Carotenoid biosynthesis during tomato fruit development:: regulatory role of 1-deoxy-D-xylulose 5-phosphate synthase
Carotenoid biosynthesis during tomato fruit development:: regulatory role of 1-deoxy-D-xylulose 5-phosphate synthase
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DOI：
10.1046/j.1365-313x.2000.00764.x
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发表时间：
2000-06-01
期刊：
影响因子：
7.2
通讯作者：
Boronat, A
中科院分区：
文献类型：
--
作者：
Lois, LM;Rodríguez-Concepción, M;Boronat, A
植物类异戊二烯是一类非均相的化合物，不仅在植物的生长发育中发挥重要作用，而且在植物与环境的相互作用中也发挥着重要作用。高等植物有两条合成异戊二烯的途径：位于胞浆/内质网的甲戊酸途径和最近发现的存在于质体内的甲戊酸非依赖性途径(Rohmer途径)。为了研究Rohmer途径在调节类异戊二烯合成中的作用，我们克隆了该途径的第一个酶--1-脱氧-D-木糖-5-磷酸合成酶(DXS)。我们展示了植物DXS的体内活性和叶绿体靶向性。番茄DXS基因的表达分析表明，在果实发育过程中，mRNA的积累受到发育和器官特异性的调控，并且与类胡萝卜素的合成密切相关。1-脱氧-D-木糖饲喂实验，以及DXS和PSY1(编码果实特异性植烯合酶亚型)在野生型和黄肉突变果实中的表达分析表明，DXS在果实成熟早期催化了潜在的类胡萝卜素生物合成的第一步。我们的结果改变了目前认为PSY1是番茄果实胡萝卜素合成的唯一调节酶的观点，并表明DXS和PSY1在控制果实类胡萝卜素合成方面具有协同作用。
Plant isoprenoids represent a heterogeneous group of compounds which play essential roles not only in growth and development, but also in the interaction of plants with their environment. Higher plants contain two pathways for the biosynthesis of isoprenoids: the mevalonate pathway, located in the cytosol/endoplasmic reticulum, and the recently discovered mevalonate-independent pathway (Rohmer pathway), located in the plastids. In order to evaluate the function of the Rohmer pathway in the regulation of the synthesis of plastidial isoprenoids, we have isolated a tomato cDNA encoding 1-deoxy-D-xylulose 5-phosphate synthase (DXS), the first enzyme of the pathway. We demonstrate in vivo activity and plastid targeting of plant DXS. Expression analysis of the tomato DXS gene indicates developmental and organ-specific regulation of mRNA accumulation and a strong correlation with carotenoid synthesis during fruit development. 1-Deoxy-D-xylulose feeding experiments, together with expression analysis of DXS and PSY1 (encoding the fruit-specific isoform of phytoene synthase) in wild-type and yellow flesh mutant fruits, indicate that DXS catalyses the first potentially regulatory step in carotenoid biosynthesis during early fruit ripening. Our results change the current view that PSY1 is the only regulatory enzyme in tomato fruit carotenogenesis, and point towards a coordinated role of both DXS and PSY1 in the control of fruit carotenoid synthesis.