Plant Transposable Elements

Kunze, Reinhard; Saedler, Heinz; Lönnig, Wolf-Ekkehard

doi:10.1016/s0065-2296(08)60284-0

Cited by 128 publications

(149 citation statements)

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“…These transposons generate a 3-bp target site duplication upon insertion and produce footprints that consist of remains of the target site duplication (р3 bp), often separated by small inversions of the target site duplication without missing nucleotides at the symmetry axis (cf. Coen et al, 1986;Kunze et al, 1997). Figure 7B shows that the Ϫ1-and ϩ4-bp frameshift an2 Ϫ alleles are fully consistent with the insertion and excision of a CACTA transposon.…”

Section: The Role Of Transposons In the Generation Of An2 ϫ Allelesmentioning

confidence: 60%

“…After excision, a footprint is left behind that consists of remains of the target site duplication (у7 bp of each target site duplication; cf. Coen et al, 1986;Kunze et al, 1997) often separated by one or more inverted nucleotides of the target site duplication. Figure 7A shows that the Ϫ1-and ϩ4-bp frameshift mutations can be explained, consistent with existing models for footprint formation, by two independent excisions of the same Activator-like transposon.…”

Section: The Role Of Transposons In the Generation Of An2 ϫ Allelesmentioning

confidence: 99%

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Molecular Analysis of the anthocyanin2 Gene of Petunia and Its Role in the Evolution of Flower Color

et al. 1999

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The shape and color of flowers are important for plant reproduction because they attract pollinators such as insects and birds. Therefore, it is thought that alterations in these traits may result in the attraction of different pollinators, genetic isolation, and ultimately, (sympatric) speciation. Petunia integrifolia and P. axillaris bear flowers with different shapes and colors that appear to be visited by different insects. The anthocyanin2 ( an2 ) locus, a regulator of the anthocyanin biosynthetic pathway, is the main determinant of color differences. Here, we report an analysis of molecular events at the an2 locus that occur during Petunia spp evolution. We isolated an2 by transposon tagging and found that it encodes a MYB domain protein, indicating that it is a transcription factor. Analysis of P. axillaris subspecies with white flowers showed that they contain an2 Ϫ alleles with two alternative frameshifts at one site, apparently caused by the insertion and subsequent excision of a transposon. A third an2 ؊ allele has a nonsense mutation elsewhere, indicating that it arose independently. The distribution of polymorphisms in an2 ؊ alleles suggests that the loss of an2 function and the consequent changes in floral color were not the primary cause for genetic separation of P. integrifolia and P. axillaris. Rather, they were events that occurred late in the speciation process, possibly to reinforce genetic isolation and complete speciation. INTRODUCTIONFlowers are the structures containing the male and female sex organs of angiosperms. Flowers of diverse species display a wide range of different morphologies and pollination strategies. For instance, flowers of wind-pollinated species usually possess small and inconspicuous petals or no petals at all, whereas flowers of insect-pollinated plants usually possess large, brightly colored, and patterned petals that serve as visual signals and a landing site for visiting insects.Recent experiments suggest that the wide variety of plant and flower morphologies may have depended on the evolution of a relatively small number of genes. First, mutations at single loci, usually isolated by breeders or researchers, are sufficient to cause fundamental alterations in inflorescence architecture (Doebley et al., 1997;Souer et al., 1998). Similarly, the different shapes, colors, and color patterns of naturally occurring Mimulus (monkeyflower) spp are due to alterations at only a few (major) loci (Bradshaw et al., 1995).Second, even very different inflorescence and flower architectures appear to be determined by genes that often encode conserved proteins but that differ in their expression patterns (reviewed in Doebley and Lukens, 1998).The isolation of key regulatory loci and analysis of the molecular alterations that have taken place in them will provide new insights into the evolution and diversification of flower morphology. The biosynthesis of anthocyanin flower pigments is particularly suited for such studies, because it is a well-defined biochemical pathway that is being...

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Section: The Role Of Transposons In the Generation Of An2 ϫ Allelesmentioning

confidence: 60%

Section: The Role Of Transposons In the Generation Of An2 ϫ Allelesmentioning

confidence: 99%

Molecular Analysis of the anthocyanin2 Gene of Petunia and Its Role in the Evolution of Flower Color

et al. 1999

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“…Interestingly, the number of cells in a mature tobacco leaf (33) is at least 10 times higher than the average number of leaf cells required to select one chloroplast gene transfer event, which indicates that cells within a single leaf are not genetically identical but may differ in their nuclear genome with respect to the pattern of chloroplast DNA integrations. In addition, similar to movement of transposable elements (34,35), high-frequency insertion of chloroplast DNA into the nuclear genome may be responsible for somatic mutations by integrating into functional nuclear genes.…”

