Demarsy Emilie, Courtois Florence, Azevedo Jacinthe, Buhot Laurence, Lerbs-Mache Silva
Laboratoire Plastes et Differenciation Cellulaire, Université Joseph Fourier and Centre National de la Recherche Scientifique, F-38041 Grenoble, France.
Plant Physiol. 2006 Nov;142(3):993-1003. doi: 10.1104/pp.106.085043. Epub 2006 Sep 8.
The plastid genome is transcribed by three different RNA polymerases, one is called plastid-encoded RNA polymerase (PEP) and two are called nucleus-encoded RNA polymerases (NEPs). PEP transcribes preferentially photosynthesis-related genes in mature chloroplasts while NEP transcribes preferentially housekeeping genes during early phases of plant development, and it was generally thought that during plastid differentiation the building up of the NEP transcription system precedes the building up of the PEP transcription system. We have now analyzed in detail the establishment of the two different transcription systems, NEP and PEP, during germination and early seedling development on the mRNA and protein level. Experiments have been performed with two different plant species, Arabidopsis (Arabidopsis thaliana) and spinach (Spinacia oleracea). Results show that the building up of the two different transcription systems is different in the two species. However, in both species NEP as well as PEP are already present in seeds, and results using Tagetin as a specific inhibitor of PEP activity demonstrate that PEP is important for efficient germination, i.e. PEP is already active in not yet photosynthetically active seed plastids.
质体基因组由三种不同的RNA聚合酶转录，一种称为质体编码的RNA聚合酶（PEP），另外两种称为核编码的RNA聚合酶（NEP）。PEP优先转录成熟叶绿体中与光合作用相关的基因，而NEP在植物发育早期优先转录管家基因，并且一般认为在质体分化过程中，NEP转录系统的建立先于PEP转录系统的建立。我们现在已经在mRNA和蛋白质水平上详细分析了在萌发和幼苗早期发育过程中两种不同转录系统NEP和PEP的建立情况。我们用两种不同的植物物种拟南芥（Arabidopsis thaliana）和菠菜（Spinacia oleracea）进行了实验。结果表明，这两种不同转录系统的建立在这两个物种中有所不同。然而，在这两个物种的种子中都已经存在NEP和PEP，并且使用Tagetin作为PEP活性的特异性抑制剂的结果表明，PEP对有效萌发很重要，即PEP在尚未进行光合作用的种子质体中已经具有活性。
