GrainGenes Reference Report: TPJ-38-460
Reference
TPJ-38-460
Title
Chloroplast development affects expression of phage-type RNA polymerases in barley leaves
Journal
Plant Journal
Year
2004
Volume
38
Pages
460-472
Author
Emanuel C Weihe A Graner A Hess WR Borner T
Abstract
Summary: We have identified the barley gene and cDNA encoding the plastid phage-type RNA polymerase (RNAP), nuclear-encoded plastid RNAP (RpoTp), and the nearly full-length cDNA of the mitochondrial RNAP, nuclear-encoded mitochondrial RNAP (RpoTm). RpoTp spans more than 9000 nt, consists of 19 exons and 18 introns, gives rise to a 3632-nt mRNA and is localized to the long arm of chromosome 1 (7H). The length of the deduced polypeptide is 948 residues. The mRNA levels of RpoTp and RpoTm were determined in roots and primary leaf sections of 7-day-old barley seedlings of the albostrians mutant, which were either phenotypically normal and exhibited a gradient of chloroplast development, or contained ribosome-deficient undifferentiated plastids. Transcript levels of RpoTp and RpoTm in almost all sections reached higher concentrations in plastid ribosome-deficient leaves than in the wild-type material, except in the most basal part of the leaf. These data indicate a role of plastid-to-nucleus signalling in the expression of the two RpoT genes. The mRNA levels of the plastid genes, (beta)-subunit of plastid-encoded RNAP (rpoB), proteolytic subunit of the Clp protease (clpP) and ribosomal protein Rpl2 (rpl2), all known to be transcribed by the nuclear-encoded RNAP (NEP), followed closely the pattern of RpoTp mRNA accumulation, strongly suggesting that RpoTp and NEP are identical. Transcripts of RpoTm and RpoTm-transcribed mitochondrial genes cytochrome oxidase subunit 2 (coxII) and ATPase subunit 9 (atp9) accumulated to the highest levels in the most basal parts of the leaf and declined considerably towards the leaf tip with a pronounced reduction in green versus white leaves. Our data revealed a marked influence of the developmental stage of the plastid on the expression and activity of organellar phage-type RNAPs and their target genes. Thus, interorganellar cross-talk in the regulated expression of nuclear-encoded plastid and mitochondrial RNAP genes might be a key element governing the concerted expression of genes located within plastids, mitochondria and the nucleus of the plant cell
External Databases
Pubmed: 15086795
Keyword
arabidopsis thaliana
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GrainGenes Reference Report: TPJ-38-460
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GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture. | |||