Rice transposable elements are characterized by various methylation environments in the genome

Area of Science:

• Genomics
• Epigenetics
• Plant Biology

Background:

• Transposable elements (TEs) are extensively targeted by DNA methylation, but their genomic methylation context remains poorly understood.
• The rice genome harbors diverse TE families with varied genomic distributions and characteristics.
• Investigating DNA methylation around TEs in rice and its wild relatives is crucial for understanding genome regulation.

Purpose of the Study:

• To investigate the DNA methylation states surrounding 12 transposable element families in cultivated and wild rice strains.
• To determine if specific methylation patterns are associated with different TE families and their genomic locations.
• To explore the relationship between TE characteristics (e.g., class, distribution) and their methylation environments.

Main Methods:

• Utilized transposon display (TD) to analyze DNA methylation patterns in nine rice genomic DNA samples.
• Examined 12 distinct transposable element families, including class I and class II elements.
• Assessed methylation degrees in sequences flanking TEs across different rice strains.

Main Results:

• Transposable element families exhibited differential chromosomal distributions, from centromeric to euchromatic regions.
• TEs were embedded in flanking sequences with varying methylation degrees, consistent across rice strains for each TE.
• Class I elements were generally in highly methylated regions, while class II elements showed diverse methylation levels.
• Some TE families displayed methylation degrees lower than the genomic average, with distance-dependent methylation changes observed in two families.

Conclusions:

• Rice transposable element families are characterized by distinct surrounding DNA methylation states.
• TE copy number and conservation are unlikely to correlate with the degree of DNA methylation.
• This study establishes a link between transposable elements and specific, characteristic methylation environments within the genome.