Temporal changes in transcripts of miniature inverted-repeat transposable elements during rice endosperm development

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• DNA methylation represses transposable element (TE) transcription to maintain genome integrity.
• TEs can escape host defenses and reactivate transcription.
• DNA demethylases target TE sequences in rice and Arabidopsis female gametophytes, with genome-wide demethylation occurring in the endosperm post-fertilization.

Purpose of the Study:

• To survey transcripts generated from TEs during rice endosperm development.
• To compare TE transcript expression in the endosperm with the embryo.
• To identify regulatory mechanisms controlling TE activity in the endosperm.

Main Methods:

• Custom microarray analysis of TE transcripts during rice endosperm development.
• Comparative analysis of TE expression in embryo tissues.
• Bioinformatic analysis to identify transcription factor binding motifs near TEs.

Main Results:

• TE transcript expression exhibits dynamic up- and downregulation throughout rice endosperm development.
• Miniature inverted-repeat TEs (MITEs) show particularly dynamic expression patterns.
• Some TE transcripts are directionally controlled, unlike other DNA transposons and retrotransposons.
• The NUCLEAR FACTOR Y binding motif (CCAAT) was identified near the 5' terminal inverted repeat of a transcribed MITE (Youren).

Conclusions:

• Transposable element activity is highly dynamic during rice endosperm development.
• Specific TEs, particularly MITEs, are subject to complex transcriptional regulation.
• The discovery of the NF-Y binding motif suggests potential regulatory pathways for TE control in the endosperm.