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Biomedical subjects

G P Redei

Publications and source records attributed to G P Redei.

5 recordsLinked to original sources
PubMed1991

T-DNA integration: a mode of illegitimate recombination in plants.

Transferred DNA (T-DNA) insertions of Agrobacterium gene fusion vectors and corresponding insertional target sites were isolated from transgenic and wild type Arabidopsis thaliana plants. Nucleotide sequence comparison of wild type and T-DNA-tagged genomic loci showed that T-DNA integration resulted in target site deletions of 29-73 bp. In those cases where integrated T-DNA segments turned out to be smaller than canonical ones, the break-points of target deletions and T-DNA insertions overlapped and consisted of 5-7 identical nucleotides. Formation of precise junctions at the right T-DNA border, and DNA sequence homology between the left termini of T-DNA segments and break-points of target deletions were observed in those cases where full-length canonical T-DNA inserts were very precisely replacing plant target DNA sequences. Aberrant junctions were observed in those transformants where termini of T-DNA segments showed no homology to break-points of target sequence deletions. Homology between short segments within target sites and T-DNA, as well as conversion and duplication of DNA sequences at junctions, suggests that T-DNA integration results from illegitimate recombination. The data suggest that while the left T-DNA terminus and both target termini participate in partial pairing and DNA repair, the right T-DNA terminus plays an essential role in the recognition of the target and in the formation of a primary synapsis during integration.

Base Sequence↗
PubMed1990

Isolation of a gene encoding a novel chloroplast protein by T-DNA tagging in Arabidopsis thaliana.

A recessive pale mutation, designated as cs, was identified by transferred-DNA (T-DNA)-mediated insertional mutagenesis in Arabidopsis thaliana. The pale mutation, cosegregating with the hygromycin resistance marker of the T-DNA, was mapped to the position of the ch-42 (chlorata) locus on chromosome 4. Lack of genetic complementation between cs and ch-42 mutants indicated allelism. Plant boundaries of the T-DNA insert rescued from the pale mutant were used as probes for the isolation of genomic and full-length cDNA clones of the wild-type cs gene. Transformation of the pale mutant with T-DNA vectors carrying these clones resulted in a normal green phenotype, thus demonstrating positive complementation of the T-DNA induced mutation. DNA sequence comparison of the cs mutant and its wild-type allele revealed that the T-DNA insertion occurred 11 bp upstream of the stop codon. A fusion protein, seven amino acids longer than its wild-type counterpart of Mr 46,251, is therefore synthesized in the pale mutant. Transcript analysis during dark-light transition, in vitro protein transport assay, and the absence of DNA sequence homology between cs and known genes indicates that the light regulated expression of the cs gene results in the synthesis of a novel chloroplast protein.

Alleles↗
PubMed1989

High-frequency T-DNA-mediated gene tagging in plants.

An insertion element [transferred DNA (T-DNA)], transferred by soil agrobacteria into the nuclear genome of plants, was used for induction of gene fusions in Arabidopsis thaliana, Nicotiana tabacum, and Nicotiana plumbaginifolia. A promoterless aph(3')II (aminoglycoside phosphotransferase II) reporter gene was linked to the right end of the T-DNA and transformed into plants along with a plasmid replicon and a selectable hygromycin-resistance gene. Transcriptional and translational reporter gene fusions were identified by screening for APH(3')II enzyme activity in diverse tissues of transgenic plants. The frequency of gene fusions, estimated by determination of the copy number of T-DNA insertions, showed that on average 30% of T-DNA inserts induced gene fusions in Arabidopsis and Nicotiana. Gene fusions were rescued from plants by transformation of the T-DNA-linked plasmid and flanking plant DNA into Escherichia coli. By dissection of gene fusions and construction of chimeric genes, callus- and root-specific promoters were identified that showed an altered tissue specificity in the presence of a 3'-downstream-located 35S promoter. Transcript mapping of a gene fusion and expression of a non-frame transcriptional fusion of bacterial luciferase luxA and luxB genes demonstrated that dicistronic transcripts are translated in tobacco.

Base Sequence↗
PubMed1969

Gene locus specificity of the glucose effect in the thiamine pathway of the angiosperm, Arabidopsis.

All mutants at 3 loci in Arabidopsis thaliana (L.) Heynh., a higher plant, that are associated with the synthesis or coupling of the thiazole moiety of thiamine are susceptible to reversible glucose inhibition. In contrast, several different alleles involved in the synthesis of the pyrimidine moiety of the vitamin are insensitive to glucose. Glucose and maltose are equally effective inhibitors while fructose, lactose, ribose, and xylose are toxic. This toxicity is not released by added thiamine.

Journal Article↗