Molecular Genetics of Transposable Elements in Plants

Döring, Hans-Peter; Starlinger, Peter

doi:10.1146/annurev.ge.20.120186.001135

Cited by 169 publications

(47 citation statements)

References 58 publications

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“…Transposable element excision events can be imprecise (Doring and Starlinger, 1986); however, a precise excision of Mu can also occur for the bzl::mu2 allele in vivo (A.B. Britt and V. Walbot, unpublished observation).…”

Section: Figure 1 (Continued)mentioning

confidence: 99%

Insertion of Mu1 elements in the first intron of the Adh1-S gene of maize results in novel RNA processing events.

Luehrsen

Walbot

1990

Plant Cell

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Maize transposable elements, when inserted in or near genes, alter expression by several transcriptional and posttranscriptional mechanisms. Three independent, unstable insertions of the transposable element Mutator (Mu) into the first intron of the Alcohol dehydfogenase-7 (Adhl) gene have been shown to decrease expression [Strommer et al. (1982). Nature 300,542-5441. We have developed an approach to elucidate the underlying molecular mechanisms responsible for the mutant phenotypes. Mul elements were inserted into Adhl-S intron 1 in vitro to create plasmid facsimiles of the mutant alleles. The Mul element was also inserted at nove1 positions within intron 1 to create new mutations. The Mul/intron constructions were placed between the Adhl-S promoter/exon 1 segment and a reporter gene (firefly luciferase or 8-glucuronidase), and these chimeric gene constructs were tested in transient assays in maize protoplasts. When compared with the appropriate control, the Mul insertions decreased reporter gene expression to levels approximating the alcohol dehydrogenase enzyme activities observed for the Adhl-S mutants in vivo. The Mul insertions also showed a polarity effect with luciferase expression increasing as the insertions were placed nearer the 3' splice junction. In addition, Mul insertions within a different intron, actin intron 3, also significantly reduced luciferase expression, indicating that Mul insertions within introns are likely to diminish expression in many genes. The presence of the Mul sequences was correlated with decreased levels of steadystate luciferase transcript. Deletion analysis of the Mul element and RNase mapping indicate that the transposable element contains RNA processing signals in its central region that are largely responsible for the decrease in expression.

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Section: Figure 1 (Continued)mentioning

confidence: 99%

Insertion of Mu1 elements in the first intron of the Adh1-S gene of maize results in novel RNA processing events.

Luehrsen

Walbot

1990

Plant Cell

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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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“…Thus, the Txl elements present a paradox by exhibiting features of two classes of mobile DNAs that are thought to have very different modes of transposition. Two possible resolutions are considered: (i) the composite versions are actually made up of two independent elements, one of the retrotransposon class, which has a high degree of specificity for insertion into a target within the other, P-like element; and (ii) the composite elements are intact, autonomous mobile DNAs, in which the pol-like gene product collaborates with the terminal inverted repeats to cause transposition of the entire unit.Once investigators accepted the concept of mobile DNA segments within otherwise stable genomes (37), the catalog of such transposable elements began to grow steadily (13,19,23,29,31,47). No phylogenetic group has been shown to be free of them, and they are presumed to be ubiquitous.…”

mentioning

confidence: 99%

“…Once investigators accepted the concept of mobile DNA segments within otherwise stable genomes (37), the catalog of such transposable elements began to grow steadily (13,19,23,29,31,47). No phylogenetic group has been shown to be free of them, and they are presumed to be ubiquitous.…”

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Composite transposable elements in the Xenopus laevis genome.

1989

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Members of two related families of transposable elements, Txl and Tx2, were isolated from the genome of Xenopus laevis and characterized. In both families, two versions of the elements were found. The smaller version in each family (Txld and Tx2d) consisted largely of two types of 400-base-pair tandem internal repeats. These elements had discrete ends and short inverted terminal repeats characteristic of mobile DNAs that are presumed to move via DNA intermediates, e.g., Drosophila P and maize Ac elements. The longer versions (Txlc and Tx2c) differed from Txld and Tx2d by the presence of a 6.9-kilobase-pair internal segment that included two long open reading frames (ORFs). ORF1 had one cysteine-plus-histidine-rich sequence of the type found in retroviral gag proteins. ORF2 showed more substantial homology to retroviral pol genes and particularly to the analogs ofpol found in a subclass of mobile DNAs that are supposed retrotransposons, such as mammalian long interspersed repetitive sequences, Drosophila I factors, silkworm Rl elements, and trypanosome Ingi elements. Thus, the Txl elements present a paradox by exhibiting features of two classes of mobile DNAs that are thought to have very different modes of transposition. Two possible resolutions are considered: (i) the composite versions are actually made up of two independent elements, one of the retrotransposon class, which has a high degree of specificity for insertion into a target within the other, P-like element; and (ii) the composite elements are intact, autonomous mobile DNAs, in which the pol-like gene product collaborates with the terminal inverted repeats to cause transposition of the entire unit.Once investigators accepted the concept of mobile DNA segments within otherwise stable genomes (37), the catalog of such transposable elements began to grow steadily (13,19,23,29,31,47). No phylogenetic group has been shown to be free of them, and they are presumed to be ubiquitous. (direct)

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Molecular Genetics of Transposable Elements in Plants

Cited by 169 publications

References 58 publications

Insertion of Mu1 elements in the first intron of the Adh1-S gene of maize results in novel RNA processing events.

Insertion of Mu1 elements in the first intron of the Adh1-S gene of maize results in novel RNA processing events.

The Maize Genome Contains a Helitron Insertion

Composite transposable elements in the Xenopus laevis genome.

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