Transposable elements (TEs) occupy a substantial portion of the genome of most plant species, differing in sequences and abundance. These sequences, which are able to change their chromosomal location within the host genome, are now known to have a major role in fostering genome evolution, introducing genetic variability and shaping genome structure. As matter of fact, TEs are able to cause genetic mutations through their amplification/loss mechanisms being also one of major drivers in genome size variations. Furthermore, they play a role in the epigenetic settings of the genome, regulating chromatin organization in the nucleus, and acting as control elements for the expression of closer genes. Over the last decade, it has become clear that environmental stimuli, along with some stress conditions, can trigger the activity of certain TE families and lead to new TE insertions in the host genome. New TE insertions may cause flanking genes to become transcriptionally responsive to the same stress conditions that firstly activated the TE. This kind of fine-tuning of gene activity can rise to altered gene expression patterns and phenotypes that may help the host plant to adapt more rapidly to new environmental conditions. Stress-induced TE transcription and, in some cases, transposition have been noticed for different classes of TEs and under different stress conditions. However, the most responsive elements seem to be the ones belonging to some long terminal repeat (LTR) families. Here we present a meta-analysis of LTR-retrotransposon expression in response to different environmental conditions in two model species: an herbaceous species, Helianthus annuus, and a woody plant, Populus trichocarpa. By using available expression data resources we were able to analyze the expression of retrotransposons in plants treated with different compounds mimicking stress or directly subjected to stresses (drought, cold, heat, and salt), as well as in control plants. Overall, our analyses showed that the expression of retrotransposons was generally low in both normal and stressful culture conditions: a few elements resulted differentially expressed depending on the treatment. Overall results suggest that the transcription of such elements is related to their abundance, to their position in the chromosome and to their lineage rather than to specific stresses. However, a few elements were specifically activated by some stresses. Since LTR-RE expression is just the first stage of retrotransposition, further analyses are necessary to estimate subsequent stages of retrotransposition, including the possible insertion of new elements in the genome, in order to elucidate the biological significance of retrotransposon activity in response to environmental stimuli.
Do environmental changes induce retrotransposon expression in plants?
F. Mascagni;A. Vangelisti;G. Usai;T. Giordani;L. Natali;A. Cavallini.
2019-01-01
Abstract
Transposable elements (TEs) occupy a substantial portion of the genome of most plant species, differing in sequences and abundance. These sequences, which are able to change their chromosomal location within the host genome, are now known to have a major role in fostering genome evolution, introducing genetic variability and shaping genome structure. As matter of fact, TEs are able to cause genetic mutations through their amplification/loss mechanisms being also one of major drivers in genome size variations. Furthermore, they play a role in the epigenetic settings of the genome, regulating chromatin organization in the nucleus, and acting as control elements for the expression of closer genes. Over the last decade, it has become clear that environmental stimuli, along with some stress conditions, can trigger the activity of certain TE families and lead to new TE insertions in the host genome. New TE insertions may cause flanking genes to become transcriptionally responsive to the same stress conditions that firstly activated the TE. This kind of fine-tuning of gene activity can rise to altered gene expression patterns and phenotypes that may help the host plant to adapt more rapidly to new environmental conditions. Stress-induced TE transcription and, in some cases, transposition have been noticed for different classes of TEs and under different stress conditions. However, the most responsive elements seem to be the ones belonging to some long terminal repeat (LTR) families. Here we present a meta-analysis of LTR-retrotransposon expression in response to different environmental conditions in two model species: an herbaceous species, Helianthus annuus, and a woody plant, Populus trichocarpa. By using available expression data resources we were able to analyze the expression of retrotransposons in plants treated with different compounds mimicking stress or directly subjected to stresses (drought, cold, heat, and salt), as well as in control plants. Overall, our analyses showed that the expression of retrotransposons was generally low in both normal and stressful culture conditions: a few elements resulted differentially expressed depending on the treatment. Overall results suggest that the transcription of such elements is related to their abundance, to their position in the chromosome and to their lineage rather than to specific stresses. However, a few elements were specifically activated by some stresses. Since LTR-RE expression is just the first stage of retrotransposition, further analyses are necessary to estimate subsequent stages of retrotransposition, including the possible insertion of new elements in the genome, in order to elucidate the biological significance of retrotransposon activity in response to environmental stimuli.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
