A bHLH transcription factor mediates organ, region and flower type specific signals on dihydroflavonol-4-reductase (dfr) gene expression in the inflorescence of Gerbera hybrida (Asteraceae)
A bHLH transcription factor mediates organ, region and flower type specific signals on dihydroflavonol-4-reductase (dfr) gene expression in the inflorescence of Gerbera hybrida (Asteraceae)
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DOI：
10.1046/j.1365-313x.1998.00273.x
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发表时间：
1998-10-01
期刊：
影响因子：
7.2
通讯作者：
Teeri, TH
中科院分区：
文献类型：
--
作者：
Elomaa, P;Mehto, M;Teeri, TH
被子植物菊科的特点是复合花序，这是由不同类型的花组成的高度有组织的结构。为了从分子水平上探讨菊科植物花器官分化的调控机制，本研究对非洲菊类黄酮生物合成的调控进行了研究。二氢黄酮醇-4-还原酶（dfr）的表达在所有非洲菊品种的几个解剖学水平上都受到花色素苷着色模式的调控。我们已经分离了一个启动子的dfr基因之一，Pgdfr 2。Pgdfr 2-uidA构建体转基因的非洲菊植物揭示了来自一个品种的Pgdfr 2启动子的活性遵循具有不同颜色模式的其他品种中的色素沉着。因此，很明显，所观察到的复杂的调节DIR的表达发生在反式。为了确定的反式作用的监管机构，我们分离的cDNA（gmyc 1）同源的先前表征的基因编码的bHLH型调控植物中的花青素途径。gmyc 1在不同品种中的表达表明，gmyc 1主要调节花冠和心皮中的dfr活性，而在冠毛和雄蕊中不起作用。特别是在非洲菊，相同的模式gmyc 1和dir在花冠组织中的表达表明，GMYC 1也调节dir表达的区域和花型特异性的方式。我们的研究表明，在非洲菊GMYC 1-dfr的相互作用是几个发育过程的一部分，远菊科（如规格的花类型在整个复合花序），而在其他过程（如分化的萼片冠毛）其他监管机构控制dfr的表达，以确定空间特异性。
The angiosperm family Asteraceae is characterized by composite inflorescences, which are highly organized structures consisting of different types of flowers. In order to approach the control of floral organ differentiation in Asteraceae at molecular level, we are studying regulation of flavonoid biosynthesis in Gerbera hybrida. Dihydroflavonol-4-reductase (dfr) expression is regulated according to anthocyanin pigmentation patterns in ail tested gerbera varieties at several anatomical levels. We have isolated a promoter for one of the dfr genes, Pgdfr2. Gerbera plants transgenic for a Pgdfr2-uidA construct reveal that the activity of the Pgdfr2 promoter from one variety follows the pigmentation in other varieties which have different color patterns. It is thus evident that the observed complex regulation of dir expression occurs in trans. In order to identify the trans-acting regulators, we isolated a cDNA (gmyc1) homologous to the previously characterized genes encoding bHLH-type regulators of the anthocyanin pathway in plants. the expression of gmyc1 in different varieties suggests that it has a major role in regulating dfr activity in corolla and carpel, but not in pappus and stamen. Specifically in gerbera, the identical patterns of gmyc1 and dir expression in corolla tissue suggest that GMYC1 also regulates dir expression in a region and flower type specific manner. Our studies show that in gerbera GMYC1-dfr interaction is part of several developmental processes characteristic far Asteraceae (such as specification of flower types across the composite inflorescence), whereas in other processes (such as differentiation of sepal as pappus) other regulators control dfr expression to determine the spatial specificity.