Showing papers by "Pal Maliga published in 1997"

The two RNA polymerases encoded by the nuclear and the plastid compartments transcribe distinct groups of genes in tobacco plastids

Abstract: The plastid genome in photosynthetic higher plants encodes subunits of an Escherichia coli-like RNA polymerase (PEP) which initiates transcription from E.coli sigma70-type promoters. We have previously established the existence of a second nuclear-encoded plastid RNA polymerase (NEP) in photosynthetic higher plants. We report here that many plastid genes and operons have at least one promoter each for PEP and NEP (Class II transcription unit). However, a subset of plastid genes, including photosystem I and II genes, are transcribed from PEP promoters only (Class I genes), while in some instances (e.g. accD) genes are transcribed exclusively by NEP (Class III genes). Sequence alignment identified a 10 nucleotide NEP promoter consensus around the transcription initiation site. Distinct NEP and PEP promoters reported here provide a general mechanism for group-specific gene expression through recognition by the two RNA polymerases.

Plastid transformation in arabidopsis thaliana

Abstract: This invention provides methods and compositions for obtaining transplastomic Arabidopsis and Brassica plants. Specifically, the method provides culturing protocols and compositions that facilitate the regeneration of transformed plants following delivery of exogenous, beneficial DNA molecules.

A negative selection scheme based on the expression of cytosine deaminase in plastids.

Abstract: The enzyme cytosine deaminase (CD) encoded by codA catalyzes deamination of cytosine to uracil. CD is present in prokaryotes and in many eukaryotic micro-organisms, but is absent in higher plants. 5-fluorocytosine (5FC) is metabolized in CD-expressing cells, causing cellular death. A chimeric codA has been introduced into the tobacco plastid genome and 5FC was used to select against tissue culture cells and seedlings expressing CD. This negative selection scheme will be useful in identifying nuclear genes which control plastid gene expression in higher plants.

Targeted deletion of sprA from the tobacco plastid genome indicates that the encoded small RNA is not essential for pre-16S rRNA maturation in plastids.

Abstract: The small plastid RNA (spRNA) which includes a segment that is complementary to the pre-16S rRNA has been suggested to facilitate maturation of pre-16S rRNA in tobacco. To investigate the function of spRNA, the gene encoding it (sprA) was removed from the plastid genome using targeted gene deletion. We report here that deletion of sprA does not significantly affect pre-16S rRNA maturation, nor does it cause any obvious phenotype. Although the spRNA still may be involved in rRNA maturation, it is non-essential under normal growth conditions.

Editing-based selectable plastid marker genes

Abstract: Disclosed are novel DNA constructs for selecting plastid transformants in higher plants. Also disclosed are editing based selectable marker genes which require editing at the transcriptional level for expression of the selectable marker gene. Vectors including such edited upstream sequences operably linked to slectable marker genes facilitate the isolation of plastid, rather than nuclear transformants in higher plants.

Transformations des plastides chez arabidopsis thaliana

Abstract: L'invention concerne des methodes et des compositions permettant d'obtenir des plants d'Arabidopsis et de Brassica transplastomiques. Specifiquement, la methode permet d'obtenir des protocoles de culture et des compositions qui facilitent la regeneration de plants transformes apres administration de molecules d'ADN exogenes benefiques.