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

Area of Science:

• Plant molecular biology
• Genetics
• Microbiology

Background:

• The tobacco Tnt1 element is a rare active plant retrotransposon.
• Retrotransposon activity can be influenced by environmental stresses.

Purpose of the Study:

• To analyze stress-induced amplification of the tobacco Tnt1 element.
• To investigate the role of microbial factors in Tnt1 mobility.

Main Methods:

• Monitoring Tnt1 mobility using the retrotransposon-anchored SSAP strategy.
• Screening for Tnt1 insertion polymorphisms in regenerated tobacco plants (explant culture vs. protoplast isolation).
• Exposing plants to fungal extracts to induce Tnt1 transcription.

Main Results:

• Newly transposed Tnt1 copies were detected in ~25% of plants regenerated via protoplast isolation (with fungal extracts).
• Less than 3% of plants derived from explant culture showed new Tnt1 copies.
• Fungal extracts efficiently activated Tnt1 mobility, with transcription preceding transposition.

Conclusions:

• Microbial factors can induce retrotransposon amplification in plants.
• Stress modulation of transposable elements may generate host genetic plasticity in response to environmental stresses.
• Transcription is a key regulatory step controlling Tnt1 amplification.