Components of chlorophyll biosynthesis in a barley albina mutant unable to synthesize ?-aminolevulinic acid by utilizing the transfer RNA for glutamic acid

Hess, Wolfgang R.; Schendel, Rudolf; R�diger, Wolfhart; Fieder, Birte; B�rner, Thomas

doi:10.1007/bf01160708

Cited by 33 publications

(8 citation statements)

References 39 publications

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“…These sections were of unequal length, 2.5 mm each for the first four sections and 10 mm for the other sections, in order to follow the rapid differentiation process in the most basal cells more precisely (Figure 4). In the case of entirely white leaves, it has been shown previously that the pigment content is approximately four orders of magnitude lower than in the green leaves (Hess et al ., 1992). All parts of white albostrians leaves harbour the same type of undifferentiated mutant plastids, i.e.…”

Section: Resultssupporting

confidence: 88%

Chloroplast development affects expression of phage‐type RNA polymerases in barley leaves

et al. 2004

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SummaryWe have identi®ed 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-de®-cient undifferentiated plastids. Transcript levels of RpoTp and RpoTm in almost all sections reached higher concentrations in plastid ribosome-de®cient 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, b-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 nuclearencoded 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 in¯uence 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.

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Section: Resultssupporting

confidence: 88%

Chloroplast development affects expression of phage‐type RNA polymerases in barley leaves

et al. 2004

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“…The nuclear barley mutant albostrians (Hagemann and Scholz, 1962) appears ideally suited to test these suppositions experimentally. More recently this ribosome deficiency was corroborated by Northern blot analysis with a probe specific for chloroplast 16S ribosomal RNA (Hess et al, 1992) as well as by Western blot analysis using an antiserum against ribosomal protein L2 . The latter, which can survive only up to an extended seedling state, again contain only undifferentiated, ribosomeless plastids in which no translation of plastome encoded mRNAs can take place (Borner and Hess, 1993).…”

Section: Resultsmentioning

confidence: 87%

Editing of the chloroplast rpoB transcript is independent of chloroplast translation and shows different patterns in barley and maize.

et al. 1993

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Sequence analysis of amplified cDNAs derived from the maize chloroplast rpoB transcript which encodes the beta subunit of a chloroplast specific, DNA dependent RNA polymerase reveals four C‐to‐U editing sites clustered within 150 nucleotides of the 5′ terminal region of the rpoB message. These newly identified editing sites confirm the bias of chloroplast editing for certain codon transitions and for second codon positions which both appear suggestive for an involvement of the translational apparatus in the editing process. This supposition prompted us to investigate editing of the rpoB transcript from ribosome deficient, and hence protein synthesis deficient, plastids of the barley mutant albostrians. In this mutant editing is, however, not impaired at any of the editing sites functional in the barley wild type rpoB transcript. This demonstrates that chloroplast editing is neither linked to nor dependent on the chloroplast translational apparatus. As a further consequence any peptide components required for chloroplast editing must be encoded in the nuclear genome. In spite of strong sequence conservation only three of the four editing sites identified in the maize rpoB transcript are functional in barley. This indicates that sequences surrounding an editing site alone are not sufficient as determinants for the editing process in chloroplasts, but that trans‐acting templates carrying the editing information for each individual site may also be required.

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“…However, it remains to be shown whether the plastid DNA in white leaves actually contains a mutation caused by a nuclear gene or whether the maternal inheritance of the phenotype is due the lack of plastid ribosomes (Börner & Sears 1986; Zubko & Day 1998). The albostrians mutant is well characterized: white seedlings contain highly rudimentary plastids which are photosynthetically inactive, have only trace amounts of chlorophylls and lack ribosomes (Hess et al . 1992; Hess et al .…”

Section: Introductionmentioning

confidence: 99%

Inter‐organellar crosstalk in higher plants: impaired chloroplast development affects mitochondrial gene and transcript levels

et al. 1999

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SummaryCo-ordination of gene expression between the three genomes present in plastids, mitochondria and nucleus is of crucial importance for plant cells. Previous studies revealed that in white leaves of the albostrians (Hordeum vulgare cv. Haisa) mutant, photosynthesisrelated plastid and nuclear genes are expressed only at an extremely low level. The plastids of this mutant lack ribosomes, photosynthetic activity and have only rudimentary membrane systems. Here we report on the expression of mitochondrial genes in albostrians barley. Steady-state RNA levels of the mitochondrial genes encoding cytochrome oxidase or ATPase subunits, coxII, coxIII, atpA, atp6, atp9 and cob, were observed to be consistently elevated in the white leaves but not in roots. Investigation of mitochondrial DNA revealed an about three-fold enhanced mitochondrial gene copy number in white compared to green leaf cells, but no differential ampli®cation of mitochondrial genes. Analysis of plants in which the white albostrians plastids were combined with a new nuclear background showed that the enhanced transcript levels were a consequence of the impaired plastids and not of the nuclear albostrians allele. Furthermore, plants bleached by the carotenoid biosynthesis inhibitor nor¯urazon also showed an enhanced mitochondrial transcript level. These ®ndings allow the conclusion that lack of chloroplast activity in an otherwise fully differentiated leaf leads to an increase in mitochondrial gene copy number and an elevated level of mitochondrial transcripts. Our results indicate an in¯uence of plastids on the genetic apparatus of mitochondria in leaves but not in roots.

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Components of chlorophyll biosynthesis in a barley albina mutant unable to synthesize ?-aminolevulinic acid by utilizing the transfer RNA for glutamic acid

Cited by 33 publications

References 39 publications

Chloroplast development affects expression of phage‐type RNA polymerases in barley leaves

Chloroplast development affects expression of phage‐type RNA polymerases in barley leaves

Editing of the chloroplast rpoB transcript is independent of chloroplast translation and shows different patterns in barley and maize.

Inter‐organellar crosstalk in higher plants: impaired chloroplast development affects mitochondrial gene and transcript levels

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