Intragenic methylation repatterning is associated with alternative splicing and unique epigenetic phenotypes

Area of Science:

• Plant Epigenetics and Molecular Biology
• Gene Regulation and Alternative Splicing
• Stress Response and Heritable Memory

Background:

• The role of intragenic cytosine methylation in phenotype determination remains debated.
• Previous research suggests a link between stress, alternative splicing, and epigenetic modifications, but lacks detailed analysis.
• The Arabidopsis *msh1* system provides a model for studying reproducible epigenetic states and stress-responsive phenotypes with transgenerational inheritance.

Purpose of the Study:

• To investigate the functional relationship between differential DNA methylation and alternative splicing in response to environmental stress.
• To elucidate the role of intragenic methylation in mediating stress-induced phenotypic changes and heritable memory.
• To map methylomes at single-cytosine resolution and correlate methylation patterns with transcript isoform expression.

Main Methods:

• Utilized the *msh1* mutant in Arabidopsis as an experimental system.
• Performed single-cytosine resolution methylome mapping using signal-detection and machine learning verification.
• Overlapped differentially methylated genes with *msh1*-derived transcript isoforms to analyze methylation-splicing-phenotype links.

Main Results:

• Demonstrated that specific patterns of exonic DNA methylation directly influence the expression levels of different transcript isoforms.
• Identified an enrichment of alternatively spliced and differentially methylated genes within key regulators of plant growth, development, and spliceosome components.
• Found that differentially methylated genes frequently contained a known CTT motif, suggesting a specific recognition site for methylation machinery.

Conclusions:

• Established a direct link between environmentally responsive differential methylation and alternative splicing in plants.
• Showcased how these epigenetic and post-transcriptional regulatory mechanisms contribute to stress-induced phenotypic changes.
• Highlighted the significance of intragenic methylation in mediating adaptive responses and heritable stress memory in plants.