The rbcL genes of two Cuscuta species, C-gronovii and C-subinclusa, are transcribed by the nuclear-encoded plastid RNA polymerase (NEP)
The rbcL genes of two Cuscuta species, C-gronovii and C-subinclusa, are transcribed by the nuclear-encoded plastid RNA polymerase (NEP)
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DOI：
10.1007/s00425-004-1260-3
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发表时间：
2004-07-01
期刊：
影响因子：
4.3
通讯作者：
Krupinska, K
中科院分区：
文献类型：
--
作者：
Berg, S;Krause, K;Krupinska, K
全寄生有花植物菟丝子属（Cuscuta）的一些种类，如菟丝子C. reflexa等植物保留了编码光合作用相关基因产物的质体基因组以及质体编码的RNA聚合酶（PEP）。与此相反，其他物种，如C. gronovii和C.亚基的rpo基因丢失，而光合作用基因保留。为了确保光合作用相关基因的表达，在PEP的情况下，需要质体基因组内的一些适应，使基因转录完全由核编码的质体RNA聚合酶（NEP）介导。在这项研究中，我们分析了启动子序列的保守性和转录起始位点的一个典型的PEP基因的非寄生植物，rbcL，编码大亚基的核酮糖二磷酸羧化酶/加氧酶。我们发现，尽管rbcL的编码区在不同的菟丝子属物种和烟草中具有高度的序列保守性，但Cuscuta的5'端非编码区在不同的物种和烟草中具有高度的序列保守性。gronovii和C. subinclusa遭受了广泛的缺失，包括存在于C.反射和烟草。引物延伸分析使得能够鉴定C. gronovii和C. subinclusa中的5'非编码区中检测不到的。反射
Some species of the holoparasitic flowering plant genus Cuscuta, like C. reflexa, have retained a plastid genome that encodes photosynthesis-related gene products as well as the plastid-encoded RNA polymerase (PEP). In contrast, other species like C. gronovii and C. subinclusa have lost the rpo genes coding for the PEP subunits while photosynthetic genes have been retained. In order to ensure expression of the photosynthesis-related genes in the absence of PEP, a number of adaptations within the plastid genome were required that enable gene transcription mediated exclusively by the nuclear-encoded plastid RNA polymerase (NEP). In this study we analyzed promoter sequence conservation and transcription start sites of a typical PEP gene of non-parasitic plants, rbcL, which codes for the large subunit of ribulose bisphosphate carboxylase/oxygenase. We show that despite high sequence conservation of the coding region of rbcL among different Cuscuta species and tobacco, the 5' non-coding regions of C. gronovii and C. subinclusa have suffered extensive deletions encompassing the PEP promoter that is present in C. reflexa and tobacco. Primer-extension analyses enabled the identification of transcripts initiated at NEP promoter motifs in C. gronovii and C. subinclusa that are not detectable in the 5' non-coding region of C. reflexa.