Long terminal repeats (LTR) retrotransposons have a major role in determining genome size, structure and function, thanks to their ability to transpose. We performed a meta-analysis of LTR-retrotransposon expression in roots of sunflower plantlets treated with different plant hormones, chemicals and NaCl. By using Illumina cDNA libraries, available from public repositories, we measured the number of reads matching the retrotranscriptase domains isolated from a whole genome library of retrotransposons. LTR-retrotransposons resulted in general barely expressed, except for 4 elements, all belonging to the AleII lineage, which showed high transcription levels in roots of both control and treated plants. The expression of retrotransposons in treated plants was slightly higher than in the control. Transcribed elements belonged to specific chromosomal loci and were not abundant in the genome. A few elements resulted differentially expressed depending on the treatment. Results suggest that, although most retrotransposons are not expressed, the transcription of such elements is related to their abundance, to their position in the chromosome and to their lineage.

中文翻译：

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向日葵根 (Helianthus annuus L.) 长末端重复反转录转座子表达的计算全基因组分析

长末端重复序列 (LTR) 逆转录转座子具有转座能力，因此在决定基因组大小、结构和功能方面发挥着重要作用。我们对用不同植物激素、化学品和 NaCl 处理的向日葵幼苗根中的 LTR-逆转录转座子表达进行了荟萃分析。通过使用可从公共存储库获得的 Illumina cDNA 文库，我们测量了与从逆转录转座子的全基因组文库中分离的逆转录酶域匹配的读数数量。LTR-逆转录转座子导致一般几乎不表达，除了 4 个元件外，均属于 AleII 谱系，在对照和处理植物的根中均显示出高转录水平。处理植物中逆转录转座子的表达略高于对照。转录的元素属于特定的染色体位点，在基因组中并不丰富。一些元素根据处理结果差异表达。结果表明，虽然大多数反转录转座子不表达，但这些元件的转录与其丰度、它们在染色体中的位置和它们的谱系有关。