Section: Frequency Of Gene Transfermentioning

confidence: 99%

High-frequency gene transfer from the chloroplast genome to the nucleus

Stegemann

Hartmann²,

Ruf³

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

275

237

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Eukaryotic cells arose through endosymbiotic uptake of free-living bacteria followed by massive gene transfer from the genome of the endosymbiont to the host nuclear genome. Because this gene transfer took place over a time scale of hundreds of millions of years, direct observation and analysis of primary transfer events has remained difficult. Hence, very little is known about the evolutionary frequency of gene transfer events, the size of transferred genome fragments, the molecular mechanisms of the transfer process, or the environmental conditions favoring its occurrence. We describe here a genetic system based on transgenic chloroplasts carrying a nuclear selectable marker gene that allows the efficient selection of plants with a nuclear genome that carries pieces transferred from the chloroplast genome. We can select such gene transfer events from a surprisingly small population of plant cells, indicating that the escape of genetic material from the chloroplast to the nuclear genome occurs much more frequently than generally believed and thus may contribute significantly to intraspecific and intraorganismic genetic variation.T he evolutionary origin of eukaryotic cells is characterized by the endosymbiotic uptake of bacteria and their gradual conversion into the DNA-containing cell organelles, mitochondria, and plastids (chloroplasts) (1-3). Genetically, the evolutionary optimization of endosymbiosis was accompanied by the loss of dispensable and redundant genetic information and the large-scale translocation of genetic information from the endosymbiont to the host genome (4-6). Consequently, contemporary organellar genomes are greatly reduced and contain only a small proportion of the genes that their free-living ancestors had possessed. By using molecular methods, the origins of organelles have been traced back to specific taxa of eubacteria: Whereas cyanobacteria were identified as presumptive ancestors of plastids, ␣-proteobacteria are related most closely to mitochondria (1).Interspecific variation in the gene content of organellar genomes (7-11) suggests that gene transfer from organelles to the nucleus is an ongoing process. Moreover, pieces of chloroplast and mitochondrial DNA are often found in nuclear genomes (12-18) and commonly referred to as promiscuous DNA. These sequences lack any apparent function but may provide the raw material for converting organellar genes into functional nuclear genes, the products of which are reimported into the organelle, then allowing for subsequent loss of the genes from the organellar genome (10). In addition, promiscuous DNA of mitochondrial origin has been implicated recently in DNA repair in yeast by patching broken chromosomes (19,20).In the present study we developed an experimental system suitable for selecting and analyzing DNA transfer events from the chloroplast genome to the nuclear genome. We find that DNA escape out of the chloroplast and integration into the nuclear genome occurs much more frequently than generally believed and thus provides a mechan...

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“…One group, represented by the classic maize transposable elements, have terminal inverted repeats, duplicate host sequences upon integration, and transpose via DNA (Engels, 1983;Fedoroff, 1989). These elements usually leave characteristic footprints after excision (Doring and Starlinger, 1986;Nevers et al, 1986;Jin and Bennetzen, 1989;Singer et al, 1993;Giroux et al, 1996;Kunze et al, 1997). The second group, the retroelements, move through an RNA copy, are related to retroviruses, and include longterminal repeat and non-long-terminal repeat retrotransposons (Wessler et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

The Maize Genome Contains a Helitron Insertion

et al. 2003

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The maize mutation sh2-7527 was isolated in a conventional maize breeding program in the 1970s. Although the mutant contains foreign sequences within the gene, the mutation is not attributable to an interchromosomal exchange or to a chromosomal inversion. Hence, the mutation was caused by an insertion. Sequences at the two Sh2 borders have not been scrambled or mutated, suggesting that the insertion is not caused by a catastrophic reshuffling of the maize genome. The insertion is large, at least 12 kb, and is highly repetitive in maize. As judged by hybridization, sorghum contains only one or a few copies of the element, whereas no hybridization was seen to the Arabidopsis genome. The insertion acts from a distance to alter the splicing of the sh2 pre-mRNA. Three distinct intron-bearing maize genes were found in the insertion. Of most significance, the insertion bears striking similarity to the recently described DNA helicase-bearing transposable elements termed Helitrons . Like Helitrons , the inserted sequence of sh2-7527 is large, lacks terminal repeats, does not duplicate host sequences, and was inserted between a host dinucleotide AT. Like Helitrons , the maize element contains 5 TC and 3 CTRR termini as well as two short palindromic sequences near the 3 terminus that potentially can form a 20-bp hairpin. Although the maize element lacks sequence information for a DNA helicase, it does contain four exons with similarity to a plant DEAD box RNA helicase. A second Helitron insertion was found in the maize genomic database. These data strongly suggest an active Helitron in the present-day maize genome.

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Plant Transposable Elements

Cited by 128 publications

References 0 publications

Molecular Analysis of the anthocyanin2 Gene of Petunia and Its Role in the Evolution of Flower Color

Molecular Analysis of the anthocyanin2 Gene of Petunia and Its Role in the Evolution of Flower Color

High-frequency gene transfer from the chloroplast genome to the nucleus

The Maize Genome Contains a Helitron Insertion

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