The mobility of the tobacco Tnt1 retrotransposon correlates with its transcriptional activation by fungal factors

Melayah, D Bonnivard, E Chalhoub, B Audeon, C Grandbastien, MA

D. Melayah et al., The mobility of the tobacco Tnt1 retrotransposon correlates with its transcriptional activation by fungal factors, PLANT J, 28(2), 2001, pp. 159-168

51

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT JOURNAL

0960-7412 → ACNP

28

2

2001

159 - 168

ISI

0960-7412(200110)28:2<159:TMOTTT>2.0.ZU;2-3

We have analyzed the stress-induced amplification of the tobacco Tnt1 eleme nt, one of the rare active plant retrotransposons. Tnt1 mobility was monito red using the retrotransposon-anchored SSAP strategy that allows the screen ing of multiple insertion sites of high copy number elements. We have scree ned for Tnt1 insertion polymorphisms in plants regenerated from mesophyll l eaf cells, either via explant culture or via protoplast isolation. The seco nd procedure includes an overnight exposure to fungal extracts known to ind uce high levels of Tnt1 transcription. Newly transposed Tnt1 copies were de tected in nearly 25% of the plants regenerated via protoplast isolation, an d in less than 3% of the plants derived from explant culture. These results show that Tnt1 transcription is followed by transposition, and that fungal extracts efficiently activate Tnt1 mobility. Transcription appears to be t he key step to controlling Tnt1 amplification, as newly transposed Tnt1 cop ies show high sequence similarities to the subpopulations of transcribed Tn t1 elements. Our results provide direct evidence that factors of microbial origin are able to induce retrotransposon amplification in plants, and stre ngthen the hypothesis that stress modulation of transposable elements might play a role in generating host genetic plasticity in response to environme ntal stresses.