title: Building up of the plastid transcriptional machinery during germination and early plant development.
abstract: 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.
authors.affiliation: Laboratoire Plastes et Differenciation Cellulaire, Université Joseph Fourier and Centre National de la Recherche Scientifique, F-38041 Grenoble, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Demarsy
authors.forename: Florence
authors.initials: F
authors.lastname: Courtois
authors.forename: Jacinthe
authors.initials: J
authors.lastname: Azevedo
authors.forename: Laurence
authors.initials: L
authors.lastname: Buhot
authors.forename: Silva
authors.initials: S
authors.lastname: Lerbs-Mache
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018525:Germination / Q000502:physiology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D018724:Spinacia oleracea / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant