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Updated: Jun 11, 2026
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Agrobacterium-Mediated Immature Embryo Transformation of Recalcitrant Maize Inbred Lines Using Morphogenic Genes
Published on: February 14, 2020
RNA-mediated trans-communication can establish paramutation at the b1 locus in maize.
Mario Arteaga-Vazquez1, Lyudmila Sidorenko, Fernando A Rabanal
1BIO5 Institute and Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA.
Summary
Paramutation, an epigenetic process in maize, involves RNA-mediated gene silencing. The mediator of paramutation (mop1) gene and b1TR-derived siRNAs are crucial for this heritable change in gene expression.
Area of Science:
- Epigenetics
- Plant Molecular Biology
- RNA Biology
Background:
- Paramutation is an epigenetic phenomenon causing heritable changes in gene expression between alleles.
- It requires specific noncoding tandem repeat (b1TR) sequences and implicates RNA-mediated mechanisms.
- The mediator of paramutation (mop1) gene, encoding an RNA-dependent RNA polymerase-like protein, is essential for paramutation.
Purpose of the Study:
- To investigate the function of the mop1 gene in paramutation.
- To explore the role of small interfering RNAs (siRNAs) derived from b1TR sequences in paramutation.
- To understand the mechanism of RNA-mediated epigenetic information transfer between alleles.
Main Methods:
- Analysis of siRNA production from b1TR sequences in relation to mop1 function.
- Nuclear transcription assays to determine the transcription of b1TR sequences.
- Examination of siRNA production in non-paramutating alleles.
- Recapitulation of b1 paramutation using transgenes expressing hairpin RNA to produce b1TR-siRNAs.
Main Results:
- siRNA production from b1TR sequences is dependent on a functional mop1 gene, but repeat transcription is not.
- b1TR-siRNAs are produced even in alleles incapable of paramutation, indicating they are not sufficient alone.
- Paramutation can be induced by expressing b1TR-siRNAs from a transgene, suggesting their involvement.
- mop1 also plays a role in the biogenesis of a subset of microRNAs (miRNAs).
Conclusions:
- The study suggests that b1TR-siRNAs or their dsRNA template mediate the inter-allelic communication establishing paramutation.
- mop1 is essential for b1TR-siRNA production and also functions in miRNA biogenesis.
- RNA-mediated mechanisms, involving siRNAs and potentially dsRNA, are central to paramutation in maize.
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