Maize RNA polymerase IV defines trans-generational epigenetic variation

Area of Science:

• Plant Molecular Biology
• Epigenetics
• Genomics

Background:

• Maize RNA Polymerase IV (Pol IV) has an expanded role in gene regulation compared to other species.
• The characteristics and prevalence of Pol IV-regulated genetic elements (haplotypes) are largely unknown.
• Pol IV is crucial for paramutation, gene expression control, and small interfering RNA (siRNA) generation.

Purpose of the Study:

• To investigate the characteristics and prevalence of Pol IV-regulated haplotypes in maize.
• To understand how Pol IV influences the expression patterns of specific genetic loci.
• To explore the role of transposon sequences in Pol IV-mediated gene regulation.

Main Methods:

• Analysis of specific haplotypes at the purple plant1 locus in maize.
• Studying the effects of Pol IV mutations on haplotype expression patterns over generations.
• Investigating the association of transposon fragments with altered gene expression.

Main Results:

• Specific purple plant1 haplotypes acquired expanded expression domains after transmission from siRNA mutants.
• This expanded expression was enhanced over generations in Pol IV mutants and remained heritable.
• The phenomenon was linked to promoter-proximal transposon fragments but not paramutation sequences.
• Trans-generational Pol IV action defines haplotype expression patterns using transposon-derived regulatory elements.

Conclusions:

• Maize Pol IV action establishes heritable gene expression patterns through transposon co-option.
• Induced changes in the genome's heterochromatic component correlate with heritable gene regulation changes.
• This Pol IV regulatory system offers a mechanism for generating adaptive traits.