Abstract
The seed is the propagule of higher plants and allows its dissemination and the survival of the species. Seed dormancy prevents premature germination under favourable conditions. Dormant seeds are only able to germinate in a narrow range of conditions. During after-ripening (AR), a mechanism of dormancy release, seeds gradually lose dormancy through a period of dry storage. This review is mainly focused on how chemical modifications of mRNA and genomic DNA, such as oxidation and methylation, affect gene expression during late stages of seed development, especially during dormancy. The oxidation of specific nucleotides produced by reactive oxygen species (ROS) alters the stability of the seed stored mRNAs, being finally degraded or translated into non-functional proteins. DNA methylation is a well-known epigenetic mechanism of controlling gene expression. In Arabidopsis thaliana, while there is a global increase in CHH-context methylation through embryogenesis, global DNA methylation levels remain stable during seed dormancy, decreasing when germination occurs. The biological significance of nucleic acid oxidation and methylation upon seed development is discussed.
Highlights
The loss of seed dormancy through AR is a fact observed in a good number of seeds, the molecular mechanisms that govern the AR process are not entirely known
It is widely accepted that oxidation caused by reactive oxygen species (ROS) is the main mechanism leading the AR process
The recruitment of mRNAs by RNA binding proteins (RBPs) that protect them during the storage period has been proposed as a selective mechanism
Summary
Seeds are the first world crop, and the basic knowledge applied to enhance complex traits such are dormancy, viability, and vigour is essential for food security and crop production. The Delay Of Germination-1 (DOG1) gene, a quantitative trait locus controlling seed dormancy, is essential to stablish this process, but its specific molecular function is still unknown [11]. Other nucleic acid modifications, such as DNA and RNA methylation, have been described to be critical for A. thaliana embryogenesis and seed viability, facts that demonstrate the importance of these chemical marks in seed biology [33,34,36]. We discuss how mRNA and genomic (gDNA) oxidation and methylation control the expression levels of genes/proteins involved in seed dormancy release, with emphasis in the AR process. Reactive Oxygen Species (ROS) Promote Dormancy Release and Modify Stability of Nucleic Acids
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