter-uidA gene fusion was expressed in leaves, roots and stems. Deletions of the dfr promoter influenced the specificity of the expression of the GUS gene fusion in plantlet roots and the level of expression in plants and in the red cell suspension originated from fruits. The deletion analysis of the dfr promoter suggests that a specific sequence located between -725 to -233 might be involved in expression of the dfr gene in fruits. Light, calcium and sucrose induced the dfr gene expression. In the transformed suspension cultures, expression of both the endogenous dfr gene and the dfr promoter-uidA gene fusions was induced by white light. The induction by both light and calcium suggests the possible involvement of a UV receptors signal transduction pathway in the induction of the dfr gene. The induction of the dfr gene and the dfr promoter-uidA gene fusions by light and sucrose indicates a close interaction between sucrose and light signalling pathways.
二氢黄酮醇还原酶（DFR）是葡萄中参与花青素生物合成和原花青素合成的关键酶。DFR催化花青素途径中二氢黄酮醇还原为无色花青素。DFR的产物无色花青素是花青素途径下一步的底物，也是原花青素途径的底物。在本研究中，克隆了葡萄dfr基因的启动子。对dfr启动子序列的分析揭示了几个假定的DNA结合基序的存在。将dfr启动子与uidA基因融合，并在转化植株和果实来源的红色细胞悬浮液中研究这种融合以及内源性dfr基因表达的调控。dfr启动子-uidA基因融合在叶、根和茎中表达。dfr启动子的缺失影响了GUS基因融合在幼苗根中的表达特异性以及在植株和果实来源的红色细胞悬浮液中的表达水平。dfr启动子的缺失分析表明，位于-725至-233之间的特定序列可能参与dfr基因在果实中的表达。光、钙和蔗糖诱导dfr基因表达。在转化的悬浮培养物中，白光诱导内源性dfr基因和dfr启动子-uidA基因融合的表达。光和钙的诱导表明紫外线受体信号转导途径可能参与dfr基因的诱导。光和蔗糖对dfr基因和dfr启动子-uidA基因融合的诱导表明蔗糖和光信号途径之间存在密切相互作用。
