Methylation of miRNA genes in the response to temperature stress in Populus simonii.

Dong Ci,Yuepeng Song,Deqiang Zhang,Min Tian

doi:10.3389/fpls.2015.00921

Abstract

DNA methylation and miRNAs provide crucial regulation of the transcriptional and post-transcriptional responses to abiotic stress. In this study, we used methylation-sensitive amplification polymorphisms to identify 1066 sites that were differentially methylated in response to temperature stress in Populus simonii. Among these loci, BLAST searches of miRBase identified seven miRNA genes. Expression analysis by quantitative real-time PCR suggested that the methylation pattern of these miRNA genes probably influences their expression. Annotation of these miRNA genes in the sequenced genome of Populus trichocarpa found three target genes (Potri.007G090400, Potri.014G042200, and Potri.010G176000) for the miRNAs produced from five genes (Ptc-MIR396e and g, Ptc-MIR156i and j, and Ptc-MIR390c) respectively. The products of these target genes function in lipid metabolism to deplete lipid peroxide. We also constructed a network based on the interactions between DNA methylation and miRNAs, miRNAs and target genes, and the products of target genes and the metabolic factors that they affect, including H2O2, malondialdehyde, catalase (CAT), and superoxide dismutase. Our results suggested that DNA methylation probably regulates the expression of miRNA genes, thus affecting expression of their target genes, likely through the gene-silencing function of miRNAs, to maintain cell survival under abiotic stress conditions.

Highlights

Temperature has major effects on plant growth and development in the field, where temperatures can change frequently, potentially causing stress on the plant
To evaluate the dynamic biological and physiological reactions that occur during temperature treatment, we treated 30-cm cuttings from 1-year-old branches at 42 or 4◦C for 0, 3, 6, 12, and 24 h and measured four parameters of the cuttings: H2O2 contents, and activities of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA; Figure 1)
In both heat and cold stress treatments, the activity of CAT and SOD reached a peak at 6 h; CAT and SOD activities were significantly higher under heat stress than cold at 6 h

Summary

Introduction

Temperature has major effects on plant growth and development in the field, where temperatures can change frequently, potentially causing stress on the plant. Heat or cold stress can negatively affect many physiological processes; plants have evolved complex signaling pathways that perceive and transduce signals in response to particular stresses (You et al, 2014) These signals act through H2O2, malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), which affect the degree of response to abiotic stress (Nie et al, 2015; Zhang et al, 2015). Some of these signals require transcription and are broadly regulated by a variety of factors, including cytosine methylation, covalent modification of DNA by 5-methylcytosines. The altered methylation state of CycD3-1 and Nt-EXPA5 shifted their expression during heat stress in tobacco (Centomani et al, 2015)

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