Dataset Information

Root-Specific Expression of a Jacalin Lectin Family Protein Gene Requires a Transposable Element Sequence in the Promoter.

ABSTRACT: Transposable elements (TEs) are widespread in the plant genome and can impact on the expression of neighbouring genes. Our previous studies have identified a number of DNA demethylase-regulated defence-related genes that contain TE sequences in the promoter and show tissue-specific expression in Arabidopsis. In this study we investigated the role of the promoter TE insertions in the root-specific expression of a DNA demethylase-regulated gene, AT5G38550, encoding a Jacalin lectin family protein. Using a promoter:GUS fusion reporter gene approach, we first demonstrated that the full-length promoter fragment, carrying four TE sequences, contained the essential regulatory information required for root-specific expression and DNA demethylase regulation in Arabidopsis. By successive deletion of the four TE sequences, we showed that one of the four TE insertions, a 201-bp TE fragment of the hAT DNA transposon family, was required for root-specific expression: Deletion of this TE, but not the first two TE sequences, converted the root-specific expression pattern to a constitutive expression pattern in Arabidopsis plants. Our study provides an example indicating an important role of TE insertions in tissue-specific expression of plant defence-related genes.

SUBMITTER: Wu Q

PROVIDER: S-EPMC6266147 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Root-Specific Expression of a Jacalin Lectin Family Protein Gene Requires a Transposable Element Sequence in the Promoter.

Wu Qiong Q Smith Neil A NA Zhang Daai D Zhou Changyong C Wang Ming-Bo MB

Genes 20181113 11

Transposable elements (TEs) are widespread in the plant genome and can impact on the expression of neighbouring genes. Our previous studies have identified a number of DNA demethylase-regulated defence-related genes that contain TE sequences in the promoter and show tissue-specific expression in Arabidopsis. In this study we investigated the role of the promoter TE insertions in the root-specific expression of a DNA demethylase-regulated gene, <i>AT5G38550</i>, encoding a Jacalin lectin family p ...[more]

PMID: 30428604

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Project description:BackgroundFluorescence in situ hybridization (FISH) is an efficient cytogenetic technology to study chromosome structure. Transposable element (TE) is an important component in eukaryotic genomes and can provide insights in the structure and evolution of eukaryotic genomes.ResultsA FISH probe derived from bacterial artificial chromosome (BAC) clone 299N22 generated striking signals on all 26 chromosomes of the cotton diploid A genome (AA, 2x=26) but very few on the diploid D genome (DD, 2x=26). All 26 chromosomes of the A sub genome (At) of tetraploid cotton (AADD, 2n=4x=52) also gave positive signals with this FISH probe, whereas very few signals were observed on the D sub genome (Dt). Sequencing and annotation of BAC clone 299N22, revealed a novel Ty3/gypsy transposon family, which was named as 'CICR'. This family is a significant contributor to size expansion in the A (sub) genome but not in the D (sub) genome. Further FISH analysis with the LTR of CICR as a probe revealed that CICR is lineage-specific, since massive repeats were found in A and B genomic groups, but not in C-G genomic groups within the Gossypium genus. Molecular evolutionary analysis of CICR suggested that tetraploid cottons evolved after silence of the transposon family 1-1.5 million years ago (Mya). Furthermore, A genomes are more homologous with B genomes, and the C, E, F, and G genomes likely diverged from a common ancestor prior to 3.5-4 Mya, the time when CICR appeared. The genomic variation caused by the insertion of CICR in the A (sub) genome may have played an important role in the speciation of organisms with A genomes.ConclusionsThe CICR family is highly repetitive in A and B genomes of Gossypium, but not amplified in the C-G genomes. The differential amount of CICR family in At and Dt will aid in partitioning sub genome sequences for chromosome assemblies during tetraploid genome sequencing and will act as a method for assessing the accuracy of tetraploid genomes by looking at the proportion of CICR elements in resulting pseudochromosome sequences. The timeline of the expansion of CICR family provides a new reference for cotton evolutionary analysis, while the impact on gene function caused by the insertion of CICR elements will be a target for further analysis of investigating phenotypic differences between A genome and D genome species.

Project description:UNLABELLED: BACKGROUND:Transposable elements (TEs) encode sequences necessary for their own transposition, including signals required for the termination of transcription. TE sequences within the introns of human genes show an antisense orientation bias, which has been proposed to reflect selection against TE sequences in the sense orientation owing to their ability to terminate the transcription of host gene transcripts. While there is evidence in support of this model for some elements, the extent to which TE sequences actually terminate transcription of human gene across the genome remains an open question. RESULTS:Using high-throughput sequencing data, we have characterized over 9,000 distinct TE-derived sequences that provide transcription termination sites for 5,747 human genes across eight different cell types. Rarefaction curve analysis suggests that there may be twice as many TE-derived termination sites (TE-TTS) genome-wide among all human cell types. The local chromatin environment for these TE-TTS is similar to that seen for 3' UTR canonical TTS and distinct from the chromatin environment of other intragenic TE sequences. However, those TE-TTS located within the introns of human genes were found to be far more cell type-specific than the canonical TTS. TE-TTS were much more likely to be found in the sense orientation than other intragenic TE sequences of the same TE family and TE-TTS in the sense orientation terminate transcription more efficiently than those found in the antisense orientation. Alu sequences were found to provide a large number of relatively weak TTS, whereas LTR elements provided a smaller number of much stronger TTS. CONCLUSIONS:TE sequences provide numerous termination sites to human genes, and TE-derived TTS are particularly cell type-specific. Thus, TE sequences provide a powerful mechanism for the diversification of transcriptional profiles between cell types and among evolutionary lineages, since most TE-TTS are evolutionarily young. The extent of transcription termination by TEs seen here, along with the preference for sense-oriented TE insertions to provide TTS, is consistent with the observed antisense orientation bias of human TEs.

Dataset Information

Root-Specific Expression of a Jacalin Lectin Family Protein Gene Requires a Transposable Element Sequence in the Promoter.

Publications

Root-Specific Expression of a Jacalin Lectin Family Protein Gene Requires a Transposable Element Sequence in the Promoter.

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